TREM2 and nonpapillary renal cell carcinoma: Analysis of ccRCC through scRNA-seq has identified a macrophage subset that is closely associated with disease recurrence, characterized by the upregulation of proteins such as triggering receptor expressed on myeloid cells 2 (TREM2), apolipoprotein E (APOE), and Complement Component 1, Q subcomponent (C1Q) [227].