膜增生性肾小球肾炎（MPGN）是一种罕见的肾小球疾病，其特征是系膜细胞增多和肾小球基底膜（GBM）增厚。 MPGN 可以是特发性的，也可以与恶性肿瘤、全身免疫复合物紊乱和慢性感染有关。它很少与实体器官肿瘤相关，例如肺癌、胃癌、乳腺癌或前列腺癌。我们报告了一名 MPGN 并存结直肠癌的患者。一名 48 岁男性出现贫血、体重减轻、高血压和肾病综合征。肾活检结果与 1 型 MPGN 相符。抗中性粒细胞胞浆抗体、抗核抗体、抗GBM、乙型肝炎和丙型肝炎血清学标志物以及肿瘤标志物均为阴性。在排除 MPGN 的次要原因后，患者接受了脉冲剂量的甲泼尼龙和单剂量的环磷酰胺治疗。然而，由于贫血和直肠出血恶化，进行了结肠镜检查，诊断为降结肠腺癌。该患者接受了左半结肠切除术和口服皮质类固醇的治疗。癌症治疗后一年内，患者的蛋白尿完全消失，肾功能得到改善。尽管罕见，MPGN 可能与血液系统恶性肿瘤和实体器官肿瘤有关。在开始具体治疗之前，应排除继发性 MPGN 的最常见原因。在我们的患者中，癌症治疗导致肾病综合征随后得到缓解，这表明这种关联不是巧合，而是因果关系。对于患有肿瘤并伴有病因学疑似副肿瘤性肾小球病的患者，应优先治疗潜在恶性肿瘤。© 2024 Galina Severova 等人，由 Sciendo 出版。

Membranoproliferative glomerulonephritis (MPGN) is a rare glomerular disease characterized by mesangial hypercellularity and thickening of the glomerular basement membrane (GBM). MPGN can be idiopathic or associated with malignancy, systemic immune complex disorders and chronic infections. It has rarely been associated with solid organ tumors, such as lung, gastric, breast or prostate cancer. We report a patient with MPGN and coexisting colorectal carcinoma. A 48-year-old man presented with anemia, loss of weight, hypertension, and nephrotic syndrome. The renal biopsy findings were compatible with type 1 MPGN. The antineutrophilic cytoplasmic antibodies, antinuclear antibodies, anti-GBM, serologic markers of hepatitis B and hepatitis C and tumor markers were negative. After ruling out the secondary causes of MPGN, the patient was treated with pulse doses of methylprednisolone and a single dose of cyclophosphamide. However, due to the worsening anemia and rectal bleeding, a colonoscopy was performed, which established a diagnosis of adenocarcinoma of the descending colon. The patient was treated with left hemicolectomy and oral corticosteroids. Within a year after the cancer treatment, the patient experienced a complete resolution of the proteinuria and improvement of the kidney function. Although rare, MPGN can be associated with hematologic malignancies and solid organ tumors. The most common causes of secondary MPGN should be ruled out before starting specific treatment. In our patient, cancer treatment has led to a subsequent remission of the nephrotic syndrome, which indicated that this association was not coincidental but rather causal. In patients with a tumor and concomitant glomerulopathy which is suspected to be paraneoplastic in etiology, the treatment of the underlying malignancy should be prioritized.© 2024 Galina Severova et al., published by Sciendo.