B. Infantile myofibromatosis

A newborn girlwith a nodular lesion on the scalp present since birth was seen at the der-matology clinic. The parents reported occasional erosions and crusting that resolved with topical mupirocin, 2%, cream, butwith no continued growth. Themother had had a normal pregnancy. Physical examination revealed a firm, exophytic, and flat-topped nodule, with superficial erosion and crust on the right parietal side of the scalp measuring 3 cm in diam-eter and 1 cm thick (Figure, A). No other skin lesions were found. A 4-mm punch skin biopsy was performed, and tissue was sent for pathologic analysis (Figure, B and C). Cere-bral and abdominal ultrasonography revealed no evidence of visceral involvement. The lesion regressed without treatment over a period of 8 months. Close follow-up every 3 months was scheduled, and complete involution of the tumor was noted at 10 months of age (Figure, D). A