Membranous nephropathy in a patient with pulmonary tuberculosis infection and lung adenocarcinoma: a case report

Abstract

We report a case of membranous nephropathy (MN) in a patient with tuberculosis infection and lung adenocarcinoma. A 50-year-old Filipino woman underwent a renal biopsy for the evaluation of proteinuria and hematuria. Immunofluorescence analysis revealed positive staining of IgG in the glomerular basement membrane and mesangial matrices, while electron microscopy demonstrated the presence of sub-epithelial deposits, suggesting MN. To screen for secondary causes of MN, we conducted a computed tomography (CT) scan of the chest and abdomen, which revealed a ground-glass opacity in the middle lobe of the right lung and an enlarged paraaortic lymph node. A T-SPOT test was positive, suggesting the possibility of a latent tuberculosis infection, as she was asymptomatic. A follow-up chest CT scan showed persistent presence of the ground-glass opacities, suggesting a non-infectious cause. Video-assisted thoracoscopic resection of the middle right lobe and partial resection of the lower right lobe were performed because the possibility of lung cancer could not be excluded. Notably, pathological analysis of the lung revealed adenocarcinoma in the middle lobe and epithelioid granuloma in the lower lobe, suggesting an active tuberculosis infection. One month after surgery, anti-tuberculosis treatment was initiated. Thereafter, her proteinuria, which had increased to 6 g/gCre preoperatively, began to decrease. Five months after surgery, the patient achieved complete remission. The speed of remission suggests that tuberculosis likely played a primary role in the etiology of MN. Our case underscores the importance of screening tests for infections and malignancies in patients with MN, even if suggestive symptoms are absent.

Keywords: Lung adenocarcinoma; Lymphadenopathy; Membranous nephropathy; Tuberculosis.

Fig. 1

Renal biopsy specimens. a Periodic acid-Schiff staining. b Periodic acid-methenamine silver staining. c Immunofluorescent IgG staining. d IgG subclass immunohistochemistry. e Electron microscopy, original magnification, × 8000; f Electron microscopy, original magnification, × 15,000; g PLA₂R immunohistochemistry

Fig. 2

A CT scan. a A red arrow indicating a ground-glass opacity in the middle lobe of the right lung six months before partial lung resection. b A red arrow indicating a ground-glass opacity in the middle lobe of the right lung one day before partial lung resection. c A red arrow indicating a consolidation in the lower lobe of the right lung one day before partial lung resection. d A red arrow indicating a paraaortic lymph node seven months before anti-tuberculosis treatment began. e A red arrow indicating a paraaortic lymph node three months after anti-tuberculosis treatment began

Fig. 3

Right lung biopsy specimens. a Adenocarcinoma in the middle lobe. b Epithelioid granuloma with necrosis in the lower lobe

Fig. 4

Trend of proteinuria and serum albumin levels during the clinical course