Indolent cutaneous T‐cell lymphoma presenting as cutaneous lymphocytosis in dogs

Abstract

Cutaneous lymphoproliferative diseases encompass a spectrum of lesions, ranging from self-limiting, reactive infiltrates to high-grade lymphomas. In humans, cutaneous lymphocytosis (CL) refers to self-limiting or slowly progressive monomorphic lymphocytic infiltrates of mostly unknown cause. It morphologically mimics cutaneous lymphoma. CL in cats also is a slowly progressive disease. Immunophenotyping and clonality testing of feline CL support an indolent lymphoma for the majority of cases studied. This study reports CL in dogs. Erythematous, scaly and alopecic macules, patches or plaques were present in eight dogs. Breed predilection was not observed; six of eight dogs were females; and ages ranged from 5 to 14 years. Diffuse monomorphic non-epitheliotropic infiltrates of CD3(+) (eight of eight), CD45(-) (four of eight) or CD45(+/-) (four of eight) and CD45RA(-) (seven of eight) T lymphocytes were present in the superficial and mid-dermis. Further immunophenotyping of five cases revealed TCR-gammadelta(+) T cells (one of five) or TCR-alphabeta(+) (four of five) T cells. TCR-alphabeta(+) populations were either CD8(+) (two of four) or CD4(-)CD8(-) (2/4). Clonality testing found clonal (seven of eight) or pseudoclonal (one of eight) rearrangement of the TCR-gamma locus of the lesional T cells. Prednisone, prednisolone and methylprednisolone acetate were the most commonly administered drugs. The lesions remained stable for long periods up to 6 years. Five dogs were euthanized due to progression of the skin lesions (three of five), peripheral lymphadenopathy of unknown origin (one of five) or high-grade lymphoma (one of five). One dog was lost for follow-up and two dogs are still alive (17 and 9 months after diagnosis). Canine CL is best considered an initially indolent lymphoma, with slow progression and a potential for progression to high-grade lymphoma.

Cytologic and immunocytochemical characterization of feline progressive histiocytosis

“…Xanthomas were excluded based on the absence of cytoplasmic cholesterol crystals, erythrophagocytosis, and abundant cytoplasmic vacuolation of histiocytes . Lesions in cutaneous lymphocytosis yield a striking predominance of small mature lymphocytes . Poorly differentiated mast cell tumors can resemble histiocytes, but cytologic examination usually reveals some cytoplasmic metachromatic granules even in poorly granulated tumors.…”

Erythema multiforme and epitheliotropic T‐cell lymphoma in the oral cavity of dogs: 1989 to 2009

“…Polymerase chain reaction (PCR) products were visualised on a UV transilluminator and photographed. Additionally, triplicate samples were evaluated by capillary gel electrophoresis using e‐Gene HDA‐GT12 (QIAxcel System by Qiagen) and the QIAxcel DNA High Resolution Kit 1200 (Qiagen) per kit instructions (Affolter and others ). Samples (10 μL) were loaded into 0·2‐mL 12‐tube strips and placed into the e‐Gene HDA‐GT12.…”

Dermatopathology – the link between ancillary techniques and clinical lesions

“…The use of antibodies in diagnostic pathology has become an indispensable technique that is routinely used by many diagnostic laboratories and pathologists . Pathologists often have to rely on the immunophenotype of a neoplastic cell population to identify its origin . However, antibodies are specific for an antigen in a specific species.…”