Malignant peripheral nerve sheath tumor in a cat: cytological, histopathological, and immunohistochemical aspects

The malignant peripheral nerve sheath tumor is an uncommon tumor in cats. Cytological preparations can be used to diagnose such neoplasia, being a useful tool to characterize a spindle cell tumor presenting several criteria of malignancy. Histopathological examination is required for a definitive diagnosis, complemented by immunohistochemical techniques. This paper describes a case of malignant peripheral nerve sheath tumor in a cat. The diagnosis of mesenchymal neoplasm with high pleomorphism was suggested by cytology, performed through fine needle aspiration. Thereafter, the nodule underwent surgical excision, histopathological analysis, and immunohistochemistry. For immunohistochemical analysis, the panel included vimentin, S-100 protein, GFAP, von Willebrand factor, and cytokeratin. The markers that showed positive immunolabeling were vimentin and S-100 protein, confirming the mesenchymal origin of the tumor. It is possible to conclude that cytology was useful and reliable to pre-diagnose the neoplasm in this case. Added to the convenience and short time for execution of the technique, the aspiration cytology is recommended to suggest a diagnosis in similar cases and support the clinical management of the patient.