Uncommon to Complex Clinical Cases in Small Animal Dermatology

PRESENTATION

BROCHURE

UNCOMMON TO COMPLEX Clinical Cases

Carla Dedola Giordana Zanna

LOMO PENDIENTE DE CALCULAR

UNCOMMON TO COMPLEX Clinical Cases

in Small Animal Dermatology

Carla Dedola Giordana Zanna

LOMO PENDIENTE DE CALCULAR

in Small Animal Dermatology

eBook

available

Carla Dedola Giordana Zanna

in Small Animal Dermatology

UNCOMMON TO COMPLEX Clinical Cases

Uncommon to Complex Clinical Cases

UNCOMMON TO COMPLEX Clinical Cases

Carla Dedola Giordana Zanna

PY097565_Uncommon to Complex Clinical Cases in Small Animal Dermatology CUB SERVET.indd 3

This book has been created for everyone passionate about veterinary dermatology. Written by veterinary experts, this resource will explore the diagnostic thinking process. This practical book describes complex dermatological clinical cases through the evaluation of their clinical presentation, results of diagnostic procedures and treatment strategies.

Fully illustrated with colour pictures, it also includes tables and clinical keys.

TARGET AUDIENCE:

13/7/20 12:28

ESTIMATED

RETAIL PRICE ✱ Small animal vets.

Dermatology ✱ Veterinary nurses ✱ Veterinary students FORMAT: 22 x 28 NUMBER OF PAGES: 192 NUMBER OF IMAGES: 175-200 approx.

BINDING: hardcover

€49

ESTIMATED PUBLISHING DATE:

September 2021

Authors CARLA DEDOLA She graduated in Veterinary Medicine from the University of Sassari (Italy) in 2001. She is a Diplomate of the European College of Veterinary Dermatology.

GIORDANA ZANNA She graduated in Veterinary Medicine from the University of Bari (Italy) in 2000 and obtained her PhD from the Universitat Autònoma de Barcelona (AUB) in 2010. She is a Diplomate of the European College of Veterinary Dermatology.

KEY FEATURES:

➜ Practical approach to differential diagnosis in dermatology in both dogs and cats. ➜ Written by two experienced, board-certified specialists in dermatology. ➜ Case-based format, clear and well-illustrated.

Presentation of the book This book aims to present a range of complex dermatological clinical cases in both dogs and cats. “Complex� means all those situations for which it is not easy or straightforward to find a solution or an answer. Starting from this point, the authors selected several challenging dermatological cases for which reaching a final diagnosis was not as simple or linear as in other situations. In those cases, the difficulties might have been arisen from the unusual clinical presentation, from the unexpected results of the diagnostic tests or from the lack of a positive answer to a therapeutic protocol that was considered adequate for that specific case. The complexity of the cases might derive from the patient, its genotype or phenotype, from its immunological status, from the presence of comorbidity or simply from the fact that the clinicians will not expect that specific disease in that patient for different reasons (i.e. not predisposed breed, unusual age).

The readers will go through the development of the cases following the thoughtful way explained by the authors themselves. Each case has a problem-based approach, incorporating its respective history, physical and dermatological examinations, diagnostic tests and results, treatment and outcome. The authors will end up with some considerations as well as the key elements for a better interpretation of each specific case.

Uncommon to Complex Clinical Cases in Small Animal Dermatology

The authors Carla Dedola Dr. Carla Dedola graduated in Veterinary Medicine from the University of Sassari (Italy) in 2001. After completing her degree, she worked as a general practitioner in a private veterinary clinic in Monza (Italy). There, she started to develop her passion in small animal dermatology. In 2007, she obtained a position as resident in dermatology at the Royal (Dick) School of Veterinary Studies at the University of Edinburgh (Scotland). In 2010, she sustained and passed the European College exam in Veterinary Dermatology becoming a European Diplomate in Veterinary Dermatology. She has been secretary of the Italian Society of Small Animal Dermatology (SIDEV) in Italy from 2014 to 2019. Since 2011, she has been working as freelance in Sardinia (Italy), collaborating with numerous veterinary clinics over the territory. She is the director and the scientific mentor of dermatological courses organized by the Italian Companion Animal Veterinary Association (SCIVAC).

