Infantile myofibromatosis is the name for several varieties of benign soft tissue tumors, usually present in infancy or early childhood. It is described as the most common cause of childhood fibrous tumors, however, its incidence is extremely rare, with around 200 documented cases in the medical literature, and no general clinical studies on the disease. It is believed to be genetic in nature, with either a dominant or recessive inheritance model, possibly depending on the manifestation of the disease or other factors. The rarity of the disease, and the possibilty that mild cases may remain undiagnosed, makes it difficult to identify and treat.

Infantile myofibromatosis was first identified in 1954 by Stout, who referred to it as congenital fibromatosis. It later was differentiated into several forms. Congenital solitary fibromatosis refers to a single tumor, usually in muscle tissue but also in bones, skin or viscera; congenital specialized fibromatosis which is multiple tumors in muscle or a single organ; and congenital multiple fibromatosis which refers to multiple tumors in multiple types of tissues and organs. The term "infantile myofibromatosis" was coined in 1981 by Chung and Enzinger, the "myo-" prefix referring to the nature of the tumors, looking microsocopically to be similar to certain muscle cells. Although infantile myofibromatosis is considered the preferred name for the disease, you will find permutations of all the above names in the literature, even today.

Although the tumors are benign in nature, meaning they are non-proliferative and non-invasive, (and IM is decidedly not cancer), their presence in muscles, bones and viscera can cause difficulty for the patient. Infantile myofibromatosis in the internal organs is particularly dangerous, with presentation in the cardiopulmonary system having a reported 75 per cent fatality rate, due to respiratory distress or cardiac failure. Such deaths usually occur before 6 months of age.

The tumors are present usually at birth (beginning in utero) or in the first few months of life. If the tumors do not cause fatality, they will tend to spontaneously regess within one to two years after initial diagnosis. Cutaneous, skeletal, or muscular tumors can leave lytic lesions on regession, which show in the skin as dimpled, depressed areas. In cases where the tumors are life threatening, treatment involves surgical excision (for large, easily differentiable tumors), or low-dose chemotherapy, as well as palliative care for symptoms. Chemotherapy has limited success due to the non-malignant nature of the disease, and there are no clinical studies on its effectiveness, only anecdotal reports of individual cases in the literature. If the tumors are not interfering with life or other bodily function, careful monitoring with MRIs or CT scans are advised, and the disease is allowed to run its course with spontaneous regression. In some cases, isolated tumors will recur later in life, but the generalized form is not known to return as such.

Our child was born with large paraspinal masses and an inability to fully extend his arms and legs. Our pediatrician suspected neuroblastoma or possibly neurofibromatosis (a very different disease) and sent us immediately to a major children's medical center where they instead diagnosed infantile myofibromatosis with visceral involvement, but not in the lungs or heart. We were assured that the tumors would clear up with no long-term effects. We did stretching excercises to help with range of motion and hoped for the best. When he was 5 months old he began having difficulty breathing and was eventually hospitalized, where a chest X-ray showed ground glass opacity and a CT scan showed numerous tumors in the lungs and interstitial lung disease. We confirmed that we had a child with pulmonary involvment of the disease. One of our doctors suggested we probably were the one case in the world last year of pulmonary involvement of the disease.

Since then, he has been steadily improving, with the addition of methotrexate chemotherapy to both reduce the tumors and to improve his symptoms. Careful monitoring of his breathing with pulse oximetry and home oxygen delivery when necessary have kept him basically healthy and stable, with an elevated respiratory rate and increased susceptibility to problems when having a cold. Nearly all the muscle and bone tumors have receded at this point, and range of motion and muscle strength are normal. He is small for his age--partly due to genetics, but also due to failure to thrive at 4-6 months of age, due likely to the pulmonary involvement sapping his strength to breathe, difficulty breast or bottle feeding, and chronic reduced oxygenation.

Our case was studied by some of the world experts in the disease. We are one of the lucky ones in the sense that pulmonary involvement has not been fatal; there is some thought that the 75% quoted fataility rate is historic, before the ability to monitor both oxygen saturation and medical imaging to see the disease, and in historical cases the disease was probably only diagnosed after death during an autopsy. It's our hope that modern medical science, expert medical care, and responsible parenting will bring about complete recovery.


Stout AP: Juvenile fibromatosis: Cancer 7:953-978, 1954
Chung EB, Enzinger FM: Infantile fibromatosis. Cancer 48:1807-1818, 1981.
Coffin CM, Neilson KA, Ingels S, Frank-Gersberg R, Dehner LP: Congenital generalized myofibromatosis: a diseminated angiocentric myofibromatosis. Pediatric Pathology Labratory Medicine 1996 Jul-Aug;15(4)581-587.
Yonsei Medical Journal 1989 December;30(4):376-382 at
Caglya, F, Infantile myofibromatosis in a newborn: a case report. Turkish Journal of Pediatrics 2003;45:59-63, at
Hatzidaki E et. al., Infantile myofibromatosis with visceral involvement and complete spontaneous regression, Journal of Dermatology 2001 Jul;28(7):379-382.
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