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Neo=new and plasma =thing formed

• It is new growth of cells, which proliferate continuously without control and have no orderly structural arrangement, but resembling in various degrees the normal cells from which it arises and served no useful function and have no clear understood cause. • It is an abnormal mass of tissue which exceed and uncoordinated with that of the surrounding tissue and persist in the same manner after cessation of the stimuli.

Pthologic pourposless • uncontrolled,unfunctional ,unusfull overgrowth PPUUUO •

It occurs when

Group of cells becomes free of normal growth control mechanisms (totally ignoring the regulatory influence of the body that control normal cell growth),

Grows without regard for the normal structural and functional aspects of a tissue or an organ and becomes a rebellious autonomous state.

• Every neoplasm is a tumor, because neoplasms usually form a swelling (tumor) • Not every tumor is a neoplasm as; it may be an abscess, hematoma, parasitic nodule or edema. • Neoplasm and tumors refer to benign or malignant growth, • Cancer is commonly used to refer to malignant neoplasms without reference to specific type. • Cancer came from the Latin word which mean crab.

Tumor etiology

• Cancer is a genetic disorder that arises from a single body cell (monoclonal disorder). • In humans and other animals, it may be triggered by noxious chemical, viral, and physical agents with mutagenic effects The causes of neoplasia are numerous, but all must have the ability to induce mutation in those portions of cell's genome that control mitotic division and differentiation.

Genetic alteration Germ line sequences present

somatic changes that accumulate in individual cells and tissue of the body over time.

Carcinogens are substances that are known to cause cancer or at least produce an increased incidence of cancer in animal and human.

We have to know Most causes of neoplasms is unknown Cells Cells



Most cases of cancer are probably multi-factorial Signals from the cell surface and transmitted to nucleus to initiate division

The process of cell division is controlled by certain genes called proto-oncogenes.

• The activation and suppression of transcription of these proto-oncogenes is controlled by other genes called regulatory genes. • The products of the regulatory genes are either initiate or terminate DNA synthesis and transcription of genes involved in cell growth and differentiation (turn of or turn on the proto-oncogenes). • So the mutation responsible for neoplastic transformation may involve proto-oncogenes directly or the genes regulate their expression.

Causal tumorigenesis To induce tumor: dysfunction of the following must be occurs

• • • • • •

DNA repair Communication factors Cell death regulators Proliferation regulators Differentiation factors Immune factors

Steps of carcinogenesis Initiation • It is the first step and means induction of cell's DNA permanent mutation (irreversible) but not, transformed. • The altered cells and its progeny are susceptible to transforming events by the same chemical or other promoters. • It needs at least a single round of DNA replication for fixation of genetic changes.

Promotion The second stage of tumor development which means outgrowth of initiated cells in response to selective stimuli (promoters) They are a chemical substance that transformed the initiated cells It produce its effect through interfering with normal signal transduction pathway that control cell proliferation and differentiation. •Some chemicals can act as initiator and promoter in the oncogenesis of some neoplasms.

progression • It means conversion of benign tumors to malignant one. Preneoplastic

Initiated cells

Benign tumor



Genetic irreversible

Non genetic reversible

Progression Genetic/non genetic

Malignant tumor

Normal cell

Spontaneous genetic mutation (Intrinsic. 1 (factors • The DNA replication is a relatively error-free phenomenon. But when the cell shows spontaneous mutation, a repair mechanism eliminates the mutation through proofreading and repair mechanism. • Moreover, some cells contain mutation not be compatible with survival and die. • In some rare cases the cell containing mutation escape the DNA recognition and repair, immune surveillance, and continue to divide giving clones of neoplastic cells containing the mutation.

• Spontaneous genetic mutation that results in neoplastic transformation may involve one or more proto-oncogenes directly or the genes regulate their expression (c-oncogene)

•DNA damaging agents are produced as byproduct of ordinary metabolism such as reactive oxygen species.

Hereditary. 2 • Hereditary plays an important role in the incidence of some neoplasms as squamous cell carcinoma of the eye in Hereford cattle • It is clear that the incidence of neoplasms increases with increasing age • The neoplasms appear to be more frequently n males

Metabolic and deficiency. 3 The incidence of neoplasms affected by •Habit of eating, drinking or with deficiency of some ingredients Such as •The thyroid neoplasms are associated with the goiter of iodine deficiency and common in Switzerland. •Alcohol drinking increases the risk of hepatic tumors. About 90% of primary liver neoplasms in man are based on previous cirrhosis. .

Radiation carcinogens. 4 all forms of radiation are complete carcinogens (they are able both .)to initiate and with continued exposure to promote tumorigenesis A-Ultraviolet radiation (UV) from sunlight

• Associated with skin cancer • The UV induced neoplasms through multifactorial involving DNA damage and failure to recognize and repair the damage results in further transcription and finally in neoplasia.

