A 27-year-old white male medical student presented with a 1-month history of patches of hair loss on his right shin. There were no similar lesions elsewhere on his body. He denied trauma or any application of topical agents, and in general he felt well.
According to his medical history, he had allergic rhinitis and urticaria as a child. There is a family history of atopy; his mother has asthma; and his sister and brother have allergic rhinitis.
On physical examination, 3 large patches of hair loss with visible black dots and broken-off hairs were observed on the right upper anterior shin area (Figure 1). The skin in these areas felt like sandpaper on palpation. There were no exclamation point hairs. The rest of the skin, nails, and hair were normal. There was no lymphadenopathy, and examination of his heart, lungs, and abdomen revealed no abnormalities. A punch biopsy specimen was obtained from the site of alopecia and was stained with hematoxylin-eosin (Figure 2 and Figure 3).