CD99 and neoplasm: UPS tumors often exhibit elevated PD-L1 and PD-1 expression, increased T-cell infiltration (positive for CD3, CD8, CD127/IL7 receptor, CD99, CD68, CD10, and negative for TIGIT), and abundant tumor-associated macrophages (positive for CD163, ionized calcium-binding adaptor molecule 1 (Iba1), MSR1, CD204, and SIRPα), alongside a high tumor mutational burden (TMB-H) compared with other STS subtypes [38,83,84,85,86,87,88,89,90,91,92].