Dr. Giordana Zanna graduated in Veterinary Medicine from the University of Bari (Italy) in 2000. After working in general practice in Italy and doing externships at Universities of Liverpool and Bristol (UK), she undertook a residency in veterinary dermatology at Universitat Autònoma de Barcelona (UAB) in Spain, gaining her diploma of the European College of Veterinary Dermatology in 2010. At the same Institution, she fulfilled her PhD studies on the pathogenesis of mucinosis-hyaluronosis in Shar Pei dogs in 2010. Vice president of the Italian SIDEV and secretary of the SCIVAC, she is the director and scientific mentor of the Italian course of Dermatology. Giordana now works at Instituto Veterinario di Novara (Italy) as a private practice dermatology specialist, and she regularly provides lectures in national courses both in Italy and Spain and gives talks at international conferences.

She has written several articles published in national and international journals and she also enjoys research with a special interest in non-invasive diagnostic techniques such as dermoscopy.

hkeita/shutterstock.com

Giordana Zanna

Table of contents Case 1. Generalized partial alopecia with scaling in a dog Case 2. Alopecic, ulcerative and erythematous plaque on the tarsal region in a cat Case 3. Severe ulcerative dermatitis in a dog Case 4. Erosive and scaling dermatoses in a cat Case 5. Muco-cutaneous ulcerative dermatitis in a dog Case 6. Ulcerative multifocal dermatitis in a dog Case 7. Generalized pustular dermatitis in a dog Case 8. Nodular dermatitis in a dog Case 9. Generalized alopecia in a cat Case 10. Proliferative plaque-like lesions in a dog Case 11. Generalized scaling dermatoses in a dog Case 12. Multifocal alopecia in a dog Case 13. Non-inflammatory alopecia affecting only the black-haired coat in two dogs Case 14. Exfoliative dermatitis in a cat Case 15. Nodular dermatitis in a dog Case 16. Multifocal, polycyclic erythematous lesions with epidermal collarette in a dog Case 17. Erosive-ulcerative dermatitis in a seasonal atopic dog Case 18. Mucocutaneous ulcerative lesions of the nasal planum in a dog Case 19. Severe necrotizing dermatitis on a dog’s leg Case 20. Ulcerative dermatitis in a cat

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+34 976 461 480

UNCOMMON TO COMPLEX Clinical Cases

in Small Animal Dermatology

Carla Dedola Giordana Zanna

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CASE 1. GENERALIZED PARTIAL ALOPECIA WITH SCALING IN A DOG SIGNALMENT

INTRODUCTION This case represents an opportunity for every clinician to recall the importance of following step by step a correct diagnostic approach, which is fundamental to confirm or dismiss a clinical suspicion. The diagnosed disease is not particularly uncommon or difficult to recognize, but it could have been missed or confused with another condition similar in some clinical aspects and much more commonly described in the reported dog breed.

CLINICAL HISTORY

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Species: dog

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Breed: Pomeranian

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Age: three years old

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Sex: female

of small white adherent scales and hair casts on the trunk, the head and both ear pinna (Fig. 2).

Differential diagnosis Based on the signalment, history and clinical findings, the differential diagnosis lists as follow: ■ Idiopathic granulomatous sebaceous adenitis.

■ Leishmaniosis.

■ Hair cycle arrest (alopecia X).

■ Demodicosis.

■ Generalized dermatophytosis.

The dog began to show hair loss and presence of scales approximately six months before consultation. The systemic antibiotic treatment prescribed by the referring veterinarian, amoxicillin and clavulanate at a dose of 15 mg/kg (BW) two times daily for 14 days, did not helped in the hair regrowth. The hair loss started from the head and extended to the trunk, the tail and the extremities.

EXAMINATION GENERAL PHYSICAL EXAMINATION No abnormalities were detected.

DERMATOLOGICAL EXAMINATION The examination revealed a diffuse partial alopecia and lack of secondary hairs. Poor, dry and dull hair coat was also observed (Fig. 1). A closest observation was helpful to identify the presence

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Figure 1. Generalized partial alopecia, especially evident on the trunk and the legs (arrow). Secondary hairs are lacking, with a lusterless hair coat.

