MRI and scintigraphic features of extraabdominal desmoid tumors.

To determine whether extraabdominal desmoid can be correctly diagnosed using both magnetic resonance imaging (MRI) and scintigraphy with pentavalent technetium-99m dimercaptosuccinic acid and gallium-67 citrate, MRI (T1- and T2-weighted images) and scintigraphy were performed in 18 patients with 27 histologically proved extraabdominal desmoid tumors. The extraabdominal desmoid tumors were characterized by positive uptake of pentavalent technetium-99m dimercaptosuccinic acid and lack of uptake of gallium-67 citrate on scintigraphy. These tumors were isointense to skeletal muscle on T1-weighted MRIs and hyperintense on T2-weighted images. They also displayed septum-like internal inhomogeneity and surrounding hypointense capsular band. The combination of scintigraphy and MRI is of value in correctly diagnosing extraabdominal desmoid tumors except in the rare case of fibrotic verylow-grade sarcoma.