Aggressive pelvic angiomyxoma and its mimics: can imaging be the guiding light?

To evaluate the imaging characteristics of aggressive angiomyxoma (AA) and identify features which would help to differentiate it from similar appearing lesions.

A retrospective review of departmental records was done and cases where AA was suspected on CT or MRI were included. With histopathology as gold-standard, the cases were grouped into AA or mimics and differentiating features were identified on USG, CT and MRI. Fischer's exact test was applied for the statistical significance of the differentiating features.

18 patients were identified of which 2 were excluded for lack of histopathology records. 10 were AA and 6 mimics which included 2 fibromatoses, 2 neurogenic tumors, and 1 each of germ cell tumor and inflammatory myofibroblastic tumor. On MRI, all AA showed T2 hyperintensity and intense contrast enhancement with characteristic laminated pattern in 7/9 cases. Diffusion restriction was seen in 2/3 cases, cystic component in 4/10 and hemorrhage in 1/10 cases. Pelvic fibromatosis was the closest imaging differential showing laminated pattern in one of the cases.

Large pelvic mass with abdominal/perineal extension in reproductive age female patient should lead to suspicion of AA. Laminated pattern on T₂ weighted images and intense homogeneous contrast enhancement further add to the diagnostic confidence.

This study for the first time describes radiological mimics of AA. Large cystic component, diffusion restriction, hemorrhage and organ infiltration have not been previously described in AA.