TUMOR MALIGNO DE NERVO PERIFÉRICO (SCHUWANNOMA MALIGNO) DIAFRAGMÁTICO EM CÃO POODLE – RELATO DE CASO

Abstract

Peripheral nerve sheath tumor is the term that has been proposed to include schwannomas, neurofibromas (nerve fiber tumors) and neurofibrosarcomas (malignant nerve fiber tumors). The diaphragm represents an unusual location for neoplasia in both domestic animals and human beings. This report describes a malignant schwannoma in the diaphragm of a 13-year-old Poodle dog. Multiple nodules were seen to be distributed throughout of the diaphragm and abdominal cavity of the animal. The mediastinal lymph nodes were replaced by a large solitary tumorous mass. Histologically, diaphragmatic tumour and metastasis were composed of pleomorphic, large spindle cells exhibiting lightly eosinophilic cytoplasm, indistinct cell borders, and large fusiform nuclei with prominent nucleoli. The neoplastic cells are arranged in interwoven fascicles and bundles with sparse collagenous stroma. The diaphragm is an unusual site of occurrence of cancer in companion pets and humans. The phrenic nerve was possibly the site of origin of the tumor in our case.