Histologically, infantile myofibromatosis shows a biphasic pattern or zoning phenomenon. A staining area contains plump myoid spindle cells with eosinophilic cytoplasm arranged in nodules, short fascicles or whorls, with or without hyalinization. This pattern may however, be distributed haphazardly throughout the lesion. A central or dark staining area contains round or polygonal cells with slightly pleomorphic hyperchromatic nuclei or small spindle cells typically arranged around a distinct hemangiopericytoma-like vascular pattern. Myofibromatosis shows a positive immunoreaction with smooth muscle actin and vimentin, but is negative for S100. Prognosis depends on the extent of visceral involvement and it may be fatal
The differential diagnosis includes neurofibroma, nodular fasciitis, infantile fibromatosis, fibrous histiocytoma, fibrosarcoma.
Histologically, infantile myofibromatosis shows a biphasic pattern or zoning phenomenon. A staining area contains plump myoid spindle cells with eosinophilic cytoplasm arranged in nodules, short fascicles or whorls, with or without hyalinization. This pattern may however, be distributed haphazardly throughout the lesion. A central or dark staining area contains round or polygonal cells with slightly pleomorphic hyperchromatic nuclei or small spindle cells typically arranged around a distinct hemangiopericytoma-like vascular pattern. Myofibromatosis shows a positive immunoreaction with smooth muscle actin and vimentin, but is negative for S100. Prognosis depends on the extent of visceral involvement and it may be fatal
The differential diagnosis includes neurofibroma, nodular fasciitis, infantile fibromatosis, fibrous histiocytoma, fibrosarcoma.