Lichen planus: histologic involvement of an epidermoid cyst

Only little is known about the involvement of the epithelium of epidermoid cysts in dermatoses with keratinocytic changes because these cysts are excised only rarely. Histological findings on an epidermoid cyst, excised from a patient with wide-spread lichen planus are reported. These changes exactly agree with the epidermal histological features of lichen planus and cannot be interpreted as a foreign body reaction.