Avaliação histopatológica e imuno-histoquímica da pele de cães (Canis familiaris, Linnaeus, 1758) com infecção natural por Leishmania infantum (Nicolle, 1908)

Abstract

Canine visceral leishmaniasis is a systemic disease caused by Leishmania infantum. Dog usually present a variable clinical signs include anorexia, weight loss, generalized lymphadenopathy, but the skin lesion are the most found. The goal of this study was to evaluate the histophatological changes and detect amastigotes forms by immunohistochemistry in skin from dogs with natural infection by L. infantum. Fragments of ulcerated and normal skin from 22 positive dogs were collected, fixed in formalin and processed for histopathology and immunohistochemistry. Two groups of animals were used: the first was composed by 12 dogs with positive ELISA test and bone marrow biopsy (Group 1) and the second composed by 10 dogs positive only by ELISA test (Group 2). The results of immunohistochemistry showed amastigotes forms in 91,67% (11/12) of animals from Group 1, while none (0/10) of dogs in Group 2 was positive in the same technique. Regarding the histopathological pattern of intact skin, were observed nodular, perifolicular, diffuse and interface dermatitis in 9,1% (1/11) each one, lichenoid dermatitis in 27,3% (3/11), periadnexial dermatitis in 18,2% (2/11) and mixed dermatitis (nodular and perifolicular) were observed in 9,1% (1/11) of the dogs. Histological evaluation showed granulomatous cellular infiltration composed of macrophages, lymphocytes, plasma cells in 90,9% (10/11), while 9,1% (1/11) of health skin did not show changes. On the other hand, the histopathological pattern of ulcerative skin revealed perifolicular and periadnexial dermatitis in 9,1% (1/11) each one; lichenoid dermatitis in 18,2% (2/11), diffuse dermatitis in 27,3% (3/11) and 36,4% (4/11) of mixed dermatitis (interface and deep perivascular; intersticial and periadnexial; interface and periadnexial; interstitial, superficial perivascular and periadnexial). Histological evaluation of ulcerative skin showed granulomatous cellular infiltration composed of macrophages, lymphocytes, plasma cells in 81,8% (9/11) and piogranulomatous cellular infiltration composed of macrophages, lymphocytes, plasma cells and neutrophils in 18,2% (2/11) of animals. In conclusion, amastigotes forms of L. infantum were demonstrated using the technique of immunohistochemistry in ulcerated and intact skin of dogs parasitologically positive and the histological patterns of ulcerated skin revealed mainly mixed dermatitis characterized by granulomatous cellular infiltration, while the intact skin demonstrated lichenoid dermatitis by the same inflammatory infiltrade.