Primary Mediastinal Liposarcoma

Liposarcomas are rare in the mediastinum. Here, we report the clinicopathologic features of 24 cases of mediastinal liposarcoma. Patients included 13 males and 11 females, with an age range of 3 to 72 years (median 58). Nine tumors were located in the anterior mediastinum, 7 in the posterior mediastinum, 1 in the superior mediastinum, and the precise location was not specified in 7 cases. Of the anterior mediastinal tumors, 3 appeared to arise from the thymus. Tumors were well-circumscribed, multinodular masses and ranged in size from 2.2 to 61 cm in greatest dimension (median 16 cm). Histologic examination revealed that most of the cases were well-differentiated liposarcomas (10), followed by dedifferentiated liposarcomas (8), pleomorphic liposarcomas (4), and myxoid liposarcomas (2). Of the pleomorphic liposarcomas, 2 had areas that resembled myxofibrosarcoma with atypical hyperchromatic spindle cells in a myxoid stroma, but the focal presence of lipoblasts confirmed the diagnoses. Clinical follow-up was obtained in 15 cases (range 1 to 59 mo; median 26). Complete surgical excision was attempted in 13 patients; however, local recurrence was common (5 cases), including 1 patient whose tumor recurred twice. Eleven patients were alive with no evidence of disease at last follow-up (5 well-differentiated, 5 dedifferentiated, and 1 myxoid liposarcoma). Two patients developed distant metastases (dedifferentiated and pleomorphic liposarcoma). One patient was alive with disease (pleomorphic liposarcoma), and 2 died of disease (pleomorphic and dedifferentiated liposarcoma). Overall, mediastinal liposarcomas appear to be similar, in clinicopathologic terms, to liposarcomas arising in the retroperitoneum.