A chondroid lipoma in the muscle of the trunk back: a rare case report and review of the literature

Chondroid lipoma, a benign soft tissue tumor and a subtype of the lipoma, is extremely rare and can be easily mistaken as myxoid liposarcoma and myxoid chondrosarcoma. Here we report a chondroid tumor in the muscle of the trunk back in a 50-year-old female. The tumor was noticed by the patient and growing slowly for a year and had a rapid growth for 3 months before she came to the hospital. The tumor was about 4 cmx3 cm and entirely encapsulated. The cutface was fat-like without hemorrhage and necrosis. The tumor cells showed lipoblastic differentiation and were arranged in nests and embedded in a chondroid matrix. Immunostaining shows diffusely positive vimentin expression, weak S-100 expression and very low Ki67-index of less than 1%. According to these findings, it was diagnosed as a chondroid. The patient experienced no relapse at a 3 years follow-up after total resection of the tumor. Chondroid lipoma is an extremely rare benign adipose tumor which should be carefully differentiated with myxoid liposarcoma and myxoid chondrosarcoma to avoid overtreatment.