Subcutaneous Angiolipoma : Magnetic Resonance Imaging Features with Histological Correlation

[Abstract] [Purpose] : Despite producing pain, angiolipoma is sometimes misdiagnosed as an ordinary small lipoma, which is usually not associated with pain. Few reports have described magnetic resonance (MR) imaging findings of angiolipoma. The aim of the present study was to clarify the MR imaging features of angiolipoma. [Materials and Methods] : The MR imaging findings of 11 lesions in 7 patients were reviewed and compared with histopathological findings. [Results] : The MR imaging features of these lesions were the presence of fat nodules with or without areas of low signal intensity on T1- and T2-weighted images. The location of the low-signal-intensity areas varied. The low-signal-intensity areas were mainly in the peripheral portion of 3 lesions and in the central portion of 5 lesions. No or few low-signal-intensity areas were observed in 3 lesions. In the lesions with peripheral low-signal-intensity areas, lesion marginations were well defined, and the lesions were easily recognized as mass lesions. In the lesions with only central low-signal-intensity areas, marginations were poorly defined, and the lesions were not easy to recognize as mass lesions. In the lesions with few or without low-signal-intensity areas, marginations were invisible. Histopathological studies indicated that the low-signal-intensity areas on T1- and T2-weighted images corresponded to areas of dense capillary proliferation. In lesions with few or without low-signal-intensity areas on MR images, capillaries were thinly spread over almost the entire lesion area. [Conclusion] : The MR imaging features of angiolipoma are fat nodules with or without low-signal-intensity areas of various size and location on T1- and T2-weighted images.