Cutaneous epitheliotropic T-cell lymphoma in a dog: Clinical responses to lomustine and gemcitabine

Abstract

A 5-year-old, spayed female Maltese dog presented with generalized multifocal pruritic erythema and alopecia for a month. Initial skin biopsy suggested cutaneious histiocytosis. The dog had been treated with the immunosuppressive therapy for a month, but multifocal erythematous patches and plaques were newly observed. Direct imprint smear of cutaneous lesions suggested a lymphoma and rebiopsy was performed. Microscopic examination demonstrated a round cell tumor with epitheliotrophism to the epidermis and adnexal structures. The neoplastic round cells were strongly positive for CD3 yet negative for CD79a, indicting the tumor was cutaneous epitheliotropic Tcell lymphoma. After 2 cycles of oral administration of lomustine (70 mg/m2, once every 2-3 weeks), only partial response was observed. Alternative chemotherapy with gemcitabine (500 mg/m2, 30-minute IV infusion, once every week) was initiated. A total 3 cycles of gemcitabine failed to control the progression of disease, and the dog was euthanized on Day 69 after the 1st lomustine treatment.