Case Report: Hybrid low-grade fibromyxoid sarcoma and sclerosing epithelioid fibrosarcoma of the retroperitoneum. - Burkitbayev Z; Zhaksylyk A; Ussipbekov B; Uskenbayev T; Kerimkulov A; Sarina Т; Gogolev A; Bolsinbekova S; Sipenova A (Frontiers in oncology, 2026)