• Suppression of cell mediate immunity is also thought to the progression of the neoplastic transformed cells.

B-Ionizing radiation

• It may cause cell death or mutation. • The mutation either induced by the direct effect or by generation of free radicals. • The mutation may be involving direct mutations to proto-oncogenes give rise to cellular oncogenes (concogenes) or alteration in the genes that regulate the proto-oncogenes as suppressor genes. • It occurs more in growing animals than adult. In adults it occurs in tissue with high rate of mitotic activity as bone marrow than those of low mitotic one.

Chemical induced neoplasms. 5 The numbers of chemical carcinogens is continuously increasing A. Direct acting carcinogens. It acts locally at the site of application without having to undergo metabolic change in the body as alkylating agents. There are few direct acting carcinogens; these are highly reactive electrophiles (chemicals that react with negatively charged substance including DNA.

B. Indirect acting carcinogens (procarcinogens)

• This group contains most chemical carcinogens. • Those chemicals are not producing cancer directly, but need to be metabolized in liver by enzymes of cytochrome P-450 detoxifying system firstly to produce highly carcinogenic substance. • These include polycyclic hydrocarbons

Viruses induced neoplasms:-5 • Viruses as a cause of cancer were first identified in animals. • Viruses have long been known to cause cancer in animals. • Both RNA and DNA viruses are reacting with DNA to induced tumors. • RNA viruses that cause neoplasms are members of retroviridae. • Oncogenic DNA viruses include poxviridae, herpesviridae, papovaviridae, adenoviridae and hepadnaviridae (hepatitis B viruses of man).

Oncogenic viruses-induced neoplasms by

• (1) Interfering with normal regulation and expression of proto-oncogenes and antioncogenes. • (2) By inserting a viral encoded homolog of proto-oncogenes (viral oncogenes) into the host cell genome

Parasite induced neoplasia. 6 • Certain parasites are associated with induction of some neoplasms. as Schistosoma

7-Chronic inflammation It is probably acting as a co-factor leading to increased replication rate of affected tissue with increase the incidence of mutation.

Nomenclature (Naming) and classification of tumors Parenchyma transformed neoplastic cells





non neoplastic fibrovascular stroma that gives the frame work for growth and blood and nutrient for growth of neoplastic cells.

Naming of tumor Epithelial


Non epithelial






Mixed tumor



Add suffix oma

Ů?Add suffix Sarcoma

Classification of tumor • • • • • •

Histogenic Behavior. Necked eye appearance (macroscopic picture( Embryological, Histological Etiological classifications

• Teratoma is a neoplasm that contain haphazardly arranged mixture of tissue elements derived from all three germ layers (ectoderm, endoderm and mesoderm) Polyp refers to benign growth either hyperplastic or neoplastic that protruded from the surface of mucous membrane. They seen frequently in mucous membrane of upper respiratory, digestive and lower female genital tracts Hamartoma is disorganized but mature mesenchymal or epithelial tissue found in normal anatomic location. Hamartoma represent the result of aberrant differentiation rather than neoplasia and their behavior is completely benign. It stops its growth with growth of the body

Characteristics of benign and malignant neoplasms A-In vivo characters of benign and malignant tumors 1. Degree of differentiation and cytological features Differentiation means the degree to which the neoplastic cells resemble their normal counter part in both microscopic picture and function. In general malignant tumors appear less differentiated than benign tumors. The undifferentiated malignant cells called anaplastic cells.

2. Rate and manner of growth • In general benign tumors grow slowly over a period of months or years. • It is usually tend to compress the surrounding tissue leading to pressure atrophy or necrosis. • Malignant tumors vary widely in rat of growth. Some grow faster and other grows slowly. • Moreover, the rate of growth of malignant tumors correlates with stage of differentiation. • Most malignant tumors are invasive and progressively replace the surrounding tissue. The pattern of growth of malignant tumors is haphazard, random and uncontrolled.

3. Local invasion The benign tumors not have the ability to infiltrate, invade or metastasize. Some benign tumors, as leiomyoma, papilloma, hemangioma and osteoma do not have capsule. Malignant tumors are growing by infiltration, invasion, destruction and penetration of the surrounding tissue. They usually do not have well-developed capsule.

• The anaplastic cells have the ability to secrete various enzymes (collagenase, elastases, proteineases, peptidases and plasmin) involving in degrading collagen component of the basement membrane and extracellular matrix as will as various glycoproteins. • The degrading action opens a path for the neoplastic cells. • These processes involve cell receptors reacting with component of ECM and basement membrane including laminin, collagen and fibronectin.

