Patients with myxofibrosarcoma have a better disease-specific survival than other sarcoma subtypes, but also a higher local relapse rate. This is likely related to the peculiar local growth pattern of these tumors. Adequate surgery should be pursued, while the role of adjuvant therapies need to be investigated.

In STS treated with chemotherapy and radiation therapy, tumor size may be insufficient to render actual tumor response. Tumor attenuation at CT or tumor contrast material enhancement at MR imaging may complement tumor size, thus making Choi criteria more predictive of pathologic response.

We describe 10 solitary fibrous tumors (SFT) with high-grade malignant overgrowth, all of which showed the presence of a synchronous or previous classic SFT/malignant SFT (MSFT) component. Seven were "dedifferentiated," with an abrupt transition from a classic SFT/MSFT to a high-grade component consisting of a nondistinctive high-grade sarcoma in 4 cases and divergent differentiation in 3. The nondistinctive high-grade component consisted of epithelioid and/or spindle cells often associated with overt pleomorphism or small round cell sarcomas. The divergent differentiation featured a rhabdomyosarcoma in 2 cases and an osteosarcoma in 1. Three cases (tentatively called "evolved") showed a gradual transition from classic SFT/MSFT to a nondistinctive high-grade sarcoma or presented features of high-grade sarcoma at the time of metastasis (assessed by fine-needle aspiration cytology) without any component suggesting a diagnosis of classic SFT/MSFT. The high-grade component showed loss of CD34 expression in half of the dedifferentiated SFTs and all of the dedifferentiated SFTs with divergent differentiation, whereas Ki-67 was markedly increased in all of the evaluable cases and paralleled the tumor grade. In 4 cases, the expression and phosphorylation status of key factors that control transcription and protein synthesis were also investigated. Both S6 and 4E-BP1 showed low activation in the low-grade MSFT and a high level of activation in the high-grade component. Seven of the 10 patients died of their disease during follow-up, with a median overall survival of 73 months (range, 5 to 288 mo). The median time to distant metastasis was 156 months after the initial diagnosis, and median overall survival from the first signs of metastasis was 8 months.

The aim of the present work was to improve the understanding of the impact of malignancy grade and myogenic/rhabdomyoblastic differentiation on the natural course of retroperitoneal liposarcoma. All consecutive patients affected by primary well-differentiated (WD)/dedifferentiated (DD) retroperitoneal liposarcoma, surgically treated at our institution between January 2002 and December 2011, were retrospectively evaluated. Tumors were stained for mdm2 and 5 myogenic markers (smooth muscle actin-α, h-caldesmon, calponin, desmin, myogenin). The French National Federation of the Centers for the Fight Against Cancer (FNCLCC) grading system was applied. Overall survival, crude cumulative incidence of local recurrence, and distant metastases were calculated. Multivariable analyses were carried out. A total of 144 patients were identified. Median follow-up was 68 months (interquartile range: 46 to 104 mo). Fifty-two patients were affected by WD/G1 and 92 by DD liposarcoma. Among the latter, 60 were grade G2 and 32 G3. Myogenic differentiation was present in 54 cases (8/52 WD/G1, 27/60 DD/G2, 18/32 DD/G3). Seven cases had a rhabdomyoblastic DD component (1/60 DD/G2 and 6/32 DD/G3). Five-year overall survival rates were 93%, 57%, and 21% for WD/G1 liposarcoma, G2 DD, and G3 DD liposarcoma, respectively, and 75%, 42%, and 29% for liposarcoma without myogenic differentiation, with myogenic differentiation, with rhabdomyoblastic differentiation, respectively (P<0.001). Of note, 5/6 patients affected by G3 DD liposarcoma with a rhabdomyoblastic component died within 8 months. FNCLCC grade and myogenic differentiation significantly predicted the outcome of retroperitoneal liposarcoma. These should be factored into treatment decision-making and possibly used to stratify patients in clinical trials.

Head and neck represent a very critical anatomical site for STS. Achievement of local disease control appears to be crucial, since even LR could be a life-threatening event.