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Case Reports

Abstract

A 2-day-old full-term healthy girl presented with a large congenital ulcerated nodule on the lower lip previously detected on prenatal ultrasound at 30-weeks’ gestation. Further examination revealed firm, violaceous nodules on the right nasal root and left upper back. Given the lesions’ morphologies, multifocal distribution, and lack of vascular enhancement on imaging, the clinical differential diagnosis was broad, including metastatic neuroblastoma, rhabdomyosarcoma, and myofibroblastic tumor of infancy. Infantile myofibromatosis was a top consideration given a reported paternal history consistent with myofibromatosis. MRI of the infant’s face and head did not show evidence of CNS lesions. Laboratory workup (CBC, BMP and coagulation studies) was unremarkable.

Punch biopsy of the upper back nodule revealed a dense infiltrate of cytologically bland spindle cells arranged in intersecting fascicles, with some areas of myxoid stroma, and angulated to focally 'staghorn' vessels within the tumor. The histopathologic differential diagnosis included myofibromatosis and infantile fibrosarcoma, which in a minority of cases may mimic myofibroma. A panel of immunohistochemical stains showed lesional cells stained positive for CD34 and SMA and negative for CD31, ERG, desmin, S-100, Sox-10, GLUT-1, EMA, pan-keratin and pan-TRK. An infantile myofibromatosis molecular genetic panel identified a heterozygous pathogenic variant, c.1681 C>T (p.Arg561Cys), in the PDGFRB gene.

Taken together, these findings confirmed a diagnosis of infantile myofibromatosis, a rare mesenchymal proliferative disorder with potential visceral involvement. Whole body MRI did not show evidence of visceral lesions in this case, so conservative management was pursued with multidisciplinary guidance for continued surveillance.