Eruptive infundibulomas. A distinctive presentation of the tumor of follicular infundibulum.

Hundreds of asymptomatic pale erythematous lesions, 2 to 15 mm in diameter, with complex angulated shapes in a mantle distribution over the upper portion of the chest and back and the shoulders, developed in two unrelated young men. Actinic porokeratosis, discoid lupus erythematosus, pityriasis versicolor, and acne scars were considered as possible diagnoses, but none of these appeared appropriate. Multiple skin biopsy specimens from both patients showed tumors of follicular infundibulum (infundibulomas), benign platelike proliferations of the external root sheath that were outlined by a prominent brushlike elastic network. This presentation of the tumor of follicular infundibulum can be recognized by its unusual clinical pattern and histopathology.