K. Smith et al., CUTANEOUS EPITHELIOID SCHWANNOMAS - A RARE VARIANT OF A BENIGN PERIPHERAL-NERVE SHEATH TUMOR, Journal of cutaneous pathology, 25(1), 1998, pp. 50-55
Although benign epithelioid peripheral nerve sheath tumors have been d
escribed, they are rare, and benign epithelioid schwannomas have not y
et been established as a specific histologic variant. We present four
cases of tumors which we believe would meet criteria to be classified
as benign epithelioid schwannomas. Biopsy specimens obtained from four
different patients were examined with routine and immunohistochemical
staining. All the tumors were well-circumscribed lesions that were su
rrounded by a capsule containing EMA-positive cells. The cellular comp
onent was composed of epithelioid cells, in which there was a lack of
mitotic activity. Immunohistochemical studies showed the tumor cells w
ere S-100 protein and Leu 7 positive and HMB-45 negative. In addition,
type IV collagen encircled individual cells within the tumor, indicat
ing a continuous basal lamina. We report a group of cutaneous epitheli
oid schwannomas. Although the presence of such tumors is not unexpecte
d, this diagnosis may not be initially considered because of this rare
cytologic feature.