Involvement of the bony orbit in infantile myofibromatosis.

Infantile myofibromatosis is a rare disorder of infancy that can provoke osteolytic lesions. A 15-day-old infant presented with three round, firm lesions located on the forehead, shoulder, and back. Excisional biopsy of the forehead lesion revealed that the tumor was composed of spindle cells resembling normal smooth muscle arranged in short fascicles. Immunohistochemical staining was positive for vimentin and actin. Five months later, the child presented with three new lesions, including one in the superolateral aspect of the left orbit. It is important to recognize the multicentric form of infantile myofibromatosis because, despite its aggressive clinical presentation, the disease is benign and usually does not require extensive surgery or chemotherapy.