They include infantile myofibromatosis, fibromatosis colli, extraabdominal desmoid tumor, and aggressive infantile fibromatosis. Radiographs typically reveal a nonspecific soft-tissue mass, and calcification is common only in juvenile aponeurotic fibroma. Involvement of adjacent structures is common, reflecting the infiltrative growth pattern often seen in these lesions. MR imaging may show characteristic features of prominent low to intermediate signal intensity and bands of low signal intensity representing highly collagenized tissue. However, fibromatoses with less collagen and more cellularity may have nonspecific high signal intensity on T2-weighted images.
Local recurrence is frequent after surgical resection due to the aggressive lesion growth.
It is important for radiologists to recognize the imaging characteristics of musculoskeletal fibromatoses to help guide the often difficult and protracted therapy and management of these lesions. Differentiating between these two entities is important clinically because IAF is a benign tumor whereas GISTs frequently have malignant potential. In this study, the authors identified 13 cases of IAF with prominent involvement of the bowel wall as well as 35 GISTs of the small intestine, colon, or mesentery and analyzed their clinical, gross, histologic, immunophenotypic, and ultrastructural characteristics to identify important distinguishing features. Both types of tumors tended to be large, but GISTs were soft and lobulated with hemorrhage, necrosis, or cystification whereas IAFs were firm, tan, and homogeneous. These entities can be distinguished primarily by their light microscopic and ultrastructural features but there is a notable overlap in their immunohistochemical profiles.