Infantile myofibromatosis : report of a rare disease *

The pathogenesis of generalized fibromatosis still remains unknown, despite reports on association with estrogen receptors. This disease is classified into three types as follows: solitary fibromatosis, congenital generalized fibromatosis without visceral involvement, and congenital generalized fibromatosis with both cutaneous and visceral involvement. In most cases, the disease is sporadic, but there are reports on familial occurrence of the three presentations of the disease, so a possible genetic autosomal inheritance (either dominant or recessive) is postulated, with a male prevalence. The range of differential diagnoses is wide and should include other types of fibromatosis, congenital infantile fibrosarcoma, hemangiopericitoma, myofibroblastic tumors, neurofibromas, leyomiomas and nodular fasciitis. The imaging findings of the present case are compatible with those described by other reports in the literature, but one should consider the extent of the lesion, with possible central degeneration in cases of major masses. MRI imposes itself as the best method to evaluate the extent and visceral involvement by the disease. The treatment still remains controversial and includes surgery in cases of obstruction of skin nodules, particularly on the scalp and trunk (Figure 1A). Investigation of upper intestinal obstruction was performed with contrast-enhanced imaging of the esophagus, stomach and duodenum, demonstrating an apparently extrinsic narrowing in the pyloric region. The patient was submitted to exploratory laparotomy that demonstrated the presence of a mass adjacent to the pylorus which was biopsied. Histopathological study revealed spindle cells characteristic of muscle cells, intermingled with fibroblasts, confirming the diagnosis of infantile myofibromatosis (Figure 1B). The lesions workup proceeded with ultrasonography which demonstrated the presence of diffuse, hypoechoic nodules with a more echogenic nucleus affecting the subcutaneous tissue of the trunk, scalp (Figure 2A) and the gallbladder wall (Figure 2B). Computed tomography demonstrated subtly hypodense lesions with homogeneous contrast uptake on the late phase (Figure 3). Magnetic resonance imaging (MRI) demonstrated the presence of nodules in subcutaneous, intramuscular and visceral tissues, with hyposignal on T1weighted sequences (Figure 4A), variable hypersignal on T2-weighted sequences (Figure 4B) and peripheral paramagnetic contrast uptake (Figure 4C). INTRODUCTION