Skeletal metastases in myxoid liposarcoma: An unusual pattern of distant spread

Background: Myxoid liposarcoma (MLS), the second most common subtype of liposarcoma, occurs predominantly in the extremities of young adults and has a disproportionately high tendency to metastasize to unusual soft tissue locations, before disseminated spread or pulmonary metastases. Anecdotal evidence, mainly supported by isolated case reports, suggests that a subset of these patients also develop bone metastasis, especially within the spine, which was previously under-appreciated. Study Design: In this study we investigate the incidence of osseous metastases in a wellannotated sarcoma database and correlate this endpoint with clinicopathologic and molecular findings. Results: From a total of 230 patients with MLS diagnosis confirmed histologically, who were managed and followed prospectively at MSKCC, 40 (17%) developed skeletal metastases, comprising 56% of all metastatic events. A significant number of these bone metastases were identified early in the disease course, before the manifestation of disease in sites where sarcomas usually metastasize, such as lung. From the time of 1st metastasis, the 5 years median survival was 16%. The majority (78%) of MLS patients developing bone metastases had a histologic high grade primary tumor. The median overall survival for the high grade tumors was 55 months, as compared to 105 months for low grade cases. Eleven (84%) of 13 cases tested by RT-PCR demonstrated a type II TLS-CHOP fusion transcript. Conclusion: These findings suggest that MLS has a high incidence of osseous metastases, with predilection to spine, and often associated with the most common type of TLS-CHOP transcript. Screening should include images of the spine in high-risk MLS patients to exclude spinal metastases.