Infantile myofibromatosis

Christopher Francois, M.D.

Frank Prendergast, M.D.

Children's Memorial Hospital


Three day old female presenting with left thigh mass


Infantile myofibromatosis, myofibroma, US, MRI 672

Publication Date: 2005-02-01


Three day old female presenting with left thigh mass.


MR imaging demonstrates a heterogeneous, predominantly low T1 (image 1), high T2 (images 3-4) signal lesion in the left thigh. Contrast-enhanced image demonstrate peripheral enhancement (image 2).

Ultrasound (images 5-6) demonstrates well circumscribed heterogeneous lesion in the left thigh with peripheral vascularity.


Metastatic neuroblastoma, soft-tissue sarcoma, congenital-infantile fibrosarcoma, leiomyoma, neurofibroma, hyaline fibromatosis, and deep hemangioma


Infantile myofibromatosis is, while rare, the most common fibrous tumor in infancy and can occur in the skin, muscle, bone or viscera. Approximately half of the lesions are solitary. One third are multifocal without visceral involvement with the remainder presenting as multifocal disease with solid organ involvement. While most cases occur in infants less than two years of age, they can present in older children or adults.

Prognosis for solitary or multifocal lesions without visceral disease is excellent. Morbidity and mortality in patients with solid organ involvement is usually due to obstruction, failure to thrive, or infection. While myofibromas can occur in any organ system, the cardiopulmonary and gastrointestinal organs are most commonly involved. Skeletal lesions most often occur in the skull and long bones.

The work-up of these patients should include a skeletal survey, chest radiograph in addition to cross-sectional imaging to evaluate the extent of disease.

US - The ultrasound characteristics of these lesions is variable. Lesions typically are heterogeneous with a predominantly hypoechoic center. Internal vascularity is usually not detected with color Doppler. However, flow can occasionally be detected along the periphery.

CT - These lesions are usually slightly lower in attenuation than surrounding muscle with mild peripheral enhancement. Calcifications are rare.

MRI - Myofibromas have a very heterogeneous appearance on MR imaging. They typically present as well circumscribed tumors that are predominantly low in signal intensity on T1-weighted images and high in signal intensity on T2-weighted images. With contrast-enhancement, these lesions demonstrate peripheral enhancement, with an appearance suggestive of central necrosis.


  1. GL Johnson, BL Baisden, EK Fishman. Infantile myofibromatosis. Skeletal Radiol. 1997; 26: 611-614.
  2. J Dubois, L Garel, M David, J Powell. Vascular Soft-Tissue Tumors in Infancy: Distinguishing Features on Doppler Sonography. Am. J. Roentgenol. 2002; 178: 1541-1545.
  3. SJ Counsell, C Devile, E Mercuri, JM Allsop, R Birch, F Muntoni. Magnetic resonance imaging assessment of infantile myofibromatosis. Clin Radiol. 2002; 57: 67-70.
  4. K Koujok, RE Ruiz, RJ Hernandez. Myofibromatosis: imaging characteristics. Pediatr Radiol. 2004; published online Nov 19.

6 images