Infantile myofibromatosis of the triceps detected by prenatal sonography

A routine prenatal sonographic examination at 36 weeks' menstrual age revea led a solid and slightly inhomogeneous soft-tissue tumor on a fetus's left upper arm. The mass in the left triceps brachii muscle measured 8 x 7 x 5 c m at birth. Because of progressive flexion contracture of the left elbow jo int, at 2 months of age the infant underwent radical resection of the tumor , sparing some muscle fibers. Light microscopic and immunohistochemical stu dies revealed myofibromatosis. Neither tumor nor functional disorder of the arm was evident 3 years after surgery. (C) 1999 John Wiley & Sons, Inc.