Congenital generalized myofibromatosis: a disseminated angiocentric myofibromatosis.

Infantile myofibromatosis occurs in solitary, multiple, and generalized forms, with similar histology but different clinicopathologic and prognostic implications. We report the findings in two male infants with fatal congenital generalized myofibromatosis (CGMF) who presented with multiple dermal and subcutaneous nodules at birth. Imaging studies revealed bony and visceral lesions, which progressed despite chemotherapy. One infant had severe hypercalcemia associated with extensive lytic bone lesions. Both infants died in respiratory failure and had a combination of pulmonary CGMF and diffuse alveolar damage. Involvement of skin, soft tissue, bone, heart, lungs, liver, gastrointestinal tract, and endocrine organs was confirmed at autopsy in each case. A consistent histologic pattern of interlacing fascicles of myofibroblasts with abundant eosinophilic cytoplasm was noted, with variable necrosis and calcifications in some sites. The myofibroblasts displayed vimentin and smooth muscle actin immunoreactivity. The lungs in each case had the presumably early lesions of CGMF with an angiocentric and perivascular growth of myofibroblasts. A similar vascular pattern was present in all affected organs. These two cases demonstrate the extraordinary presentation of CGMF, which suggests its multifocal origin from vascular subintimal mesenchymal or smooth muscle cells whose phenotype is that of myofibroblasts.