Infantile myofibromatosis: a cause of vertebra plana.

A 6-week-old boy was seen in the emergency department with progressive enlargement of head and neck masses. Bilateral periauricular masses had been present since birth and had undergone recent cervical extension. A mass of the right nasolabial fold had been present since 3 weeks of age. The lesions were asymptomatic and the infant was otherwise well. Computed tomography (CT) of the head and neck showed multiple partially calcified masses (Fig 1A and B) that were similar in attenuation to muscle and demonstrated peripheral enhancement after intravenous administration of contrast material. Additional calvarial and metadiaphyseal lytic long-bone lesions were demonstrated on skeletal survey. Some bone lesions had thin zones of marginal sclerosis, whereas margins on others were poorly defined. CT of the chest and abdomen showed no evidence of visceral involvement. Surgical biopsy of one of the neck masses yielded the diagnosis of infantile myofibromatosis. The patient did well without additional treatment after discharge. Physical examination, plain radiography, and CT examination showed interval enlargement of some masses and diminution of others over the next 5 months. Follow-up skeletal survey at 6 months of age showed enlargement of all of the bone lesions. Features included better defined sclerotic margins, cortical thinning, and bone expansion. A new lesion was present involving the L-5 vertebral body. A lateral radiograph and magnetic resonance imaging of the spine at 8 months of age showed complete, but asymptomatic, collapse of this vertebra (Fig 2A and B).