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UNCOMMON TO COMPLEX CLINICAL CASES IN SMALL ANIMAL DERMATOLOGY

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Figure 2. Small adherent scales on the head (a) and hair casts and scales visible on both ear pinnae (b-c).

DIAGNOSTIC TESTS

RESULTS

During this case, it was decided to perform: Microscopic hair examination: this is considered the most helpful test to observe hair shaft and hair bulb in case of suspicion of a disease affecting those structures. Moreover, although this is not considered the gold standard, this test makes possible to identify Demodex mite and fungal hyphae or spores.

■ Deep skin scraping: it is considered the gold standard test for the diagnosis of demodicosis. The material was collected and placed on a slide with some other mineral oil and a coverslip on the top. It was examined with the low-power objectives of the microscope (4x and 10x).

■ Fungal culture: some hairs and scales were collected by plucking and scraping and send to a specialized laboratory in order to perform a fungal culture.

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Microscopic hair examination: keratin debris accumulation on hair shaft with hairs often clumping together was observed; those findings are compatible with the so-called hair casts (Fig. 3) (see the key element of the case). The majority of the hair bulbs were in the telogen (hair cycle

As part of an exhaustive physical examination, and because leishmaniosis was one of the considered differential diagnosis, the following further tests were performed: ■ Complete blood count (CBC).

■ Serum biochemical profile.

■ Serological immunofluorescence antibody test (IFAT) for Leishmania antibodies.

Multiple skin biopsies, planned in case a diagnosis was not reached after performing the previously cited tests.

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Figure 3. Hair cast of keratosebaceous debris surrounding numerous hair shaft (4x).

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CASE 1. GENERALIZED PARTIAL ALOPECIA WITH SCALING IN A DOG

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arrest) phase, although some hairs in anagen (active hair growth) phase were also observed.

Skin scrapings were negative for the presence of Demodex mites and fungal elements.

Fungal culture did not identify any pathological growth.

Blood analysis. CBC and biochemistry profile were unremarkable and Leishmania antibody titer was negative.

On histopathological skin samples, the epidermis showed the presence of a lamellar orthokeratotic hyperkeratosis with a basketwave apperance. Multiple follicular plugging with

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prominent follicular keratoses were also observed. Sebaceous glands were not present and a lymphocytic and histiocytic inflammatory infiltrate was present on their behalf in some hair follicle compound (Fig. 4).

All the findings were consistent with a final diagnosis of idiopathic granulomatous sebaceous adenitis.

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Figure 4. Histopathological findings. Epidermal basketweave, lamellar orthokeratotic hyperkeratosis (a-b; black arrow in b) and multifocal follicular keratoses (b-c red arrow), together with a complete absence of sebaceous glands and occasional lymphocytic and histiocytic inflammatory infiltrate presence on their behalf (b-c- green arrow). Inflammatory infiltrate present on behalf of sebaceous gland (d).

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UNCOMMON TO COMPLEX CLINICAL CASES IN SMALL ANIMAL DERMATOLOGY

TREATMENT AND OUTCOME

CONSIDERATION

The dog was initially treated with oral cyclosporine A (CsA) at the dose of 5 mg/kg once daily, together with shampoo containing sulphur, zinc gluconate, lactic and salicylic acid once weekly and soak with propylene glycol diluted by 50 % with water once daily.

After two months of treatment, a marked improvement was noticed: hairs were growing back and scales were reduced by 75 %. The CsA was given at the same dosage but every 48 hours as opposed to the initial daily treatment. Rechecks were planned every 30–60 days, unless needed differently.

The dog showed a partial relapse during the maintenance treatment which consisted of a long term dosage of 5 mg/kg of CsA every 72 hours, together with diluted propylene glycol soak every other day and shampoo once weekly. The general aspect of the hair coat was improved although it never returned completely to normal; the scaling dermatitis was well controlled but it relapsed occasionally when the owner tended to neglect the topical treatment.

