2021 Volume 60 Issue 6 Pages 359-364
Background : Epithelioid schwannoma is a peculiar histological subtype of schwannoma, and its occurrence in the salivary gland is extremely rare. Herein, we report a case of epithelioid schwannoma arising from the parotid gland.
Case : A 50-year-old man presented with a 1-year history of a left parotid gland swelling. Pleomorphic adenoma and myoepithelial tumors were suspected from the findings of fine-needle aspiration cytology (FNAC) of the lesion. Therefore, a left superficial parotidectomy was performed, and imprint cytology of the operated specimen revealed tumor cells with round- to spindle-shaped nuclei containing fine-granular chromatin and small, but conspicuous nucleoli, and clear-to-granular cytoplasm, forming syncytial cell clusters. Histologically, the well-defined tumor was composed of round- to spindle-shaped cells scattered in isolation, in small nests, or in cord-like or sheet-like arrangement, within a myxomatous and fibrous stroma. No necrosis or mitoses were evident. Immunohistochemically, tumor cells showed positive staining for S-100 protein, but negative staining for epithelial and myoepithelial markers. The Ki-67 labeling index was less than 1%. Finally, the tumor was diagnosed as an epithelioid schwannoma.
Conclusion : When syncytial cell clusters consisting of bland round to spindle-shaped cells are observed in FNAC of salivary gland tumors, the possibility of epithelioid schwannoma should be borne in mind in the differential diagnosis.