Invasiveness process • 1-Loosening of anaplastic cells due to loss of certain integrin • 2-attachment of anaplastic cells to matrix component as laminin and fibronectin through specific receptors • 3-Local degradation of ECM through secretion of proteolytic enzymes as collagenase IV • 4-Locomotion in respond to certain cytokine secreted by anaplastic

Character of locally malignant tumors They are tumors characterized by the ability to infiltrate locally but don't have metastasis. They grow slower than malignant tumors, and they usually infiltrate locally and usually non capsulated, cytologically and histologically malignant and recur after incomplete removal. They include basal cell carcinoma and tumor of nervous system

Metastasis-4 • Metastasis refers to the spread of nest of malignant cells site away from the primary tumor and grow at the new location. Metastasis occurs by one of the three basic routes 1. Direct exfoliation of tumor cells from a primary tumor into a body cavity (transoelomic) 2. Implantation as from lower to upper lip 3. By invasion of lymphatics and transport of tumor cells as emboli 4. By invasion of blood vessels and transport as emboli.

• Carcinoma tends to be metastasis through lymph vessels and sarcoma through blood vessels. Veins are more easily penetrated than artery and the invaded neoplastic cells follow the venous flow draining the site of neoplasm, so 1-Abdominal malignant tumors drained by portal vein to the liver 2-Other tumors drained by systemic vein to the lungs Mechanisms of metastasis 1-Invasion of extracellular matrix

• 2-Vascular dissemination and homing of tumor cells The tumor cells in blood are susceptible to destruction by the host immune system if not aggregated together and to fibrin and platelets to form tumor emboli. The tumor emboli easily trapped and arrested in microvasculature At the site of arrest the cells adhere to the endothelial cells and escape through the vascular wall by secreting proteolytic enzymes similar to that occur in invading. As mentioned before tumor emboli of systemic vein arrested in lung; of portal veins in liver and of pulmonary veins in liver.

Genetic properties of tumor cell. 5 •

Most neoplasms are of monoclonal origin

The neoplastic cell evades the immune system and survives in new place to form daughter cells (initiation).

The initiated cells need a specific agent to enhance development of neoplasm from them.

During this proliferation the neoplastic cells may get further mutation confer properties of survivability in process called progression.

Progression usually used to refer to the stage where benign tumors become malignant or a low-grade cancer to high grade.

In vitro properties of tumor cells • A. Failure to undergo contact inhibition The neoplastic-cultured cells not stop growing after forming the monolayer • These phenomenon results of failure of cells to react to normal cell membrane signaling mechanisms that stops cells from dividing once they become coupled to or in contact with one another. • B. Diminished Binding ability Neoplastic cells do not bind to each other as normal cells

• C. Lack of anchorage dependence • Normal cells have to adhere to the surface before starting to divide but neoplastic cells not. • D. Failure to undergo normal differentiation • Neoplastic cells generally do not become fully differentiated • E. Immortalization • Normal cells cultured have certain number of cell division and die after that but neoplastic cells can be passage indefinitely.

General macroscopic neoplasms Size. It varies from 1mm up to several centimeters in size. Weight. It varies from few m gm up to several kilograms Shape. • . Benign neoplasms may be wart like, fungoid, villous, spinous, polypoid, and papillomatous. • Malignant neoplasms usually not take especial shape but usually infiltrated.

• Color:-The color of epithelial neoplasms usually grays in color but those of nonepithelium usually red or brown or black in color. Yellow in case of fat tumor, red in hemorrhagic tumor and black in melanoma • Consistency:-The neoplasms may be soft (degeneration and suppuration occurs) or firm (fibrous tissue) hard (bone tumor) also may be cystic.

Microscopic appearance-2 • The microscopic picture of benign neoplasms usually appear similar to its parent tissue structure. Malignant neoplasms Changes in nucleus The neoplastic cells show enlarged, vesicular and hyperchromatic nuclei with typical and atypical mitotic divisions

The cellular changes The malignant neoplasms characterized by hypercellularity, pleomorphism, tumor giant cell and undifferentiated cells

Spread of neoplasms Benign tumors Do not penetrate or invade the surrounding tissue or metastasize to distance site, but usually expansible.

Malignant tumors •Highly invasive and infiltrate the adjacent tissue •Metastasize •Some malignant tumors are non-metastasize such as those of central nervous system.

Methods of spread of malignant tumors 1. Direct extension It has localized growth as carcinoma in situ or basal cell carcinoma 2. Invasion They infiltrated or invaded the surrounding tissue.

The tumor cells must be detached from the main tumor mass through altered the intercellular adhesion structure including desmosomes and adherence junction

Penetration and invasion of the surrounding tissue occurs in three steps Binding



The tumor cells firstly bind to the extracellular matrix as laminin, proteoglycans and collagen through surface receptors such as integrin.

Degradation of the extracellular matrix through secretion of enzymes as proteineases, collaginases and cystein proteinases. The malignant cells move through secretion of autocrine motility factors.

