Histopathological changes in different stages of alopecia areata.

Alopecia areata is a common disorder affecting any of the hair bearing areas of the body. Most of the cases are diagnosed on the clinical ground only. Histopathological changes may help in the diagnosis in difficult cases. The present study was designed to observe the histopathologic changes of alopecia areata at different stages. Thirty consecutive patients suffering from alopecia areata were enrolled. Face to face interview was performed using a structured pre-tested questionnaire. At the initial visit, one 4mm punch scalp biopsy specimen was taken from an area of hair loss. Biopsy specimens were sent in a test tube filled with formalin to the department of Pathology, Bangabandhu Sheikh Mujib Medical University (BSMMU) where tissue was processed, sectioned and slides were prepared. Haematoxylin and eosin stains were used. Aanagen hairs were decreased in all stages of alopecia areata. Telogen hairs increased in acute and chronic stages whereas catagen hairs increased markedly in sub-acute stage. Although miniaturized (atrophic) follicle was frequently found in chronic stage. It was absent in acute and sub-acute stages. Moderate to dense peribulbar infiltration of lymphocytes were observed in acute stage and mild to moderate infiltration in sub-acute stage. In chronic stage either no or mild infiltrations were observed. Peribulbar infiltration of eosinophils and macrophages were seen in all stages of alopecia areata. Alopecia areata can be diagnosed with some confidence, even when inflammatory infiltrate is absent, based on increased numbers of telogen hairs in the acute and chronic stages, increased miniaturized hairs in chronic stage and markedly increased catagen hairs in sub-acute stage.