Epidermal psoriasiform hyperplasia, an unrecognized sign of folliculitis decalvans: a histological study of 26 patients

Abstract

Background

Follicular hyperkeratosis along with hyperplasia of the follicular and inter-follicular epithelia are major histopathological characteristics of Hidradenitis Suppurativa (HS). The presence of an occasional thickening of lesional skin in some Folliculitis Decalvans (FD) patients and histological similarities between FD and HS led us to look for epidermal hyperplasia and follicular hyperkeratosis in FD patients.

Patients and method

We performed a retrospective histological analysis of 26 patients with FD.

Objective

We sought to find out whether the presence of hyperplasia of the inter-follicular epidermis and of the follicular epithelia could be verified in FD, with reference to the work of Von Laffert et al. concerning HS.

Results

The main quantitative and qualitative data were: follicular hyperkeratosis (77%), hyperplasia of the inter-follicular epidermis (92%) with a psoriasiform aspect (88%), atrophy of the follicular epithelia (85%), plasma cells in infiltrate (92%) in large quantities (42%), follicular microcysts (60%), atrophy of the sebaceous glands (85%), polytrichia (54%).

Conclusion

Epidermal hyperplasia, sometimes psoriasiform, and follicular microcysts, are significant histological signs of FD, which have been ignored until now although they seem very common.

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