Isotretinoin treatment of 12 dogs with epitheliotropic lymphoma

BACKGROUND

Epitheliotropic lymphoma is an uncommon cutaneous malignancy of T lymphocytes. Limited information is available regarding the treatment and outcome of dogs with this disease.

OBJECTIVES

To evaluate the treatment outcome and toxicity profile of isotretinoin in dogs with epitheliotropic lymphoma.

ANIMALS

Twelve dogs with a diagnosis of epitheliotropic lymphoma were included.

MATERIALS AND METHODS

A medical database was searched for dogs diagnosed with epitheliotropic lymphoma and treated with isotretinoin between 2010 and 2021. Diagnosis, treatment details and tumour response were recorded for 12 dogs.

RESULTS

All lesions resolved in four of 12 (33%) treated dogs. Lesions visibly improved in a further three dogs, giving a response rate of 58%. Two dogs' lesions remained unchanged and three progressed despite therapy. Adverse effects occurred in three dogs (25%), all of which were rapidly resolving or not affecting quality of life.

CONCLUSION

Isotretinoin treatment was a well-tolerated and effective treatment for canine epitheliotropic lymphoma.

A retrospective study comparing histopathological and immunopathological features of nasal planum dermatitis in 20 dogs with discoid lupus erythematosus or leishmaniosis

BACKGROUND

In areas endemic for leishmaniosis, discoid lupus erythematosus (DLE) and canine leishmaniosis (CanL) are the most common differential diagnoses for nasal planum erosive-ulcerative dermatitis in dogs.

HYPOTHESIS/OBJECTIVE

To compare histopathological and immunopathological features of canine nasal planum erosive-ulcerative dermatitis with depigmentation due to DLE or CanL.

ANIMALS

Nasal planum biopsies from dogs with nasal planum loss of architecture, depigmentation, swelling, erosions or ulcerations due to DLE (n = 14) or CanL (n = 6).

METHODS

Sections of paraffin-embedded samples, stained with haematoxylin and eosin were reviewed. Samples were examined using antibodies targeting T cells (CD3), B cells (CD20), macrophages (Mac387) and class II major histocompatibility complex (MHC II). Histopathological and immunophenotypical findings were compared between DLE and CanL cases.

RESULTS

Lichenoid and interface dermatitis were observed in both DLE and CanL cases. A nodular-to-diffuse, superficial and/or deep dermatitis with macrophages, lymphocytes and plasma cells was present only in CanL samples. CD20-positive cells predominated over CD3- and Mac387-positive cells in the two conditions. The percentage of dermal Mac387-positive cells was higher in CanL compared to DLE samples and the difference was statistically significant (P = 0.025).

CONCLUSIONS/CLINICAL IMPORTANCE

In this study, similar histopathological and immunopathological findings were observed in dogs with nasal planum lesions due to DLE or CanL. Therefore, in areas endemic for leishmaniosis, the presence of the parasite should be investigated in canine nasal planum dermatitis showing clinical and histopathological features suggestive of DLE.

Epitheliotropic T-cell lymphoma in a guinea pig

A 4-year-old female guinea pig was presented with pruritic, erythematous, hypotrichotic and scaling skin lesions, mainly involving the abdomen and the hindlegs. Clinical abnormalities were limited to the skin, and the guinea pig was otherwise healthy. The dermatological diagnostic work-up excluded ectoparasites, dermatophytosis and an endocrinopathy as differential diagnoses for the pruritus and hair loss. An allergic dermatitis was under investigation when the general and skin condition deteriorated. A neoplastic skin disorder was suspected, and skin biopsies revealed changes consistent with a cutaneous epitheliotropic T-cell lymphoma. Pautrier's microabscesses and immunophenotyped CD3(+) CD79(-) lymphocytes were identified. Owing to the deteriorating condition of the animal and the unknown but most likely poor prognosis of this disease, the guinea pig was euthanized. To the authors' knowledge, this is the first case report of cutaneous epitheliotropic T-cell lymphoma in the guinea pig with characteristic histopathological and immunohistochemical features.