Spinal IgG4-related hypertrophic pachymeningitis with spinal cord compression case report

Background Back pain is a leading reason for patients to seek medical attention. Although musculoskeletal causes are common, patients can also present with rarer etiologies. Case Description A 50-year-old man presented with 2 months of isolated upper back pain initially suspected to be secondary to overuse muscular strain. During the next 3 months, his pain worsened, and he developed lower extremity dysesthesia and subjective weakness, despite normal neurological examination findings. Nonrevealing laboratory workup included normal muscle enzymes, C-reactive protein, urinalysis, and human leukocyte antigen B27. Magnetic resonance imaging revealed a normal brain but a hypointense C7–T5 epidural mass, prompting a neurosurgical recommendation for laminectomy with evacuation of the suspected hematoma. His symptoms fully and promptly resolved after a 5-day course of prednisone 40 mg. When his symptoms recurred within 2 months, he underwent T4-T5 laminectomy with biopsy of a mass confluent with the dura mater. Initial pathological examination revealed fibrotic tissue of unclear etiology with polyclonal lymphoid infiltrate but no malignant cells, vasculitis, or granulomas. After months of recurrent, steroid-responsive symptoms, he presented to the rheumatology clinic. Repeat spinal magnetic resonance imaging demonstrated progression of epidural thickening with suspected spinal cord compression. Previous biopsy samples were then immunostained for IgG4, revealing focally dense IgG4-positive plasma cells, up to 29 cells per high power field, consistent with spinal IgG4-related hypertrophic pachymeningitis. He began rituximab therapy with a prednisone taper and demonstrated symptomatic and neurologic improvement with successful withdrawal from corticosteroids. Conclusions To the best of our knowledge, the present case represents the 12th reported case of spinal IgG4-related hypertrophic pachymeningitis. An early diagnosis and treatment could prevent progression to permanent neurological impairment and functional disability.