Primary subcutaneous myxoid liposarcoma: a clinicopathologic review of three cases with molecular confirmation and discussion of the differential diagnosis.

BACKGROUND: Myxoid liposarcoma typically presents as a deep-seated mass in the lower extremity of adults. Presentation as a primary subcutaneous tumor is rare. Here we discuss clinicopathologic characteristics of three such cases and their differential diagnosis to alert dermatopathologists to this unusual clinical presentation of a potentially aggressive entity.

METHODS: Cases of myxoid liposarcoma were retrieved from archives and consultation files. Inclusion required location above the subcutaneous fascia with no evidence of a metastatic origin. Clinicopathologic features were retrospectively reviewed. Fluorescence in situ hybridization for DDIT3 (CHOP) gene rearrangement was performed on all cases.

RESULTS: The tumors affected young adults (two males and one female, mean 36 years, range 32-40 years). No prior history of myxoid liposarcoma or deep soft tissue mass was identified. The tumors occurred in the foot, thigh and hand. All demonstrated multilobular architecture with abundant myxoid stroma, prominent branching capillary vascular network and lipoblastic differentiation. No dermal involvement was seen. Round cell features were identified in one case and represented <5% of the tumor. All patients remain disease-free following local excision only at 6, 8 and 13 months.

CONCLUSIONS: Myxoid liposarcoma can rarely present as a primary subcutaneous mass and should be considered in the differential diagnosis of cutaneous myxoid tumors in adults.