A Case of Spontaneous Remission of Membranous Nephropathy After the Removal of Nerve Epidermal Growth Factor-Like 1 Positive Sigmoid Colon Carcinoma

Recently, the association between membranous nephropathy (MN) and malignancy has been recognized in about 30% of epidermal growth factor-like 1 (NELL-1) positive cases. However, the mechanism of association with MN and malignancy remains under search. In this report, we present a unique case of MN with positive staining for both thrombospondin type-1 domain-containing 7A (THSD7A) and NELL-1. An 80-year-old Japanese woman with nephrotic syndrome (NS) was diagnosed as an immunoglobulin (Ig)G1 subclass predominant secondary MN with weakly positive for THSD7A staining. Then, advanced cancer in the sigmoid colon was found during screening tests for malignancy. After the removal of colon carcinoma, complete remission was achieved at 28 weeks follow-up after operation. Five years later, she remained in remission and passed without recurrence. Thereafter, we examined again newly reported NELL-1 in renal biopsy specimens and found very strong staining along the glomerular capillary walls. Moreover, in resected tumor tissues, NELL-1 was strongly positive at the basal side of adenocarcinoma cells, but THSD7A staining was negative. This case report provides clinical details and highlights the utility of autoantibodies, especially NELL-1, in the diagnosis and treatment of secondary MN with malignancy.