Degenerative ("ancient") changes in benign cutaneous schwannoma. A light microscopic, histochemical and immunohistochemical study.

We studied the degenerative "ancient" changes in 19 cases of benign cutaneous schwannoma (BCS). Using conventional and immunohistochemical stains, we found (a) degenerative changes in 15 of 19 BCS; (b) prominent vascular abnormalities in 11 of 15 BCS; and (c) cytologic atypia in 15 of 19 BCS, without mitotic figures. We concluded that (1) degenerative, i.e., "ancient" changes are common in BCS and are qualitatively similar to those described in cellular schwannoma; (2) vascular abnormalities may be related to these degenerative changes; (3) cytologic atypia is commonly associated with "ancient" changes in BCS, but BCS is less cellular and has few if any mitotic figures as opposed to cellular schwannomas; and (4) the changes in "ancient" schwannoma do not indicate a "cellular" schwannoma.