Pleomorphic liposarcoma of the uterine corpus with focal smooth muscle differentiation.

We describe a rare case of a pleomorphic liposarcoma (>95%) of the uterine corpus with focal leiomyosarcomatous (<5%) differentiation, and review the literature on 10 purely mesenchymal liposarcomatous tumors of the uterine corpus reported earlier. The patients, including this case, ranged in age from 45 to 78 years (mean and median 59 y) and frequently presented with abnormal uterine bleeding and/or abdominal pain. The tumors were typically large (average tumor size 15.79 cm, range: 7 to 28 cm), and displayed a cut surface with hemorrhage and gross degeneration. Most tumors were confined to the uterus after initial evaluation. Follow up was available in 10 (91%) of the 11 patients. Five (50%) of the 10 patients showed no evidence of tumor recurrence or metastases at an average follow-up of 30.4 months. The remaining 5 patients experienced recurrence within the first year of their extirpative operations. However, 2 (40%) of the 5 patients who showed no recurrence had limited follow-up (2 and 6 mo). After excluding cases without follow-up and nonrecurring cases with less than 1-year follow-up, the overall rate of recurrence or metastases was 62.5% (5 of 8). Eight (72.7%) of the 11 reported cases were associated with smooth muscle neoplasia, including 2 cases designated as "mesenchymoma" with liposarcomatous, leiomyosarcomatous, and osteosarcomatous elements; 1 case of a myxoid liposarcoma arising from a leiomyoma; and 5 cases of tumors with varying amounts of leiomyosarcomatous and liposarcomatous components. On the basis of this review, we postulate that a significant subset of liposarcomatous tumors of the uterus may actually represent an unusual form of divergent differentiation of leiomyosarcomas. This may have adjuvant management implications for patients with these rare tumors.