Recurrent Pleomorphic Myxoid Liposarcoma in a Patient With Li-Fraumeni Syndrome.

Pleomorphic myxoid liposarcoma is an extremely rare, clinically aggressive subtype of liposarcoma that has been primarily reported in young patients. In this article, we report a case of a pleomorphic myxoid liposarcoma that presented as a second primary neoplasm in a 34-year-old man with history of primary mediastinal large B-cell lymphoma. During the clinical workup, the patient was diagnosed with a germline TP53 gene mutation and Li-Fraumeni syndrome. The tumor, a 2.9 × 2.3 × 2.0 cm well-demarcated and solid mass, was centered in the anterior chest wall soft tissue. Histologically, most of the tumor displayed abundantly myxoid stroma, low cellularity of mostly bland spindle cells, delicate branching capillaries, and lipoblasts; these areas transitioned to small areas whose features were reminiscent of pleomorphic liposarcoma. As assessed by fluorescence in situ hybridization, the tumor showed no DDIT3 (CHOP) (12q13) rearrangements or MDM2 gene amplification. Clinically, the tumor progressed with multiple recurrences and metastasis to the humerus bone. To our knowledge, this is the first case of pleomorphic myxoid liposarcoma diagnosed in an adult with Li-Fraumeni syndrome.