Histopathologic profile of alopecia areata in Indian patients

Alopecia Areata (AA) is a "non-scarring" alopecia that has an autoimmune basis. Though clinically distinctive, problems arise in diagnosis depending on the temporal stage of the disease at presentation; some of them progress to scarring alopecia and predicting its prognosis is difficult. Histological changes depend on the disease stage and site of the biopsy.

To describe the spectrum of histologic features in AA.

A prospective and retrospective study of H and E sections of all biopsies signed out as AA between 2001 and 2009 (20 cases) was undertaken.

The diagnosis was made on vertical sections in all cases. The total number of hair follicles ranged from 1 to 24 with an average of 7 and comprised mainly terminal follicles. Vellus follicles were scanty. Anagen to non-anagen ratio was 1:1.62. Miniaturization of follicles was noted in five (25%) cases. Peribulbar inflammation was seen in all the cases with a dominance of lymphocytes. Perifollicular fibrosis was noted in 12 (60%) and pigment casts in 5 (25%) cases. Scarring was seen in two cases. In these cases, a diagnosis of AA was rendered on the basis of even spacing of the fibrotic units and remnants of the catagenic basement membrane within the scars. The epidermis and interfollicular dermis were normal in all the cases.

The most consistent features of AA are an increase in non-anagen terminal follicles and peribulbar lymphocytic infiltrate. The etiology can be determined even in cases that have progressed to scarring.