Intramuscular chondroid lipoma: magnetic resonance imaging diagnosis by 'fat ring sign'.

Chondroid lipoma is a rare type of benign lipomatous lesion that can arise from any part of the body, including proximal extremities and limb girdles, trunk, head and neck, breast, and abdominal cavity, in decreasing frequency (1–11). There are a limited number of case reports presenting the imaging findings of this rare tumor and, to the best of our knowledge, this is the second case of chondroid lipoma located in the pelvis. Preoperative diagnosis of chondroid lipoma is difficult due to heterogenous signal changes (1, 3–7, 10). In this study, we present magnetic resonance imaging (MRI) findings of a histopathologically proven chondroid lipoma with a brief review of the literature and describe a new sign that may help preoperative diagnosis of chondroid lipoma.