Abstract: We report a case of an elderly male for the first time in China who was admitted to hospital complaining of repeated edema of both lower limbs for 13 years and recurrence for half a month. This patient had a history of poorly differentiated neuroendocrine carcinoma with unknown primary lesion for 2 years and had undergone two renal biopsies on January 22, 2009 and December 1, 2022, both of which showed membranous nephropathy and no significant difference in light microscopy, immunofluorescence and electron microscopy. The first renal biopsy tissue was positive for phospholipase A2 receptor antibody (PLA2R AB) fluorescence staining and negative for thysopermatin domain containing 7A (THSD7A) staining. The latest renal biopsy tissue was negative for PLA2R staining and positive for THSD7A staining, and the metastatic inguinal lymph node biopsy tissue was positive for THSD7A staining. The final diagnosis was membranous nephropathy secondary to neuroendocrine carcinoma (THSD7A-related) based on clinical, laboratory and pathological findings.

Key words: neuroendocrine carcinoma, secondary membranous nephropa, thythysopermatin domain containing 7A