Large Plantar Mass in a Newborn

Abstract

A 1-day-old white boy was seen by the dermatology service for a congenital mass on the plantar surface of his left foot. The mass appeared to be slightly tender. There had been no episodes of bleeding. The infant was born at term, and there were no complications during pregnancy or delivery. He was otherwise healthy and taking no medications.On physical examination, he had a 3.5 × 5 cm, slightly firm, violaceous tumor on the medial plantar surface of his left foot extending between the first and second toes. A 0.5-cm crusted erosion over the first metatarsal head was also seen. The periphery of the tumor had a grayish hue and was softer with a lax, convoluted appearance ( Fig. 1). The infant withdrew his foot upon palpation of the mass. No other lesions were noted.Ultrasound showed a solid, superficial mass with no appreciable blood flow. Plain radiographs of the left foot revealed a soft tissue mass with small areas of mineralization. Forefoot adductus and a shortened second metatarsal were also noted on radiograph. Magnetic resonance imaging (MRI) showed a soft tissue mass on the plantar surface of the left foot extending into the deeper tissues between the first and second digits. There was diffuse enhancement of the lesion following gadolinium administration.A 4-mm punch biopsy specimen was obtained. The hematoxylin-eosin-stained specimen showed a spindle cell proliferation with abundant small, narrow, mildly branching vascular channels extending into the deep dermis ( Fig. 2A,B). Mitotic figures were present (0-2 per 10 high power fields), but no cytologic atypia was identified. Immunohistochemistry stains were positive for vimentin and smooth muscle actin, but negative for desmin and S-100. CD31 was positive in endothelium lining the vasculature. WHAT IS YOUR DIAGNOSIS?Solitary congenital (infantile) hemangiopericytoma. Figure 1. Large violaceous tumor on the plantar surface of the left foot at day 1 of life.