Although no specific diagnostic difficulties were found, some further considerations should be taken into account. Firstly, the clinical presentation of the dog, together with the breed, could have mislead the clinician towards a diagnosis of hair follicle arrest (alopecia X), highlighting the importance of an adequate performance of the diagnostic procedures in order to confirm a clinical suspicion. Another thing to point out it is the necessity to carry out a careful and close evaluation of the skin lesions and their distribution. In fact, hair casts as well as the involvement of the head and the ears have not been described to be present as typical lesions in dogs suffering from hair follicle arrest. All these aspects have therefore guided the authors in the selection of the appropriate diagnostic test to reach an early diagnosis and avoid unnecessary tests.

The clinical presentation of the dog together with the breed could have misled the clinician towards a diagnosis of hair follicle arrest.

THE KEY ELEMENT OF THE CASE Hair casts are accumulations of keratin debris that adhere to the hair shaft extending above the follicular ostia (Fig. 5).

Hair casts are considered a primary lesion in disorders of cornification, especially in sebaceous adenitis, but can be also found in demodicosis and dermatophytosis. In this case, if hair casts had not been present, hair cycle arrest would have probably been the first differential due to the breed of the dog (Fig. 6).

Figure 5. Dermoscopic images showing hair casts on hair shaft.

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Figure 6. Chow Chow with hair follicle arrest (alopecia X). Hair coat is poor and there is complete lack of secondary hairs. Hyperpigmented alopecic multifocal areas are visible on the neck, the flank and the thigh.

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CASE 1. GENERALIZED PARTIAL ALOPECIA WITH SCALING IN A DOG

IDIOPATHIC GRANULOMATOUS SEBACEOUS ADENITIS BRIEF DESCRIPTION OF THE DISEASE Idiopathic granulomatous sebaceous adenitis is a disease characterized by an immunological reaction, most probably due to natural cell-mediated immunity, directed against the dog´s sebaceous glands, which can result in their partial or complete destruction.

Idiopathic granulomatous sebaceous adenitis is an uncommon disease in dogs and rare in cats. The age of onset can vary widely, from young to middle-aged dogs, and there is a reported breed predilection for standard poodles, Akitas, Samoyeds and Vizslas, although mongrels and other breeds can be affected as well.

Clinical lesions can be limited to the presence of scales and partial alopecia, especially in the early phase, or can occur in more severe forms showing prominent hair casts, extended alopecic areas and signs of secondary infections, possibly caused by bacteria and/or yeast. The hair coat is poor and dull, and it can become straight from curly in poodles. Otitis externa can be present and, in some cases, it can appear as a unique early clinical sign. The lesions are initially distributed on the dorsum and the head; ear pinnae are also typically involved (Fig. 7).

Finally, they tend to generalize over time.

Principal differential diagnosis includes demodicosis, dermatophytosis, follicular dysplasia and, in endemic areas, leishmaniosis. The diagnostic confirmation can be reached with the aid of histopathology: in the early phase, a granulomatous to pyogranulomatous inflammatory infiltrate targeting the sebaceous glands with follicular keratoses can be observed; in late stages of disease, a complete destruction of these glands together with follicular atrophy and scant inflammatory infiltrate may be likely to occur.

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TREATMENT Mild cases of sebaceous adenitis can be treated with: ■ Topical treatment using keratolytic shampoo containing ingredients such us sulphur or salicylic acid together with emollient and hygroscopic rinses containing glycerine, urea, colloidal oatmeal, sodium lactate and lactic acid.

■ Daily spray or rinses with propylene glycol diluted with water to 50-75 % which has been demonstrated to work well in controlling the clinical lesions.

■ Essential fatty acids omega-6 and omega-3 given orally have been shown to be helpful in managing all cases. For this reason, they should always be part of the therapeutic protocol.

In more severe cases, a systemic treatment is necessary: ■ Ciclosporin A (CsA) is nowadays the treatment of choice, given at a dose of 5 mg/kg/day until a 50 to 75 % of improvement have been reached, and then reduced to the most efficacious dosage.

■ Natural vitamin A at a dose of 10,000 to 30,000 IU/day has showed a good response in 80 % of patients treated.

■ Cases not responding to CsA can be treated with synthetic retinoids (i.e. isotretinoin 0.8-3.5 mg/kg/day or etretinate 0.7-1.8 mg/kg/day). However, the high costs and the serious potential side effects make these drugs difficult to be used.

The aim of the therapy is to keep the disease under control.

