Tumor misto de glândula sudorípara canina / Canine sweat gland mixed tumor

ABSTRACT

Background: Sweat gland mixed tumors (SGMT) are considered a rare neoplasm in dogs. This tumor present clinically as nodules large, well defined and looks similar to other skin tumors. The diagnosis of cancer is based on aspiration cytology and histopathology. Due to the rarity of the tumor, absence of appropriate criteria for analysis and divergence in the diagnosis, identification and characterization of the SGMT can be considered a challenge for veterinary medicine. Thus, it becomes necessary to adopt standardized criteria for the diagnosis and understanding of the biological behavior of these tumors. This paper aims to describe the characteristics of a histomorphological and immunophenotypic SGMT canine. Case Microscopic examination showed a measuring 6,8x11,0x6,4cm surface, with subcutaneous mass with fi rm consistency, solid look and ulcerated. Presented to the court rangência containing well-defined multilobulated mass of soft consistency, solid look, color usually brownish with whitish spots. In some lobes the content presented was friable. On microscopic examination showed proliferation of epithelial cells forming glands or clefts lined by cubical epithelium and mesenchymal component characterized by a proliferation of spindle cells, which sometimes had starring appearance. In addition, there was also formation of cartilage and bone necrosis and mixed infl ammatory infi ltrate discreet. The immunohistochemical analysis revealed intense and diffuse cytoplasmic staining (++) for CK AE1/AE3 antibody in ductal epithelial cells, reactivity for p63 in myoepithelial cells and periductal myoepithelial cells of weak in myxoid matrix. The cell proliferation rate was low. Histopathology demonstrated a tumor mass composed by an epithelial component with glandular formation lined by cuboidal epithelium and a mesenchymal component characterized by a spindle cell proliferation. Cells with a stellate appearance, cartilage and bone formation, necrosis and mild mixed inflammatorry infiltrate were also observed. Discussion: The SGMT is a rare neoplasm in dogs. These tumors usually present myoepithelial proliferation with formation of chondroid metaplasia, and in some cases, osteoid. Usually, a set of molecular changes at different levels of cell regulation is responsible for the formation of tumors. Cancers of the skin appendages comprise a broad spectrum of benign and malignant tumors that exhibit morphological differentiation. Studies using immunohistochemical markers for components of the cytoskeleton are extremely useful in the diagnosis of these neoplasms. In evaluating the expression of cytokeratin AE1/AE3 positivity was observed cytoplasmic components of ductal epithelial apocrine glands. The expression of p63 for myoepithelial cells in the periductal areas was observed in this study demonstrating preservation of the basal layer, thus confi rming the benign nature of the neoplasm. Furthermore, immunostaining for the protein helped disclosure of myoepithelial cells forming the myxoid matrix. The evaluation of proliferative activity of SGMT for Ki67 proved to be weak. Low proliferative index are related to well-differentiated cancer cells and better prognosis in these cases. Before we confi rmed the histomorphological diagnosis of mixed tumor of sweat gland. Immunohistochemical markers such as CK AE1/AE3, p63 and Ki67 may aid in the diagnosis of cancer, helping in understanding the biological behavior of this tumor.(AU)