A 7-week-old boy with violaceous patches and skin nodules. Leukemia cutis

A 7-week-old boy presented to the pediatric dermatology clinic for evaluation of diffuse blue lesions on the skin. The mother first noticed a bluish lesion on the left thigh at 6 to 7 weeks of age. The child quickly developed several similar lesions and deeper nodules on the head, arms, and trunk. He had a history of ankyloglossia and subsequent uncomplicated repair, as well as a sister with neonatal anemia. He was otherwise well and thriving. Review of systems was unremarkable. His birth involved an uncomplicated delivery, with negative maternal serology. There was no history of maternal infection or recent exposure to infection. Physical exam revealed a well-appearing, non-dysmorphic, vigorous infant. Skin exam was notable for numerous dusky erythematous and violaceous-blue patches and nodules on the anterior scalp, bilateral arms, legs, face, and trunk - including the diaper area. Lesions ranged in size from 1 to 3 cm. The nodules were firm and non-tender. The remainder of his physical examination was normal without abnormal lymphadenopathy or hepatosplenomegaly noted. No mucosal lesions were noted. A biopsy was performed on a thigh lesion.