Tumor maligno de bainha de nervo periférico mamário em cadela: Relato de caso

Abstract

Peripheral nerve sheath tumors correspond to a group of neoplasms in the nervous system, which include neurofibromas, schwannomas and perineuromas, but which, for simplification, are grouped in this way, differentiating between benign and malignant forms. The breast region is little affected by this type of neoplasm. This paper describes the clinical, hospital, imaging and histological aspects of a recurrent and metastatic malignant peripheral nerve sheath tumor in the abdominal region of a 6-year-old female Labrador retriever. The animal had a large increase in ulcerated volume in the inguinal breast region, in addition to a similar, but smaller, lesion in the left pelvic limb. Ultrasonographically, the mass appeared as a nodular structure with a defined capsule, mixed echogenicity and heterogeneous echotexture, with the presence of a cystic structure with anechoic content, suggesting that it was a neoplastic process. On the second chest x-ray examination, the lung fields were diffusely opacified with multiple soft tissue radiopaque structures inside, signs suggestive of lung metastasis. Such findings in association with the clinical picture corroborated the decision for the euthanasia procedure. Histologically, a mantle of fusiform cells arranged in multidirectional bundles, moderate to reduced and vacuolated cytoplasm, moderate to severe anisokaryosis is observed. Malignant tumors of the peripheral nerve sheath (NPMT) are rare in companion animals, and reports of this neoplasm involving mammary tissue are also scarce. In this report, NPMT associated with lung metastasis was diagnosed, with skin and mammary gland innervation as the most anterior site of origin.