Metastasis. 3 Metastasis refers to the spread of malignant cells from one site to another not directly connected with it through blood or lymph or both.

A. Hematogenous metastases

B. Lymphatic metastases

C. Implantation or seeding



Growth rate




Rounded with stalk

diffuse without stalk

Mode of growth

By expansion

By invasion

The progress of growth






Capsulated Not occur


Usually small

Usually large Microscopic Picture



Undifferentiated with variable degree

Stroma Hemorrhage

Well formed Little or no hemorrhage


Poorly formed Hemorrhage usually occur


Little necrosis



Few mitosis

Numerous mitosis

basement membrane



Blood vessel

Well developed

Ill developed


Less cellular

Highly cellular









Present Prognosis


Occur in case the tumor in vital organ

Death usually occurred

Biology of invasion and metastasis The malignant cells should follow the following steps to metastasize • 1. Invasion of the basement membrane underlying the tumor. • 2. Movement through the extracellular matrix. • 3. Penetration of the vascular and lymphatic channel. • 4. Survival and arrest within the blood or lymph. • 5. Exit from the circulation into a new site. • 6. Survival and grows in a new site.

Clinical effects and fat of cancer The fate of neoplasms depends upon type of, location of tumor, and the tissue of origin of neoplasm. • 1. Fever. It is common for cancer patients to have fever of unknown origin. • 2. Anorexia and weight loss. Anorexia weight loss and cachexia is very common in-patient with cancer due to the production of toxins or lead to starvation. • 3. Anemia. It is one of the most finding in-patients with cancer due to hemorrhages and toxins and starvation.

• 4. Obstruction of any lumen, as in case of stomach or intestine or nasal cavity or urinary bladder. • 5. Pressure atrophy of neoplasm on the surrounding tissues. • 6. Emaciation • 7. Over production of hormones causing abnormalities • 8. Death results from presence of neoplasm in vital organs or destruction of primary and secondary site

I-Epithelial tumors A. Covering epithelium 1. Papilloma (wart) Definition Location Animal susceptible Causes It may be viral or non-viral. Transitional cell papilloma is caused by Schistosoma hematobium. Gross appearance Microscopic appearance Prognosis

Squamous cell carcinoma. 2 Def Location Macroscopic picture The surface of rapidly growing carcinoma is usually inflamed . and ulcerated Squamous cell carcinoma appeared as variable firm elevated nodular, crusty and ulcerative with raised edges and necrotic .floor It has offensive odor because of surface necrosis and .putrefactive bacteria . The cut surface is grayish-white in color with distinct stroma .The regional lymph nodes are swollen

Microscopic picture •

The neoplastic cells are extend as masses and cords of cells into the dermis or underling tissue. Cross section of these cords shows islands of epithelium separated by fibrous stroma.

The neoplastic cells are arranged together where basal cells come to lie at the periphery and the most superficial one occupying the center. The center is often containing laminated red staining keratin.

The adjacent cells become flattened and the outer cell layer are present (prickle cell layer) this picture is similar to the Bird nest and called cell nest or epithelial pearl (Pathognomonic lesion).

The anaplastic cells show pleomorphism. The nuclei are large, vesicular, hyperchromatic and contain typical and a typical mitotic.

The underlying tissue shows signs of local inflammatory reaction.

The stroma is well distinct and prominent, bundles of connective tissue separated the malignant cells, but the blood vessels are well developed.

Keratoacanthoma (non-metastasizing. 3 )squamous cell carcinoma • It is usually small and restricted to the epidermis. • All layers of the epidermis proliferated downward. • It is a keratinaceous cyst not a true neoplasm. Animal susceptible: Keratoacanthoma is usually seen mainly in dogs and sheep. Location : Generally the dorsum of the body Macroscopic appearance It observed as a dermal or subcutaneous mass, Microscopic appearance The lesion is a multiloculated keratin cyst filled with concentrically laminated keratin surrounded by hyperplastic epithelium.

Basal cell carcinoma )(Rodent ulcer, malignant ulcer, and unhealed ulcer It is locally malignant tumor originate from the basal cell layer and characterized by locally infiltrate and never metastasis. • It is observed in skin of face, head and neck of susceptible animals. It associated with old age especially with exposure to sun light in susceptible animals. It is common in dogs and less common in cat, horse and rabbit but rare in other animals Macroscopic appearance The tumor is firm, non-metastasize and ulcerated. It grayish in color. Affected area appeared hairless and ulcerated. The ulcer has raised inverted edge and crusted floor

Microscopic appearance • Sheets of malignant cells, take any shape. • The anaplastic cells are arranged in cords of one cell layer, and their longitudinal axis appeared at right angle to the axis of the cord. • The malignant cells are small with deep hyperchromatic basophilic, rounded or oval nuclei. • The connective tissue stroma may be abundant in one part and scanty in another part. • The mitotic Figures aren’t abundant. • Prognosis: The prognosis is good.

