IgA Nephropathy with Longitudinally Extensive Transverse Myelitis and Optic Neuritis: Expanding the Spectrum of Systemic IgA Disease

Background: IgA nephropathy (IgAN) is the most frequent primary glomerulonephritis worldwide, yet neurological involvement is rarely encountered. Central nervous system (CNS) manifestations such as demyelinating lesions or optic neuritis have been only sporadically described. Recognition of such associations may broaden understanding of systemic immune injury in IgAN. Case Presentation: A 20-year-old man presented with acute, painful visual loss in the right eye, diagnosed as optic neuritis. One week later, he developed edema, oliguria, and malignant hypertension (220/130 mmHg). Investigations revealed elevated serum creatinine (8.4 mg/dL), non-nephrotic proteinuria (2.3 g/day), and normal complement levels. MRI of the cervical spine demonstrated longitudinally extensive transverse myelitis (LETM) spanning C3–C7. Serologic tests for ANA, ANCA, anti-MOG, and anti-AQP4 antibodies were negative. Kidney biopsy showed crescentic IgA nephropathy with mesangial IgA and C3 deposition. The patient was treated with pulse methylprednisolone followed by intravenous cyclophosphamide and supportive hemodialysis, resulting in partial neurological improvement. Discussion: The concurrent occurrence of IgAN, optic neuritis, and LETM suggests a shared immune-mediated vasculitic process. Aberrant galactose-deficient IgA1 may form circulating immune complexes that deposit in both glomerular and CNS microvasculature, triggering localized endothelial injury and demyelination. The absence of hypocomplementemia and systemic features of IgA vasculitis indicates this represents a rare extrarenal expression of IgAN rather than systemic vasculitis. Conclusion: This case highlights that IgA nephropathy can, albeit rarely, present with demyelinating CNS lesions such as LETM and optic neuritis. Awareness of this association facilitates early immunosuppressive therapy, potentially improving neurological and renal outcomes.