Lipoma with Bone and Cartilage Components in the Left Axilla of a Middle-aged Woman

Lipoma is the most common type of benign soft tissue tumor. However, lipoma containing bone or cartilage is very rare, especially a tumor containing both of these components. We encountered a 59-year-old woman who had a benign lipoma of the infraspinatus muscle that contained both osseous and chondral components. Histopathological examination revealed the presence of chondral and osseous elements mixed with mature adipose tissue. To the best of our knowledge, there has never been a report of benign lipoma containing osteochondral tissue at this location. Therefore, we report the first case of an axillary lipoma with bone and cartilage components.