Infantile myofibromatosis: a cause of severe bone pain in a neonate.

A 3-week-old, female infant, developed severe bilateral shoulder pain in association with large, symmetrical, lytic lesions in the proximal humeri. The radiological appearance was suggestive of infantile myofibromatosis and bone biopsy confirmed the diagnosis. She subsequently made a complete recovery. This uncommon condition is infrequently confined to bone and except in the presence of obvious pathological fracture, severe pain has not previously been reported.