B. Glandular epithelium 1. Adenoma It is a benign tumor arising from glandular epithelium including the endocrine glands.

Macroscopic picture It is well defined, encapsulated mass, round or oval and attached to or embedded in the gland of origin. The color is pale. It firm in consistency in the papillary adenoma, but soft in cystic adenoma.

Microscopic picture It is similar to the gland, from which they originate The amount of glandular tissue is more and the acini sometime lined by more than one layer with intact basement membrane. In endocrine gland, the adenoma may consist of sold mass or cords of cells as liver and adrenal adenomas • Sometimes, adenoma retained the secretion leading to dilation of acini and atrophy of epithelial lining as in thyroid adenoma in dog and horse so that it called cystadenoma. • In some cases, the epithelial lining forms branches and through into folds in acinar lumen, which called papillary adenoma. • Moreover, fibroadenoma means mixed tumor of fibroma and adenoma.

Adenocarcinoma • It is the malignant tumor of glandular epithelium (exocrine and endocrine). • It more frequent in old ages so it is common in horse, dog and dairy cattle. Macroscopic appearance The macroscopic picture is varied according to its location and the gland tissue of which it arise and the age of tumor. Primary adenocarcinoma in the mucosal surface may be observed as sharply defined or may be take the cauliflower appearance and ulcerating. In the internal organs it does not follow any rules. Secondary adenocarcinoma, appeared usually as well defined rounded, nodular, firm and gray, it located

Microscopic picture • The adenocarcinoma consists of highly undifferentiated malignant cells of acini or alveoli. • The infiltrating malignant cells take the form of cords or glandular ducts. • The acini may be lined with single or several layers and not limited by the basement membrane and also invaded the surrounding tissues. • The cells show signs of anaplasia. • Adenocarcinoma may be papillary or cystic or papillary cystic.

II-Non epithelial mesenchymal tumors 1. Fibroma • It is the benign tumor of fibroblasts and most common in skin and subcutis. Hard fibroma

Soft fibroma

(Fibroma durum)

)Fibroma molle(



The size and weight of fibroma is varied. The consistency soft or hard (fibroma durum(. Soft fibroma is grayish in color and has pink cut surface. Hard fibroma is grayish in color and the cut section is white or yellow

Microscopic appearance Fibroma is formed of interlacing bundles of fibroblasts and collagen fibers in variable proportions. The bundles tend to arranged around the blood vessels forming the whorl shape appearance. •

Fibroblasts are spindle in shape and have large elongated nuclei with tapered end.

• The soft fibroma is highly cellular with less collagen fibers and contains quite numerous vascular and lymphatic vessels, but hard fibroma is less cellular, less vascular but collagen fibers are abundant.

Fibrosarcoma. 2 • It is the malignant neoplasm of fibroblast. It occurs more common in adult or aged animals Macroscopic pictures It is nodular, poorly demarcated and usually nonencapsulated. The consistency is soft homogenous, and reddish in color. Hemorrhage and necrosis are seen in cut surface. The surface of superficial tumors is ulcerated.

Microscopic picture • Whorls or interlacing bundles of immature fibroblasts. • The malignant cells are pleomorphic, spindle, fusiform or polygonal in shape. Tumor giant cells may be seen in highly malignant one. • The nuclei are enlarged, vesicular, rounded or oval, hyperchromatic and showed typical and a typical mitotic figures. • The stroma is indistinct with numerous blood spaces. • Hemorrhage necrosis and secondary infection are common. • Prognosis: The prognosis is bad and metastasis occurs through blood to lungs and other organs.

Equine sarcoid. 3 It is cutaneous tumor of equine originated from fibroblasts. It is believed to be caused by virus. It is a tumor of equine particularly mule and donkey besides horse. It occurs more frequent on the skin of legs, head, neck and prepuce. Macroscopic picture The tumor characterized by overgrowth of variable in size and shape with ulcerated and infected skin. The overlying skin is thickened and later on ulcerated. Microscopic appearance It is consists of mixed fibroma, fibrosarcoma like cells which covered with hyperplastic epithelium of epidermis or ulcerated with infiltration the underlying by inflammatory cells mainly neutrophils.

Myxoma. 4 • It is a rare tumor of white connective tissue which capable to produce mucin. Macroscopic pictures The myxoma is soft and non-encapsulated. It is vary in shape and size but they are usually not large. Their cur surface is moist, glistening and slimy due to mucin content. Microscopic pictures Myxoma consists of spindle shaped and stellate fibroblast cells with same shape nuclei. The cells have branching fibrils process, which are suspended in an abundance of intercellular mucin, which stain blue with hematoxylin and eosin.