Rarely dogs go back to normal and many of them show relapse even when receiving therapy. It could be convenient to advise systemic treatment also in mild initial cases, as this seems that this may be the only way of getting back functional sebaceous glands.

Figure 7. Idiopathic granulomatous sebaceous adenitis lesions are distributed initially on the dorsum and the head. Ear pinnae are typically involved.

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UNCOMMON TO COMPLEX CLINICAL CASES IN SMALL ANIMAL DERMATOLOGY

Sebaceous adenitis due to canine leishmaniosis

BIBLIOGRAPHY

Sebaceous glands can be involved and destroyed in other dermal inflammatory processes apart from idiopathic sebaceous adenitis. Differentiation of sebaceous adenitis due to canine leishmaniosis from the idiopathic form may be particularly challenging.

1. BarDagi M, fonDevilla D, Zanna g, ferrer l. Histopathological

Direct identification of the Leishmania amastigotes in the tissue can be difficult, especially if their number is low. On histopathological examination, nodular and diffuse dermal infiltrate and epidermal and subepidermal lesions have been reported to be present in sebaceous adenitis secondary to canine leishmaniosis, while in the idiopathic form, the inflammation is generally restricted to the sebaceous glands and it is associated with epidermal hyperkeratosis and follicular keratosis.

w, lineK M. A multicentre placebo-controlled clinical trial on the

differences between canine idiopathic sebaceous adenitis and canine leishmaniosis with sebaceous adenitis. Veterinary Dermatology 2010; 21: 159-165.

2. lortZ J, favrot C, MeCKlenBurg l, nett C, rĂœfenaCHt s, seewalD efficacy of oral ciclosporin A in the treatment of canine idiopathic sebaceous adenitis in comparison with conventional topical treatment. Veterinary Dermatology 2010; 21: 593-601.

3. Miller wH, griffin Ce anD CaMpBell Kl. Muller and Kirk’s Small Animal Dermatology VII. Miscellaneous Skin Diseases. 2013: 695-699 4. siMpson a, MCKay l. Applied dermatology: sebaceous adenitis in dogs. Compendium: Continuing Education for Veterinarians.

2012; 34: 1-7.

5. Sousa CA. Sebaceous adenitis. Veterinary Clinics of North America Small Animal Practice. 2006; 36: 243-249.

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CASE 2. ALOPECIC, ULCERATED AND ERYTHEMATOUS PLAQUE ON THE TARSAL REGION IN A CAT SIGNALMENT

INTRODUCTION This case, representative of a relatively rare and aggressive condition in cats, could be wrongly interpreted if a predefined sequence of diagnostic steps is not followed. For this reason, the aim of this case presentation is to describe the clinical–diagnostic key elements and the useful information necessary to reach the final diagnosis.

CLINICAL HISTORY The cat was admitted for the evaluation of an ulcerated, erythematous and alopecic lesion of 45 days progression localized at the tarsal region of its left hind limb. It had started as a plaque prior to referral and had increased progressively in size over time. A bacterial infection had been suspected by the referring veterinarian. The initial treatment included 14 days of antibiotic therapy (amoxicillin and clavulanate) at dose of 20 mg/kg (BW), PO, two times daily and chlorhexidine spray 4% without evident clinical improvement. The owner also reported lameness and weight over the last few days.

EXAMINATION GENERAL PHYSICAL EXAMINATION Upon presentation, pain was evoked by palpation of the affected limb. An enlargement of the tributary popliteal lymph node was observed. A low body condition score (4/9)

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Species: cat

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Breed: domestic shorthair cat

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Age: 14 years old

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Sex: male

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Lifestyle: outdoor

and increased respiratory effort (labored breathing) were also detected.

DERMATOLOGICAL EXAMINATION An alopecic, ulcerated and erythematous plaque-like lesion extending laterally and an ulcerated mass-like lesion extending medially and ventrally to the left hind limb were detected at the tarsal region and the surrounding area (Fig. 1 a-b and Fig. 1c, respectively). Exudation with crust formation was also observed.

Differential diagnosis Based on the signalment, history and clinical findings, the differential diagnosis list as follow: ■ Neoplastic process: mast cell tumor, cutaneous lymphoma and/or plasma-cell derived tumor.

