Case report of IgG4-related hypertrophic pachymeningitis with multisystem involvement and spinal cord compression treated with rituximab

Abstract

Case Presentation: A 74-year-old woman presented with a two-year history of progressive frontal and retro-orbital headache, associated with diplopia, left eye pain, and progressive visual loss. Initial evaluation in 2023 revealed multiple cranial nerve involvement (III and VII), proptosis, and imaging findings suggestive of orbital inflammatory disease and pachymeningeal enhancement. Systemic investigation demonstrated pulmonary nodules and gastric wall thickening, raising suspicion for neoplastic or inflammatory disease. The patient underwent bilateral orbital mass biopsy and pulmonary biopsy, demonstrating lymphoplasmacytic and histiocytic inflammatory patterns without evidence of malignancy. Over time, she developed cognitive decline and persistent headache. Neurological examination revealed tactile and temperature hypoesthesia, along with impaired vibratory sensation up to the knee level, suggestive of spinal cord involvement. Follow-up MRI in 2025 demonstrated diffuse hypertrophic pachymeningitis with homogeneous contrast enhancement and extension to the cervical spine, resulting in spinal cord compression. Laboratory evaluation revealed elevated serum IgG4 levels. CSF analysis excluded infectious and neoplastic etiologies. The patient was treated with high-dose corticosteroid pulse therapy followed by rituximab, resulting in marked clinical improvement, including resolution of headache, cognitive symptoms, and stabilization of neurological deficits. Discussion: IgG4-related disease (IgG4-RD) is a systemic fibroinflammatory disorder characterized by tumefactive lesions, lymphoplasmacytic infiltrates, and variable elevation of serum IgG4 levels. Central nervous system involvement is rare, with hypertrophic pachymeningitis representing one of its most severe manifestations. Patients typically present with chronic headache and cranial neuropathies; however, disease progression may lead to spinal involvement and compressive myelopathy, as observed in this case. Imaging findings are often nonspecific, requiring careful differential diagnosis with infectious, neoplastic, and other autoimmune conditions. Histopathological findings, even when not initially specific for IgG4-RD, are essential for diagnostic suspicion in the appropriate clinical context. Corticosteroids are the first-line treatment, but relapse is common. Rituximab has emerged as an effective therapy in severe or refractory cases, particularly in those with neurological involvement. Final Comments: Early recognition of IgG4-related pachymeningitis is essential to prevent irreversible neurological damage. This case highlights the importance of timely immunosuppressive therapy, with rituximab showing significant clinical benefit.