Atlas of Diagnostic Cytology in Small Animals

PRESENTATION

Elena Martínez de Merlo

BROCHURE

ATLAS OF DIAGNOSTIC CYTOLOGY

ATLAS OF DIAGNOSTIC CYTOLOGY in Small Animals

in Small Animals Elena Martínez de Merlo

Elena Martínez de Merlo

ATLAS OF DIAGNOSTIC CYTOLOGY in Small Animals

ATLAS OF DIAGNOSTIC CYTOLOGY in Small Animals

Atlas of Diagnostic Cytology in Small Animals

Elena Martínez de Merlo

AUTHOR: Elena Martínez de Merlo.

FORMAT: 22 × 28 cm.

NUMBER OF PAGES: 192.

NUMBER OF IMAGES: 355.

BINDING: Hardcover.

RETAIL PRICE

€83

eBook included

Atlases of cytology are an essential tool in small animal practice.

Diagnostic cytology, which is used extensively in routine clinical practice, requires the most comprehensive cell identification possible. This is best achieved with the help of numerous images that reflect the most characteristic and distinguishing features of the different cytological patterns, and this book will therefore be of great use to the reader in the diagnostic process of many pathologies.

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Atlas of Diagnostic Cytology in Small Animals

Presentation of the book This book intends to complement the contents of the Atlas de citologĂ­a clĂ­nica del perro y del gato (Atlas of clinical cytology in cats and dogs) , also published by Servet. Generally, similar concepts can be applied to the cytological interpretation of most diseases.

Therefore, this work is essentially based on a large collection of images that support the theoretical cytological bases explained in the preceding book. However, unlike the previous atlas (and the majority of atlases published by other publishers) it follows an approach that is organised according to the most common diseases rather than by organs or tissues. The aim of this book is therefore to allow readers to find images in each chapter that reflect different aspects of the given pathology, regardless of the lesion’s location.

This novel approach means that as soon as veterinary surgeons suspect a specific pathology, they can go directly to the corresponding chapter, which features images covering all possible aspects of the disease as well as both common and differential findings, and therefore they may confirm or rule out their suspicion. In the case of neoplasms, it also provides information about what they need to look for in other locations to establish the clinical stage, since the pathology may take on a different appearance at the site of metastasis than that of the primary tumour. The atlas also includes images that, while similar to the pathology considered in the specific chapter, do not correspond to the disease in question, which is essential to avoid misdiagnoses.

The book provides the descriptive written information necessary to diagnose each pathology. It does not elaborate on the basic concepts of cytological interpretation (already explained in the previous book), but rather delves into specific and differential aspects. A large portion of the text is devoted to describing the images throughout the atlas.

Atlas of Diagnostic Cytology in Small Animals

The author Elena Martínez de Merlo

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Dr Martínez holds a degree (1987) and a PhD (1993) in veterinary medicine from the Complutense University of Madrid (UCM). She has been an assistant lecturer at the Department of Veterinary Medicine and Surgery of the UCM since 1998. She performs clinical work at the Complutense Veterinary Teaching Hospital (HCVC), and is the head of the Oncology and Diagnostic Cytology Clinic of the HCVC Clinical Pathobiology Service.

Dr Martínez is the author of Atlas de citología clínica del perro y del gato (Atlas of clinical cytology in cats and dogs) published by Servet (2008) and Manual práctico de oncología en pequeños animales (Practical manual of small animal oncology; 2011 and 2014). She is the director of the UCM’s continuing education diploma programme “Cytological Interpretation in Small Animals” (60 hours), which she has taught on 11 occasions. She is certified in oncology by the Spanish Small Animal Veterinary Association (AVEPA) and was the president of AVEPA’s Group of Veterinary Oncologists (GEVONC) from when it was founded in 2011 until April 2014. She has spoken at various national and international congresses, and taught many courses and seminars about oncology and diagnostic cytology. In addition, she is the author or coauthor of articles on oncology and the clinical application of diagnostic cytology in both Spanish and international journals.