■ Infectious disease: including viral, bacterial, fungal and/or mycobacterial infections.

■ Eosinophilic granuloma as a cutaneous reaction pattern.

DIAGNOSTIC TESTS During this case, it was decided to perform: Skin citology: cutaneous and subcutaneous masses are readily accesible for fine-needle aspiration and citology in general, representing a powerful tool for evaluation of these lesions.

Fine needle aspirate samples together with direct impression smears of underside of a crust were collected from the skin.

■ Fine needle aspiration cytology of the enlarged left popliteal lymph node.

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UNCOMMON TO COMPLEX CLINICAL CASES IN SMALL ANIMAL DERMATOLOGY

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As part of an exhaustive examination and to determine any subsequent risk level in that elderly and infirmed patient, were performed and planned: ■ Complete blood count (CBC).

■ Serum biochemical profile.

■ Urinalysis ■ Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) status.

■ Abdominal and thorax radiography.

■ Ultrasonography.

■ Bone marrow aspiration.

■ Organ cytologic or histologic evaluation with immunohistochemistry ■ Bacterial culture, susceptibility testing and/or fungal culture.

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RESULTS ■

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Figure 1. Aspect of left hind limb (a-c). An alopecic, ulcerated and erythematous plaque-like lesion extending laterally and a mass-like lesion ventrally to the left hind limb (at the tarsal region and the surrounding area).

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Skin citology: the cytological sample collected from the skin showed a neutrofilic inflammation with degenerate neutrophils, presenting both intracellular and extracellular cocci.

Sparse round cells with basophilic cytoplasm were also observed.

Lymph node citology: cytology from the lymph node was highly cellular, most of the cells were intermediate to large round cells with round to oval-eccentric nuclei and finely clumped chromatin; variably distinct nucleoli and scant to moderate amount of basophilic cytoplasm were also detected. Occasionaly, mitotic figures were also observed.

Small lymphocytes were present on the background possibly

Figure 2. Lymph node citology. Presence of intermediate to large round cells with round to oval-eccentric nuclei and finely clumped chromatin and variably distinct nucleoli (100x).

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CASE 2. ALOPECIC, ULCERATED AND ERYTHEMATOUS PLAQUE ON THE TARSAL REGION IN A CAT

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coming from the residual normal population of the same lymph node (Fig. 2).

Blood and urinalysis: thee cat was anemic (hematocrit [HCT] < 30 %; range, 28.2 % to 52.7 %) but no other remarkable findings were detected. Negative results for either FeLV or FIV were also reported.

Imaging diagnostic: multifocal enteropathy, mesenteric lymphadenopathy and multifocal liver disease were detected on abdominal ultrasound (Fig. 3a), whereas a diffuse broncho-interstitial disease suggestive of outcomes of chronic feline bronchopathy was observed on thorax radiography (Fig. 3b). Ultrasonographically guided fine-needle aspiration was performed on liver and mesenteric lymph nodes; suspected neoplastic cells were detected with the indication of histological confirmation. Bone marrow aspirates were also obtained as a part of routine staging but no evidence of lymphoma was detected.

Histopathology: on histopathological skin samples, the epidermis appeared severely ulcerated and often replaced by abundant necrotic material; the dermis was diffusely infiltrated by a population of large lymphoid cells with a clear cytoplasm and an irregular nucleus often containing a voluminous nucleolus.

Mitoses were numerous and atypical among the cell population. These findings were suggestive of a nonepitheliotropic lymphoma (Fig. 4 a-c). PAS staining resulted negative (Fig. 4d). Via immunohistochemical analysis the cat was classified as having B-cell lymphoma (CD79a).

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All these findings were consistent with a final diagnosis of cutaneous B-cell lymphoma of the tarsus.

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Bacterial and fungal cultures: on tissue culture, bacteria of the genus Staphylococcus spp susceptible to several antibiotics were isolated whereas fungal culture was negative.

TREATMENT AND OUTCOME The cat was treated with corticosteroids alone. Nevertheless, a short-term progressive deterioration with further weight loss, persistent vomiting and local progressive disease occurred. The cat was finally euthanized after 15 days.

CONSIDERATION This clinical presentation can represent an intriguing condition for dermatologists who are not familiar with neoplastic diseases.

