Clinicopathological and immunohistochemical analysis of the risk factors of recurrence of atypical lipomatous tumor/well-differentiated liposarcoma of the extremities.

Atypical lipomatous tumors/well-differentiated liposarcomas (ALT/WDLPS) are low-grade, slow-growing, and locally aggressive tumors. We investigated clinical outcomes and recurrence factors for ALT/WDLPS of the extremities. This is retrospective study across three institutions which included patients who underwent surgery for ALT/WDLPS from 2001 to 2019. We collected the data such as the patient demographics, anatomical locations of the tumors (subcutaneous, intramuscular, intermuscular, upper extreme/lower extremity), immunohistochemical data, and the resected margin status. The following variables were evaluated as potential recurrence factors: age, sex, tumor diameter, anatomical location of the tumor, immunohistochemical results, and resected margins. The 5- year local recurrence-free survival rate (RFS) was calculated and differences in survival were assessed. Sixty-two patients were identified, including 29 men and 33 women. The mean age was 63.7 years (range, 34-82 years). The average maximum tumor diameter was 15.9 cm (range, 5-28 cm). The maximum tumor diameter (≥20 cm) was significantly associated with local recurrence (p=0.042). Ten patients (16.1%) developed local recurrence, and the mean time to recurrence was 48.4 months (range, 5-161 months). In our series of 62 patients, the differences in local recurrences were not statistically significant for age, sex, tumor site, surgical margin (R0 or not) and immunohistochemical results. Tumor diameter ≥20 cm, which was the only identified factor for recurrence.