Aspectos epidemiológicos, anatomopatológicos e moleculares dos linfomas cutâneos em cães

Abstract

Cutaneous lymphomas are uncommon tumors in dogs that can occur as epitheliotropic and non-epitheliotropic types. The epitheliotropic type comprises three distinct clinicopathological presentations already well established. However, the non-epitheliotropic lymphoma, despite has been recognized is poorly characterized, representing a heterogeneous group of presentations not yet correlated and that apparently can mimic different skin tumors, configuring a diagnostic challenge. Therefore, this study aimed mainly establish whether there is a correlation between the macroscopic presentation and the histological subtypes of cutaneous non-epitheliotropic lymphoma in the population of dogs under study. Additionally, aimed to determine the prevalence of each type and histological subtype of canine cutaneous lymphoma, and describe the epidemiological and anatomopathological characteristics of the cases. From a total of 38 cases of cutaneous lymphoma diagnosed in dogs, 17 (44,7%) cases were considered as epitheliotropic and 21 (55,3%) cases as non-epitheliotropic. From 17 cases of cutaneous epitheliotropic lymphoma, 13 (34,2%) were subclassified as mycosis fungoides, and four (10,5%) as pagetoid reticulosis. The cases of cutaneous non-epitheliotropic lymphoma included: anaplastic large T-cell lymphoma (ALTCL [9/21 {23,9%}]), peripheral T-cell lymphoma, unspecified (PTCL-NOS [4/21 {10,5%}]), subcutaneous panniculitis-like T-cell lymphoma (SPTCL [4/21 {10,5%}]), diffuse large B-cell lymphoma – immunoblastic type (DLBCL [2/21 {5,2%}]), lymphomatoid granulomatosis (LYG [1/21 {2,6%}]), and marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) – lymphoplasmacytic variant (1/21 [2,6%]). Based on the anatomopathological findings, it was possible to infer that when faced with multiple, nodular or placoid skin lesions, predominantly on the trunk and limbs, the diagnosis is more likely to be consistent with ALTCL. Whereas, with solitary skin nodules or plaques, PTCL-NOS will be the most frequently seen histological type. When these lesions are exclusively located in the subcutaneous tissue, one should first think about SPTCL and, more rarely, DLBCL. Regarding to epitheliotropic cutaneous lymphomas, the cutaneous form of mycosis fungoides is the most commonly observed in dogs, especially in the pre-mycotic and mycotic phases. We hope that this information can assist veterinary clinicians and pathologists in their diagnostic routines, and contribute to the characterization of non-epitheliotropic cutaneous lymphomas in the canine species.