Myxosarcoma- 5 • It is a malignant tumor originated from white fibrous tissue. It is rare in animals • Macroscopic picture • It is the same as myxoma in addition to infiltration of surrounding tissue. • Microscopic picture • It is the same as myxoma in addition to numerous mitotic figures.

B. Neoplasms of adipose tissue 1. Lipoma • Lipoma is a common benign tumor of adipose tissue in adult and aged animals particularly female. It occurs in places where fat is abundant as subcutis, mesentery, peritoneum, legs and sternum. All animals are susceptible but more frequent in adult females. Macroscopic appearance It s vary in size and shape. It is rounded or ovoid or pedunculated. They are single or multiple but well circumscribed and lightly encapsulated. The cut surface is smooth and soft and white or yellow in color. Its cut surface has a greasy or oily translucent appearance.

Microscopic pictures

• Lipoma is simply composed of fat cells shows great variation in shape and size. • The neoplastic cells composed of one large globule or several globules. • The nuclei are pushed to the peripheral. • The connective tissue bundles separated the globules.

Liposarcoma-2 • It is a rare malignant tumor of adipose tissue. It is seen in subcutis, sternum, and abdomen. • Microscopic picture • The cells contain small amount of fat. Liposarcoma is highly cellular and consists of round or ovoid cells. • The nuclei are round or ovoid with a single large eccentric nucleolus and rare mitotic figures. • Prognosis is fairly serious and metastasis is rare

Chondroma • It is an uncommon benign tumor of hyaline cartilage or from tissue suffered from metaplasia. Macroscopic appearance Hard well-defined lobulated tumor and well encapsulated. C/S: bluish-white and Size of chondroma is varied. It may contain foci of calcification. Microscopic appearance The cells arranged in multiple lobules of well-differentiated hyaline cartilage divided by strands of fibrous tissue. The neoplastic cells are located singly in lacunae. The cells are separated by hyaline matrix. The cells are small at the periphery, but large at center

Chondrosarcoma. 2 • It is an uncommon malignant tumor originates from cartilage. Macroscopic appearance It is large lobulated well-defined tumors It is firm, bluish grey but may contain pink fleshy areas. It is covered by thin capsule or may be partially encapsulated. Large areas of hemorrhages and necrosis may present. Microscopic appearance The cells are numerous varying from spindle to round and rhomboid in shape. The nuclei are variable in size and shape, hyperchromatic and showed mitotic The anaplastic cells invade the surrounding tissue and the lacunae are not formed. Some giant cells may be present. The blood vessels are ill developing beside area of necrosis and hemorrhages are seen.

Neoplasms of bone 1. Osteoma Osteoma is a rare benign tumor of osteoblasts of all species, Osteoma and exostosis are quite similar.

Macroscopic appearance Osteoma is generally slow growing small, circumscribed, encapsulated tumor. They are usually round or elliptical. Microscopic appearance Osteoma is similar to normal bone but differs in having less complete Haversian systems, which run at right angles to the bone angles to the bone axis

Osteosarcoma • It is the malignant tumor of osteoblasts which usually arise from periosteum. Macroscopic appearance The osteosarcoma is usually hard or fleshy and contains soft areas of bone spicules. The affected bones are easily broken due to demineralization. Microscopic appearance The neoplastic osteoblasts appeared as fusiform, polygonal or short spindle cells with ovoid hyperchromatic nuclei with numerous mitotic figures and acidophilic or basophilic cytoplasm. The stroma is ill developed and the blood vessels are poor developed forming blood spaces. The presence of bony structure helps to distinction between fibrosarcoma and chondrosarcoma.

)Giant cell tumor of bone (Osteoclastoma. 3 • It is rare malignant tumor originates from osteoclasts (bone macrophage) of cancellous bone in old animals. Macroscopic pictures The osteoclastoma is usually rounded or fusiform and variable in size and shape. The color is usually grayish pink with center areas of hemorrhages and necrosis. Microscopic pictures The tumor is consisting from spindle cells like osteosarcoma with large, dark staining fusiform nuclei. The characteristic feature is presence of large multinucleated giant cells of osteoclasts types (contains numerous nuclei which may be more than 50). The fibrous stroma is moderate.

F. Tumors arising from endothelial cells A. Hemangioma Hemangioma is benign tumors of endothelial cells that line blood vessels. • It should be distinguished from vascular hamartoma and telangiectasis.

