The concept of transepidermal elimination (TE) was introduced by Mehregan1 in 1968. In this process, the epidermis shows changes of pseudoepitheliomatous hyperplasia and channels through which material from the dermis extrudes. The extruded matter frequently consists of material foreign to the dermis (as seen in calcinosis cutis or osteoma perforans), altered collagen (as seen in reactive perforating collagenosis, necrobiosis lipoidica, or granuloma annulare), or altered elastin (as occurring in pseudoxanthoma elasticum or elastosis perforans serpiginosa).2 The mechanism of TE is unknown.
We describe a patient who had perforating rheumatoid nodules (RNs) that histologically exhibited the features of TE. While we believe this phenomenon is not rare, we could find no similar cases reported in the literature.
Report of a Case
A 54-year-old woman was first seen in March 1981 for infection of a nodule on the anterior part of the shin. She had had a history of rheumatoid