ATLAS OF DIAGNOSTIC CYTOLOGY in Small Animals Elena Martínez de Merlo

Table of contents 1. Citology of inflammation Identification of inflammatory cells Neutrophils Lymphocytes Eosinophils Mast cells Plasma cells Macrophages

Definition of inflammatory pattern Identification of microorganisms Presence of tissue cells in an inflammatory cytology sample

2. Cytology of noninflammatory/non-neoplastic lesions Hyperplastic processes Degenerative processes Degenerative processes in the liver Degenerative processes in the joints

Extramedullary haematopoiesis (EH)

3. Cytology of mast cell tumours Diagnostic criteria for mast cells tumours Estimation of the degree of differentiation Diagnostic criteria for metastatic mast cell tumours

4. Cytology of lymphoma Diagnosis of lymphoma in lymph node cytology Diagnostic quality of lymph node samples Diagnosis of lymphoma Cytological diagnosis of the type of lymphoma

Diagnosis of lymphoma in other cytological examinations

5. Cytology of histiocytic diseases Identification of histiocytic cells Cytological characteristics of histiocytomas Cytological characteristics of histiocytic sarcomas

Canine reactive histiocytosis/feline progressive histiocytosis

6. Cytology of sarcomas Cell lineage identification Sarcoma grading Low grade sarcoma High grade sarcoma Undetermined grade

Identification of the type of sarcoma Vessel wall and nerve sheath tumours (haemangiopericytomas and schwannomas) Myxosarcoma/synovial sarcoma Feline injection-site sarcoma (FISS) Liposarcoma Muscle tumours Osteosarcoma Haemangiosarcoma

7. Cytology of epithelial tumours Cell distribution Cell morphology Cytoplasmic vacuoles Malignancy criteria Specific considerations regarding certain epithelial tumours Canine mammary tumours (CMT) Basal cell tumours Hepatocellular carcinomas

Difference between reactive mesothelial cells, mesothelioma and carcinomatosis

8. Cytology of melanoma Cytological assessment of melanotic melanomas Cytological assessment of amelanotic melanomas Cytological considerations for metastatic melanomas

References

03

Cytology of mast cell tumours

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Cytology of mast cell tumours Cutaneous mast cell tumours are very common in dogs. In cats, mast cell tumours affect the spleen and gastrointestinal tract in 50 % of cases. With this tumour type, cytology is sufficient to establish a definitive diagnosis (in 92–96 % of cases), since the characteristics of mast cells are easily identifiable.

The objectives of cytology in the diagnosis of this tumour are as follows: 1. Verify that the tumour is indeed a mast cell tumour.

2. Estimate the degree of differentiation.

3. Identify possible regional or distant metastases.

DIAGNOSTIC CRITERIA FOR MAST CELL TUMOURS Mast cells are small-to-medium-sized round cells, with a round nucleus and abundant cytoplasm containing reddish-purple metachromatic granules. Degranulation phenomena occur in response to different stimuli, resulting in the release of vasoactive substances contained within the granules (Fig. 1).

The presence of cytoplasmic granules is the main criterion for identification of a mast cell.

These cells should be distinguished from other cells that contain granules or pigment, particularly goblet cells (in tracheal washes) and large granular lymphocytes, both of which contain granules that are more pinkish-red than purple. While most goblet cells are elongated, they can occasionally be rounded, therefore generating confusion (Fig. 2). Granular lymphocytes can be distinguished by their greater nucleus:cytoplasm ratio and the morphology of the granules (Fig. 3).

Mast cells are widely distributed, and increase in number in numerous inflammatory and reactive processes. For a diagnosis of cutaneous mast cell tumour, the mast cell population should exceed 50 % of the total cell population.

In addition to mast cells, mast cell tumours contain other cell types, sometimes in large numbers: ■ The second most commonly encountered cell type is the eosinophil. For this reason, it is necessary to determine which is the predominant cell type (eosinophilic lesion versus mast cell tumour) and which is secondary (Fig. 4). Although the percentage of eosinophils can be very high in mast cell tumours, mast cells must predominate. The percentage of eosinophils is not indicative of the degree of differentiation of a mast cell tumour. Their presence is very useful to orient the diagnosis when they accompany an undifferentiated population of round cells.

■ Conjunctive cells are commonly observed in mast cell tumours. These are fibroblastic cells that are activated by mast cell mediators, and exhibit obvious dysplastic signs that should not be attributed to neoplastic changes. Although their number cannot be used as an indicator of tumour grade, they are more abundant in well-differentiated mast cell tumours (Figs. 5 and 6).

