Molecular Heterogeneity of Canine Cutaneous Peripheral Nerve Sheath Tumors: A Drawback in the Diagnosis Refinement

Peripheral nerve sheath tumors (PNSTs) belong to a very heterogeneous group of neoplasms occurring both in dogs and humans. The aim of the present study was to evaluate the histological and immunohistochemical features of canine cutaneous PNSTs contributing to further refine their diagnosis.

The histopathological phenotype and biological behavior of 40 canine cutaneous PNSTs were evaluated and vimentin, S-100, glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE), desmin, alpha-smooth muscle actin (α-SMA) and Ki-67 immunoreactivity were assessed.

Respectively, 17 and 23 lesions were classified as benign and malignant PNSTs. The malignant lesions were more often positive for S-100 and presented a proliferation index significantly higher when compared to the benign ones (p<0.05).

The differential diagnosis of PNST on routine stained samples is difficult and the immunohistochemical examination may contribute to the final diagnosis. However, these lesions present a complex histogenesis and show very variable individual features; thus, an unequivocally immunohistochemical panel that could have supported the PNST diagnostic was not achieved. Nevertheless, we concluded that Ki-67 can be a useful marker helping to discriminate the biological behavior of canine PNST.