Acquired Localized Hypertrichosis

In 1978, a 2-year-old girl presented at Cook County Hospital in Chicago with a six-month history of new hair growth in areas that had been traumatized by multiple insect bites. The excessive hair growth, known as hypertrichosis, developed at the sites of postinflammatory changes resulting from the bites and the child's subsequent scratching. The hypertrichosis was characterized by multiple, hyperpigmented macules ranging from 1 to 2 cm with tufts of hair, and was distributed over the trunk, extremities, and to a lesser extent, the face, while sparing the interscapular and diaper areas. This case was unusual as it involved localized hypertrichosis acquired after inflammation and trauma from insect bites, and it was not observed in other family members.