Coexistence of Fabry disease with IgM nephropathy

Abstract Rationale: Coexistence of Fabry disease and IgM nephropathy is rare. The varying severity and unapparent clinical manifestation of Fabry disease makes it difficult to recognize when coexisting with another more prevalent cause of nephropathy requiring electron microscopy and genetic testing to confirm their coexistence. Patient concerns: A 54-year-old female presented with proteinuria without any clinical signs or family history of Fabry disease. Diagnoses: Immunostaining of the renal biopsy identified mesangial IgM deposition diagnosing it as IgM nephropathy. The light microscopy indicated prominent vacuolization of podocytes. Further examination of toluidine blue stained semi-thin sections and electron microscopy revealed blue bodies and myelin bodies in the cytoplasm of podocytes, respectively. Mutation analysis detected missense mutation establishing the diagnosis of coexisting Fabry disease. Interventions: The patient was treated with angiotensin-converting enzyme inhibitors. Enzyme replacement therapy was not administered due to financial constraints. Outcomes: After 2 months of treatment the patient demonstrated urine protein to creatinine ratio of 0.21 g/g. Lessons: Identifying coexistence of Fabry disease with other nephropathy requires meticulous pathologic investigations including electron microscopy especially when Fabry disease presents with atypical phenotype.