According to the amount of cellular element and blood spaces we can divide hemangioma into

1. Capillary or plexiform hemangioma

Cavernous hemangioma. 2

Hemangioma hypertrophicum-3

Capillary or plexiform hemangioma. 1 • The tumor characterized by small to medium sized blood vessels and no great amount of cellular element. • It is the most common vascular tumors and most commons in skin, subcutis and mucous membrane. • Macroscopic pictures • The color is dark red and the size is varying from few millimeters to several centimeters in diameter. • Blood is oozing profusely with trauma. • The shape is variable with soft consistency. • Microscopic appearance • The tumor is consisted of thin walled capillaries lined with endothelial cells on basement membrane. • The capillaries may be empty or filled with erythrocytes. • The capillaries surrounded and separated with varying amount of collagen fibers. • The more solid tumor is more cellular with fewer blood spaces lined with several endothelial layers.

Cavernous hemangioma. 2 Hemangioma characterized by presence of large blood spaces. It seen in liver and spleen or any place formed from cavernae. • Macroscopic picture • It is soft ill defined spongy masses, bluish red in color and variable in size. • Sometimes, it compressible when connect with large vessel. • Microscopic appearance • Large irregular spaces lined by anaplastic cells and filled with blood are seen. Hemangioma hypertrophicum-3 It is tumor consists of large amount of cellular tissue and minimal .blood space

)Hemangiosarcoma (hemangioendothelioma-4 •

It is a malignant vascular tumor with numerous immature, pleomorphic endothelial cells that form blood field vascular spaces or masses of cells.

Macroscopic picture The size of tumor is varies greatly, non encapsulated, rubbery or spongy in consistency. The color is grayish red in color with dark red area Microscopic picture The tumor consists of anaplastic cells with large round, oval or spindle hyperchromatic nuclei. The cells tend to form vascular spaces. Both typical and atypical mitotic figures are present. The tumor may contain small space or cleft containing variable amount of blood, which help in distinction from fibrosarcoma.

B. 1-Lymphangioma It is rare benign tumor originates from endothelial lining of the lymphatic vessels. • Macroscopic appearance • It is usually soft, cystic and encapsulated. • Microscopic appearance • The tumor mass may form cords, cords with capillary sized spaces or group of spaces lined by endothelial cells separated by collagen fibers and filled with faint pink material (lymph). 2-Malignant Lymphangioma It is malignant tumor of endothelial lining of lymph vessels. It is similar to hemangiosarcoma with presence of pale eosinophilic fluid instead of blood.

C-Hemangiopericytoma is benign tumor orginated from pericytes

Tumors of hemopoietic and lymphopoietic tissues Lymphoproliferative (lymphoid)

Myeloproliferative )(myeloid

The hemopoietic tumor can be classified into five main groups 1; leukemia; 2-malignant lymphoma; 3-plasma cell neoplasms; 4-histocytoses; 5-Myeloproliferative disorders.

Leukemia • • • •

Leukemia is an umbrella term refers to malignant hemopoietic neoplasms that originate in the bones marrow and typically have significant number of neoplastic cells in blood. The neoplastic cells may be seed and infiltrate other organs such as liver, spleen and lymph nodes. Replacement of the bone marrow with neoplastic cells lead to some clinical finding regardless the types of leukemia as anemia hemorrhages and increase susceptibility to infection. The leukemia can be divided into

Acute myeloid and lymphoid leukemia

Chronic lymphoid or myeloid leukemia

Lymphoid leukemia It means that the replacement of bone marrow by anaplastic lymphoid cells besides the presence of anaplastic lymphocytes circulating in the blood vascular system. Myeloid Leukemia is neoplasms that involving the precursors cell of granulocyte series.

Lymphosarcoma or malignant. 2 lymphoma or lymphoma • Lymphomas are among the most common neoplasm in animals and originate from lymphocytes Lymphoma macroscopically can divided into 1-multicentric 2-thymic 3-alimentary 4-splenic and 5-cutaneous. Macrosc opic picture Multiple but may be solitary and sharply defined nodules. Grayish-white in color in all animals, but in chickens the color may be yellowish. Cut surface showed bulge lymphosarcomas and they are multiple. The involved lymphoid tissues are greatly enlarged.

Microscopic picture • The tissue architecture of the involved tissue may be over shadow by neoplastic lymphocytes. In all forms, the normal structure of the affected lymphoid tissue is completely disappears. • The normal arrangement of lymphocytes into follicles, corpuscles, cortex, medulla, sinuses and cords are completely distorted. The lymphosarcoma can be divided into several types according to different cytological forms. I:- Lymphosarcoma small cell type, where the tumor composed of mature lymphocytes mixed some time with large one. • ii:- Lymphosarcoma histocytic type, which consists of large lymphoblast with large round to ovoid nucleus. The chromatins are clumped and the nucleus contains one conspicuous nucleolus. The cytoplasm is scanty and basophilic.

iii:- Lymphosarcoma-reticulum cell type or stem is the most anaplastic one. It is poorly differentiated type, which made up of individual cells with irregularly outlined. The nuclei are large, round or oval with centrally placed nucleoli. Vi:- Hodgkin’s disease is a complex form of lymphosarcoma, which present mainly in human. Cases in animals are reported from time to time with proposed diagnosis of Hodgkin’s. Microscopically the tumor is distinguishable from malignant lymphoma by presence of diagnostic Reed-Sternberg cells. The cell is large and containing two nuclei with prominent nucleoli resample inclusion body (Owl eyed). The tumor is composed of histiocytes, fibroblasts, eosinophils and Reed-Sternberg cells. •3:- Plasma cell neoplasms (multiple myeloma) are a malignant neoplasm of plasma cells originating in bone marrow and often seeding in liver and spleen.

