[Computed tomography and magnetic resonance imaging features of desmoid-type fibromatosis: comparison with the pathological findings].

OBJECTIVE: To explore the computed tomography (CT) and magnetic resonance imaging (MRI) features of desmoid-type fibromatosis, and improve the diagnostic accuracy and understanding of the disease. METHODS: The CT and MRI features of 18 cases of surgically and pathologically confirmed desmoid-type fibromatosis were reviewed retrospectively. Among the patients, 10 received CT pre- and post-contrast scanning, and 8 patients had MRI pre- and post-contrast scanning. The CT and MRI features were analyzed in comparison with the pathological findings. RESULTS: In the extra abdominal cases, the tumors occurred in the head and neck in 3, in the dorsal part of the chest in 2, in the abdominal wall and groin area in 9, and in the peritoneal cavity in 4; concomitant Gardner syndrome was found in 1 case. In 4 cases the tumor occurred within 1 to 3 years after abdominal surgeries. Pathologically, the lesion was hard and composed of fusiform fibroblasts and myofibroblast. The cells showed no obvious heteromorphism with few karyokinesis, growing invasively and recurrent locally but without distant metastasis. Immunohistochemically, the fibroblasts and myofibroblasts expressed vimentin, and the myofibroblasts were positive for SMA. On CT and MRI, the lesion appeared benign with malignant growth pattern, and caused compression of the adjacent organs and vessels or encasement of the vessels; the border was unclear without encapsulation, and necrosis and calcification was scarce. The density and signal of the tumor were well distributed. Twelve patients displayed obvious enhancement and 5 showed uneven enhancement. CONCLUSION: The CT and MRI features of desmoid-type fibromatosis are characteristic, and CT and MRI are valuable modalities for the diagnosis and differential diagnosis of the tumor.