Imaging of spindle cell lipoma

To review the evaluation, diagnosis, and treatment of spindle cell lipoma (SCL) with emphasis on the location of these tumours and the spectrum of magnetic resonance imaging (MRI) and computed tomography (CT) appearances.

The MRI and CT findings of 27 histopathologically proven SCLs were evaluated retrospectively. Imaging features evaluated included margins, percentage visible fat, MRI signal characteristics, oedema, and contrast enhancement patterns.

Patient ages ranged from 18 to 80 years with an average age of 56.5 years. Men were affected twice as frequently as women (M=18, F=9). SCLs ranged in size from 2 to 10 cm, with an average greatest dimension of 5.5 cm. Five lesions (19%) contained no visible fat on CT or MRI, and the leading differential diagnosis of high-grade soft-tissue sarcoma diagnosis was suggested by referring surgeons. Five lesions (19%) had <50% fatty areas, nine lesions (52%) demonstrated >50% but <90% fat at MRI or CT. Only three of 25 lesions (12%) had an appearance of a typical lipoma on unenhanced MRI sequences. All SCLs that were imaged with contrast medium (n = 18) demonstrated some degree of enhancement, with eight (44%) showing marked enhancement, four (22%) showing moderate, and six (33%) minimal enhancement.

SCLs have considerably variable imaging appearances and may have minimal or no visible fat at MRI or CT. Imaging features may make it difficult to distinguish this benign tumour from a potentially higher-grade malignant tumour.