Track

Clinical Studies

Abstract

Cutaneous myxoma is a rare entity that presents as a benign lobulated/multinodular lesion composed of bland spindle cells in myxoid stroma. Cutaneous myxomas may be associated with Carney complex with myxomas of the external auditory canal, although relatively rare, being highly associated. Ber-EP4 and MOC-31 are antibodies to EPCAM (epithelial cell adhesion molecule). Ber-EP4 is a highly sensitive and specific stain for basal cell carcinoma. MOC-31 targets a different epitope on the surface of EPCAM and has recently garnered some attention as a sensitive stain for the identification of basal cell carcinoma. Herein we report a potential pitfall with the use of MOC-31 IHC for suspected basal cell carcinoma in the case of a superficial biopsy of an ear canal lesion. Histologic examination of additional sections revealed a cutaneous myxoma with follicular induction and positive MOC-31 staining. This case prompted an EMR search identifying 9 cases of cutaneous myxoma from auricular and non-auricular sites. Four cases exhibited superficial follicular induction and all were from the ear canal. The remaining five cases did not exhibit follicular induction and were from extra-auricular locations. Three of the auricular cutaneous myxomas were excised and the follicular induction within the context of cutaneous myxoma was readily identified. In the case of the superficial biopsy, the positive staining of MOC-31 was a confounder and other morphologic findings  as well as clinicopathologic correlation allowed for the accurate diagnosis. We present follicular induction as a potential pitfall in cutaneous myxomas, particularly those of the ear canal.