Infantile myofibromatosis: Small bumps pose big problems.

Abstract

Background: Infantile myofibromatosis (IM) is a disorder characterized by proliferation of benign myofibroblastic tumors that typically manifest as solitary or multiple nodules in the skin, muscle, bone, subcutaneous tissues, and visceral organs and can pose significant morbidity and mortality risks, particularly in cases involving visceral organs or causing functional impairment. These soft tissue lesions are the most prevalent benign fibrous tumors that present before age two and can undergo spontaneous regression or are amenable to surgical resection.

Case: A preterm, male infant was born via Caesarean section to a mother with a trichorionic, triamniotic pregnancy following preterm labor. Within the first week of life, several well-circumscribed, smooth, non-tender, and soft nodules with some mobility were noticed along the border of the ribs, across the trunk, back, and lower extremities. Ultrasound imaging confirmed well-circumscribed hypoechoic, intramuscular nodules, and biopsy evaluation showed atypical spindle cell proliferation. The biopsied lesion was PDGFRB-mutated on molecular genetic studies, confirming a diagnosis of myofibromatosis. The infant developed mixed lytic and sclerotic deformities of a variety of bones, necessitating treatment given disease progression.

Conclusion: Successful clinical management with low-dose metronomic chemotherapy (methotrexate and vinblastine) is possible and can treat extensive disease, as seen in our patient.