Fibrous soft tissue tumor of neck and shoulder girdle: MR and CT characteristics

Objective: To evaluate MR and CT imagings of desmoplastic fibroblastoma (DF) and aggressive fibromatosis (AF) in neck and shoulder girdle, and to emphasis upon the MRI findings with pathological correlation. Methods: MR and CT appearances of DFs (4 cases) and AFS (3 cases) confirmed by surgical and pathologic findings were retrospective analysed, which were correlated to the pathologic features. Four cases of DF were male patients, with a median age at 48 years. Two cases of AF were female (20, 29 years respectively), and another AF patient was male (79 years). Results: (1) Four DFs were round mass located in the inter muscle space of neck, and the margins were mostly well-circumscribed. Envelope was seen in one lesion on MRI. On unenhanced CT, the masses showed homogeneous low attenuation (2 cases) or slightly low attenuation with several heterogeneous areas in it (1 cases). Enhancement was not obvious on post-contrast CT images. MRI studies were done in two patients. Signal intensity (SI) on MR was homogeneous and heterogeneous one lesion respectively on unenhanced T1-weighted images. Mixed SI as low or high SI nodes within isointense compared with muscle on T2-weighted images. No evident enhancing was noted after administration of gadopentetate dimeglumine. (2) All three lesions of aggressive fibromatosis arose from musculoaponeurotic structures. The masses were irregular margin and appeared elongated, which oriented in the direction of the muscle bundle. On unenhanced CT examination, the masses had poorly defined and isodense relative to adjacent musculature (2 cases). On T1-weighted images, three masses consisted of poormargination and isointensity relative to adjacent muscle. On T2-weighted images, two lesions were heterogeneity of signal, which predominantly slightly high in SI with strip-or node-shape low SI, and one lesion had homogeneous high SI. On post-contrast T1-weighted images, all lesions showed marked enhancement, heterogeneity of signal and irregular margin appeared distinctly. Of them, two masses had claw-shape invasive margin. Conclusion: Both DF and AF, the age range of affected persons different, were fibroblastic origin soft-tissue neoplasms. The distinct imaging characteristics of these two disorders were related to their different pathologic features. Concerning the effect of diagnose and differential diagnose, MRI was predominance over CT. (authors)