MRI-Histological Correlation of Abdominal and Intra-abdominal Desmoid Tumors
Magnetic resonance images of two patients with abdominal and intra-abdominal desmoid tumors were correlated with their histopathological findings. The two patients had a history of excision of polyposis coli. MR-images of the three desmoid tumors of the first patient were composed of two different areas of signal intensity. The inner areas of the tumors had isointensity on T1-weighted images and heterogeneous hyperintensity on T2-weighted images, where as the marginal areas of the tumors had hypointensity on Tl-weighted images and extremely hypointensity on T2-weighted images. The inner areas corresponded to a fibroblast-rich and hypervascular areas, while the marginal areas corresponded to abundant, tight and hypovascular collagenous regions. Most of the second patient's desmoid tumor had isointensity on Tl-weighted images and moderate hyperintensity on T2-weighted images. This tumor included a central area that had been hypointense on Tl-weighted images and extremely hyperintense on T2-weighted images. Most of this tumor was composed of mixed collagen fibers and fibroblasts. The central area consisted of areas of degenerative necrosis and myxoedematous fibroblasts. Abdominal and intra-abdominal desmoid tumors exhibit two patterns on MR-images. Such findings are due to the relative cellularity, amount and distribution of collagen fibers. We considered the extremely hypointensity finding in the marginal areas on T2-weighted images to be characteristic of MR-images of desmoid tumors.