CT and MR imaging of desmoplastic fibroblastoma.

Desmoplastic fibroblastoma (collagenous fibroma) developing as a slowly enlarging lower abdominal mass is described. The lesion had inhomogeneous low signal intensity (SI) on T1-weighted images, and mixed SI as low SI within high SI on T2-weighted images. On post-contrast T1-weighted images, the mass showed inhomogeneous enhancement. Histologically, the areas showing low SI on both post-contrast T1- and T2-weighted images consisted of dense collagenous components and reduced cellularity compared with the areas showing high SI on them.