Histopathology of Alopecia Areata, Acute and Chronic: Why Is It Important to the Clinician?

The document highlighted the significance of recognizing the histological stages of alopecia areata (AA) for proper diagnosis and treatment. AA, a T cell-mediated autoimmune disease, shows a peribulbar lymphocytic infiltrate in the acute stage, which may be absent in later stages. The disease has acute, subacute, chronic, and recovery phases, with histological changes including variations in terminal catagen and telogen hairs and an increase in miniaturized hairs. Horizontal sectioning of scalp biopsies is recommended for diagnosing AA, particularly when typical histological signs are missing, as it allows for the evaluation of hair follicle density and hair cycle stages. The document also mentions the discovery of the AA gene and the potential role of the arrector pili muscle and bulge in reversing follicular miniaturization, which could lead to new treatments. Accurate diagnosis is essential for both the physician and patient.