However, although the typical localization of this disorder could guide the clinician and to reach a correct diagnosis, a relatively short diagnostic approach becomes necessary, especially when early stages of the disease are faced. Nevertheless, this case may be misleading.

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Figure 3. Abdominal ultrasound and thorax radiography. Mesenteric lymphadenopathy (a) and diffuse broncho-interstitial disease (b).

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Figure 4. Dermatopathological findings. The dermis appears diffusely infiltrated by a population of large lymphoid cells (a) H&E, 20x; (b-c) H&E 40x.

PAS stainings are negative (d) 20x. Courtesy of Dr R.Bergottini â&#x20AC;&#x201C; IDEXX Italy.

The current World Health Organization (WHO) classification of lymphoma in humans describes a primary cutaneous diffuse large B-cell lymphoma with a predilection for legs. The disease predominantly affects elderly patients and, although causative related factors have not been found yet, it has been hypothesized that it may represent a lymphoproliferative response to antigenic stimuli in the skin. However, although various attempts have also been made in cats in order to find an explanation on tumor behaviour and tarsal location, any discernible correlation has not been found.

Sites of metastatic disease development including the associated or draining popliteal lymph node are confirmed at the time of diagnosis.

THE KEY ELEMENT OF THE CASE Localization, type of lesions and age of the cat; all these elements together can prompt a diagnosis of a neoplastic process.

A general objective examination that leads to lymph node sampling together with thorough staging is always encouraged.

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CASE 2. ALOPECIC, ULCERATED AND ERYTHEMATOUS PLAQUE ON THE TARSAL REGION IN A CAT

CUTANEOUS B-CELL LYMPHOMA OF THE TARSUS BRIEF DESCRIPTION OF THE DISEASE Lymphoma represents one of the most common lymphoproliferative disorders in cats although the cutaneous form has been very rarely reported.

Histologic evaluation may characterize cutaneous lymphoma as epitheliotropic (generally T-cell phenotype) or non-epitheliotropic (T- or B-cell phenotype). The clinical differentiation between these two forms can be extremely challenging. The lesions, consisting of focal to multifocal alopecia with scaling, non-healing ulcers, nodules or erythematous plaques which may mimic an eosinophilic plaque, are present in both epitheliotropic and non-epitheliotropic lymphomas. However, the cutaneous tarsal lymphoma in cats corresponds to an uncommon manifestation often described as a subcutaneous mass with a predilection for the tarsal region (Fig. 5) and in most of cases, this form is a non-epitheliotropic lymphoma, of high grade and of B-cell phenotype. This type of lymphoma appears to be an aggressive disease in cats with no current standard of care for the treatment.

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TREATMENT To date, the scarce number of cases reporting this disease limits an appropriate treatment. Actually, no case series have been published documenting response rates and/or survival times with a set treatment protocol. However, placental lysate, fibronectin, chemotherapy, corticosteroids alone, radiation therapy or surgery may be of some success and it is likely that a multimodality approach could be even more effective.

Figure 5. The cutaneous tarsal lymphoma in cats corresponds to an uncommon manifestation often described as a subcutaneous mass with a predilection for the tarsal region.

Feline eosinophilic granuloma complex (EGC) Feline eosinophilic granuloma complex (EGC) is a common finding in veterinary dermatology. It comprises a group of reaction patterns that affects the skin, oral cavity and mucocutaneous junctions of cats. It can resemble several other disease processes such as viral, bacterial or fungal infections. The commonly recognized lesions associated with EGC include eosinophilic plaque, eosinophilic granuloma and indolent ulcer (also referred to as eosinophilic or rodent ulcer). The eosinophilic granuloma produces a classical swollen lower lip or chin or a classical long, narrow lesion running down the back of the thigh (Fig. 6). All three lesion types share an inflammatory etiology and a pathogenesis involving an influx of eosinophils into dermal tissues. However, it may also manifest through a novel severe clinical presentation that does not fit into one of the aforementioned clinical entities, and it is represented by full-thickness ulcerations affecting both hocks and forelimbs.

It may be argued that the appearance of some lesions most closely resembles some cutaneous disorders rather than others. For this reason, dermatopathology may represent one important diagnostic test to be considered.

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