Infantile myofibromatosis: The most common fibrous tumor of infancy

Orthopaedic Case of the Month: Rapidly Progressive Shoulder Soft Tissue Mass in an 8-week-old Girl

“…Infantile myofibromatosis is a benign spindle cell tumor [39] characteristically appearing within the first 2 years of life, but with as many as 60% present at birth [7,35,39]. Although MRI findings overlap with congenital fibrosarcoma, the vascular elements and cystic structures seen in our patient are not typical for myofibromatosis [21,35].…”

Pediatric Soft-Tissue Tumors and Pseudotumors: MR Imaging Features with Pathologic Correlation

“…Infantile myofibromatosis (multicentric) or myofibromas (solitary) are the most common fibrous tumors in infancy (10)(11)(12). These are benign tumors that occur mainly in children under the age of 2 years (88% of cases) (10), and about 60% of the cases are diagnosed at birth (11).…”

“…These are benign tumors that occur mainly in children under the age of 2 years (88% of cases) (10), and about 60% of the cases are diagnosed at birth (11). The tumors vary greatly in size from 2.5 cm to 7 cm, and histologically they are formed by nodules with two distinct components, one characterized by bundles of myofibroblasts and the other by more undifferentiated cells arranged around thin-walled, irregularly branching, hemangiopericytomalike blood vessels.…”

“…The multicentric form may be present in the soft tissues, bones, and viscera. The poorer prognosis of myofibromatosis with visceral involvement (25%-35% of multicentric cases) (11), with reported mortality rates as high as 75% (10), is determined by the extent and location of the lesions, with intestinal, cardiac, and, in particular, lung lesions having a poorer outcome (11). Page 6 Although the natural history of most cases of infantile myofibromatosis is spontaneous regression, children affected with visceral disease or diffuse musculoskeletal involvement often develop life-threatening disease before the lesions have had an opportunity to involute (13).…”

A newborn with multiple fractures as first presentation of infantile myofibromatosis

“…Three distinct classifications are now recognized based on the location and involvement of individual lesions: solitary myofibromatosis, congenital multiple myofibromatosis associated with multicentric lesions but without visceral involvement, and congenital generalized myofibromatosis with both cutaneous and visceral involvement. 9 Disease limited to the soft tissues, muscle, and bone has a good prognosis, with expected spontaneous regression of nodules in 1 to 2 years; however, visceral involvement may be fatal generally within the first few months of life, secondary to obstruction of a vital organ, failure to thrive, or infection. Classically, these lesions are described in children younger than 2 years, with two-thirds present at birth.…”