B2M and lymphoma: MCT1-positive immunoreactivity was significantly associated with elevated serum β2-microglobulin (β2-M, a small circulating protein that rises with disease activity and serves as a marker of tumor load and adverse outcomes in lymphomas) level, male sex, and Ki-67 ≥ 30%; MCT4-positive immunoreactivity was significantly associated with Ki-67 ≥ 30%; CD147-positive immunoreactivity correlated significantly with low-grade FL.