Atypical appearance of lipomatous tumors on MR images: high signal intensity with fat-suppression STIR sequences.

Lipomatous tumors generally have signal characteristics that allow them to be diagnosed with great accuracy by means of magnetic resonance imaging. These tumors usually have signal intensities similar to those of subcutaneous fat on both T1- and T2-weighted spin-echo images. Previous reports have not, to the authors' knowledge, described the appearance of lipomatous tumors on images obtained with a short-inversion-time inversion-recovery (STIR) sequence, which can be used to suppress signal from fat. Three lipomatous tumors (two liposarcomas and one lipoma) with signal characteristics unlike those of normal subcutaneous fat at all pulse sequences are presented.