Renal involvement of lymphomas proven by kidney biopsy: report of 10 cases from a tertiary care center and comparison with the literature.

Lymphomas localized in the kidney are a rare entity that may be challenging to diagnose. We analyzed data from 10 patients with renal involvement of lymphoma diagnosed between 2009 and 2019 on fine needle biopsy from our tertiary center, and compared these with findings of 160 cases reported in the literature. Diffuse large B-cell lymphoma was the main histology subtype (40 and 38% in our sample and in the literature, respectively), followed by low-grade B-cell lymphomas, mostly from the marginal zone (MZ). Altogether, 106 patients had urological inaugural symptoms and 64 had general symptoms. Patients with urological presentation more often had renal masses than diffuse infiltration (p < 0.001), unilateral tumors (p = 0.0036) and low-grade B-cell lymphomas (17 vs 6%, p = 0.043). In both groups, nearly one-fourth of patients had diffuse (stage IV) lymphomas. Overall survival did not differ by the presence of urological/systemic symptoms, stage or aggressive lymphoma status. Notably, 3 of 10 patients from our series had MZ lymphomas associated with primary Sjögren syndrome revealed by acute kidney injury, including one where the autoimmune disease was detected. Lymphoproliferative disorders localized in the kidney are a challenging condition that can lead to detection of aggressive or diffuse lymphomas.