Tumors of muscles )(Myomas

• It is a general term used to describe tumors arises from both striated and smooth muscles. 1:- Leiomyoma Macroscopic picture Leiomyoma usually solitary but may be multiple. The tumor is well circumscribed by may not be capsulated The size is variable from few millimeters to several centimeters in diameter. The tumors are firm in consistency, spherical or elliptical in shape and pink in color. Ulceration of the surface of the tumor may occur if the tumor protruded into the lumen as in vagina.

• • • •

• Microscopic pictures The leiomyoma is consisting from bundles that may form whorls or appear wavy. The neoplastic cells are spindle-shaped cells containing elliptical shaped nucleus The later is rode shaped or cigar shaped and rich in chromatin and the nucleoli are not prominent.. Van Gieson’s stain should be used to determine the connective tissue, which stains red, while the muscle fibers stains yellow.

Miscellaneous tumors 1-Melanoma (malignant melanoma, )Melanosarcoma or melanocarcinoma

• It is a common malignant or at least temporary benign tumor of melanoblasts Susceptible animals and location It is common tumor in dog and horse and occurs in ox, pigs, chicken, sheep, cat and goat. Skin is the common site (specially ventral surface of the tail in white and gray horse) but may be seen iris and choroid of the eye

Macroscopic picture • The color is black, brown or gray depend on the concentration of melanin. • The highly malignant one is highly amelanotic. • The size and weight are variable. • The consistency is soft, firm or encepholoid according to the amount of connective tissue and necrosis. The cut surface is usually smooth, shiny and brown.

Leiomyosarcoma-2 Macroscopic picture • It is usually has large size, multi-cystic and fleshy pink in color. • Microscopic picture • The tumor is highly cellular with hyperchromatic nuclei and presence of mitotic figures. 3:-Rhabdomyoma Rhabdomyoma is a benign tumor originated from skeletal and cardiac muscles. Rhabdomyosarcoma It is a malignant tumor of striated and cardiac muscles.

Miscellaneous tumors 1-Melanoma (malignant melanoma, ) Melanosarcoma or melanocarcinoma

It is a common malignant or at least temporary benign tumor of melanoblasts Susceptible animals and location Macroscopic picture It depends on the stage of malignancy. The color is black, brown or gray The size and weight are variable. The consistency is soft, firm or encepholoid according to the amount of connective tissue and necrosis. The cut surface is usually smooth, shiny and brown.

Microscopic picture The tumor consists of irregular round, spindle or stellate cells (melanoblasts) which are closely backed together like segments of oranges with fibrous tissue trabeculae in between them. The cytoplasm tends to be basophilic and the nuclei have violet hue. • Brownish pigments (melanin) are usually found inside the melanoblasts cytoplasm which may be overshadowing the detail of cells. • In a melanotic melanoma most cells are highly anaplastic and contain no pigments.

Mesothelioma • It a rare neoplasm arises from the mesotheilal cells covered the serous membrane. • It was recorded in horse, cow, dog and cat. Macroscopic appearance The tumor appears as nodular diffuse growth on serous membrane.

Microscopic appearance The tumor appears as carcinoma or fibrosarcoma. The tumor form arboreal fibrous tissue core covered with cuboidal mesotheilal cells focally replaces the serous membrane and adjacent tissue

Teratoma • Teratoma is a tumor composed of multiple tissue derived from more than one germ cell layers (at least two or three embryonic germ layers). Susceptible animals and location It is a rare tumor but observed in all animal species horse. It is rare in dog, chicken, ox and pig. It occurs mostly in ovary and testis. Macroscopic picture It is usually round, ovoid or irregular in shape and may be encapsulated. The tumor consists of solid area or cysts which contain semisolid greasy material, hair and teeth. Some teratoma may contain cartilage and bone.

Microscopic picture • A benign teratoma consists of well differentiated tissue. All tissue may be present without any tendency to form organ. • Ovarian teratoma is usually well differentiated and benign but testicular teratomas are always malignant. • The tumor consists of cyst, which lined by stratified squamous, cuboidal or columnar epithelium, epidermal cells, and skin appendages and contains cartilage, bone, teeth and hair besides sebaceous secretion. • In some cases the cysts contain one or more teeth and called dentigerous cyst.