Degranulation can be very marked. Cytology of most well-differentiated mast cell tumours typically reveals numerous extracellular granules, which should not be confused with bacteria or other microorganisms (Figs. 7 and 8).

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Atlas of Diagnostic Cytology in Small Animals

Figure 1. Mast cells. One is intact and three are degranulating.

Figure 2. Goblet cell (arrow) in a tracheal wash sample (not to be confused with a mast cell).

CyTOLOGy OF MAST CELL TUMOURS

Figure 3. Large granular lymphocyte lymphoma (cat). The cell and granule type differ to those of mast cells.

Figure 4. Eosinophilic inflammation. Although two very granulated mast cells are observed (arrows), the predominant cell population is eosinophilic (with macrophages and activated conjunctive cells).

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Atlas of Diagnostic Cytology in Small Animals

Figures 5 and 6. Well-differentiated mast cells accompanied by eosinophils and conjunctive cells with dysplastic changes (which should not be attributed to malignancy).

Figure 5.

Figure 6.

CyTOLOGy OF MAST CELL TUMOURS

Figure 7. Well-differentiated mast cell tumour. Note the many extracellular granules resulting from cell degranulation.

Figure 8. Well-differentiated mast cell tumour. Note the presence of Leishmania amastigotes (arrows), which can be confused with granules.

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Atlas of Diagnostic Cytology in Small Animals

ESTIMATION OF THE DEGREE OF DIFFERENTIATION Although there is consensus on the role of cytology as a fundamental tool for the diagnosis of mast cell tumour, its use as a means of estimating the degree of differentiation is controversial. Histology is the only technique that can be used to grade mast cell tumours (Patnaik or Kiupel criteria), although cytology can be used to estimate the grade as a first step in the diagnostic protocol.

Estimation of the degree of differentiation can be based on the following criteria1: ■ Number of granules (many, few, mixed).

■ Absence or presence of nuclear pleomorphism (nonround nuclei).

■ Absence or presence of mitotic figures.

■ Absence or presence of binucleated or multinucleated cells.

■ Absence or presence of karyomegaly (>50 % variation in nuclear size).

Based on the evaluation of these parameters a diagnostic algorithm can be established.

Mast cells containing few granules

YES

NO At least two of the following criteria are fulfilled: Mitoses ■ Nuclear pleomorphism ■ Binucleation or multinucleation ■ Karyomegaly ■

YES

NO

High grade

Low grade

Other studies have proposed that mast cell tumour grade can be estimated based only on nuclear characteristics, according to the criteria of the Kiupel grading system 5.

From this author’s point of view, cytology allows differentiation between two main tumour types: ■ Clearly well-differentiated mast cell tumours, in which the majority of mast cells contain so many granules that the nucleus is not visible, but when it is visible (in degranulated cells) it is small, rounded, and homogeneous across cells (Fig. 9–12).

■ Clearly undifferentiated mast cell tumours, in which the majority of mast cells contain few granules and/or the nuclear atypia described in the algorithm is evident (Figs. 13–18). The presence of binucleated or multinucleated cells and karyomegaly are the nuclear criteria that best correlate with a decrease in survival time. Mitoses, the presence of which is an important

CyTOLOGy OF MAST CELL TUMOURS

indicator of undifferentiation, are not usually observed in sufficient numbers. Nuclear pleomorphism is too subjective a criterion and should not be considered as the sole means of determining undifferentiation. In mast cell tumours the granules tend to be located at the opposite pole to the nucleus.

Figure 9.

Figure 10.

Figure 11.

Figures 9–11. Images showing mast cell tumours (estimated grade, well-differentiated). The mast cells contain numerous granules that mask the nucleus.

Figure 12. Although the mast cells do not contain many granules (probably due to degranulation), the nuclei are homogeneous, and none of the criteria of the diagnostic algorithm are fulfilled.

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Atlas of Diagnostic Cytology in Small Animals

Figures 13–17. Images showing mast cell tumours (estimated grade, undifferentiated). In addition to the low level of granulation, marked nuclear atypia (karyomegaly, multinucleation, mitoses) is evident (arrows).

Figure 13.

Figure 14.

Figure 15.

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