Langerhans cell histiocytosis presenting as blueberry muffin baby.

Blueberry muffin baby is a descriptive term for purpuric lesions reflective of extramedullary hematopoeisis. The clinical lesions most commonly result from intrauterine infections, such as rubella and cytomegalovirus, and less commonly with malignancy and hematologic disorders. Langerhans cell histiocytosis is a clonal proliferation of dendritic histiocytes in the skin. This has very rarely been associated with a blueberry muffin presentation. We report the case of a newborn with typical lesions of cutaneous hematopoiesis and lytic bone lesions related to Langerhans cell histiocytosis. At birth, approximately 40 2 mm to 5 mm purpuric, nonblanching macules were scattered on the trunk, extremities, and soles of our patient. Laboratory studies were unremarkable and cultures were negative. Skin biopsy showed a dermal proliferation of histiocytes staining positive for S100 and Cd1a. Pediatric bone surveys, chest radiographs, and computed tomography scans of the head were normal. Six months later, the skin lesions had resolved, but radiographs revealed lytic bone lesions of the right tibia, right ilium, and left pubic ramus, consistent with skeletal Langerhans cell histiocytosis.