Lipomatous lesions of the head and neck region: imaging findings in comparison with histological type.

PURPOSE: Aim of the study is to demonstrate the main role of magnetic resonance imaging in the identification and characterization of lipomatous lesions of the head and neck.

MATERIALS AND METHODS: CT and MRI findings of 78 patients (43 male, 35 female) aged 12-80 (mean 47.5) years surgically treated for lipomatous lesions of the head and neck region between January 1995 and June 2005 were retrospectively analysed and correlated with the histological results.

RESULTS: On CT images, lipomas and fibrolipomas appeared as smooth (38/50 cases) or lobulated (12/50 cases) well-defined masses associated with moderate displacement of surrounding tissues; tumours had high signal intensity on MR T1-weighted images, with relative decreasing signal on T2-weighted images. Infiltrating lipomas appeared as expansile ill-defined masses with heterogeneous signal. Angiolipomas showed a characteristic contrast enhancement on both CT and MRI. In one case of sialolipoma, the lesion appeared markedly heterogeneous in signal. MR and CT images of Madelung's disease showed multiple symmetrical lipomatous masses involving the neck region. Intraosseous fatty lesions appeared as well-defined hypodense masses sometimes associated with cortical expansion and disruption.

CONCLUSIONS: Both CT and MRI exams are useful for detecting lipomatous lesions. MRI, however, is more accurate in the evaluation of their extent and in the characterisation of uncommon lipomatous lesions of the head and neck, and intravenous administration of gadolinium better depicts the margins of the tumour and its vascularisation.