Infantile myofibromatosis

Infantile myofibromatosis (also known as congenital generalized fibromatosis or infantile myofibromatosis type 1 and type 2) is a rare mesenchymal disorder characterized by the development of benign fibrous tumors (myofibromas) in the skin, muscles, bones, and occasionally the visceral organs. It is the most common fibrous tumor of infancy. The condition typically presents at birth or within the first two years of life as firm, flesh-colored or purplish nodules in the skin, subcutaneous tissue, skeletal muscle, or bone. Lesions may be solitary (solitary infantile myofibromatosis) or multicentric (multiple infantile myofibromatosis), and the multicentric form may or may not involve visceral organs. When limited to the skin, soft tissues, and bone, the prognosis is generally excellent, as many lesions undergo spontaneous regression within the first few years of life. However, the multicentric form with visceral involvement (affecting organs such as the lungs, gastrointestinal tract, heart, or liver) carries a significantly poorer prognosis and can be life-threatening due to organ compression or dysfunction. Skeletal lesions typically appear as well-defined osteolytic defects on imaging. Treatment depends on the extent and location of disease. For solitary or multicentric disease without visceral involvement, observation alone may be appropriate given the tendency for spontaneous regression. Surgical excision may be considered for symptomatic or strategically located lesions. In cases with visceral involvement or life-threatening disease, chemotherapy (often low-dose vinblastine and methotrexate or other regimens) has been used with variable success. Genetic studies have identified germline mutations in the PDGFRB gene and, less commonly, in NOTCH3 as causative in familial cases, which has opened the possibility of targeted therapies in severe cases.

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