Diffuse bronchioloalveolar carcinoma in a dog: clinicopathological and immunohistochemical findings/Carcinoma bronquiolo-alveolar difuso em um cao: aspectos clinico-patologicos e imuno-histoquimicos

A 12-year-old poodle dog was presented with a history of severe dyspnea. Radiology revealed diffuse pulmonary lesion which was diagnosed as interstitial pneumonia. At necropsy there were multiple small coalescent nodules distributed throughout the lung parenchyma. Histologically the nodules consisted of cubic to low columnar atypical epithelial cells which were PAS-negatives. In the immunohistochemistry reaction this cells were marked for cytokeratin, TTF (thyroid transcription factor)-1 and surfactant apoprotein A (SP-A). The neoplastic cells were negative for vimentin and cromagranine A. The necrotic areas were not marked for TTF-1 and SP-A. Based of the histopathological and immunohistochemistry findings a diagnosis of non-mucinous bronchioloalveolar carcinoma with diffuse involvement of the lung was made. This is a rare form of presentation for this tumor, and it can mimetize pneumonia on clinical and morphological examination. A definitive diagnosis for this condition should be based on histopathology and immunohistochemistry. Key words: immunohistochemistry, neoplasm, lung, cancer, pathology. Um cao Poodle, 12 anos de idade, demonstrou marcada dispneia. Na radiografia, havia comprometimento difuso do pulmao e foi feito diagnostico de pneumonia intersticial. Na necropsia, o pulmao continha multiplos e pequenos nodulos coalescentes. Histologicamente, os nodulos eram compostos por celulas epiteliais cuboides ou colunares baixas atipicas, que eram PAS-negativa. A avaliacao imunohistoquimica revelou positividade para citoceratina, fator 1 de transcricao da tireoide (TTF-1) e apoproteina A surfactante (SP-A). O tumor foi negativo para vimentina e cromogranina A. As areas necroticas nao marcaram para TTF-1 e SP-A. Com base nos achados histopatologicos e imuno-histoquimicos, foi realizado o diagnostico de carcinoma bronquiolo-alveolar nao mucinoso com envolvimento difuso do pulmao. Essa e uma forma rara de apresentacao desse tumor que pode mimetizar pneumonia na avaliacao clinica e radiografica. O diagnostico definitivo e baseado na histopatologia e imunohistoquimica. Palavras-chave: imuno-histoquimica, neoplasma, pulmao, cancer, patologia.