Case 342: IgG4-related Hypertrophic Pachymeningitis

HISTORY: A 70-year-old woman presented with progressively worsening midback pain over 2 months, radiating in a wraparound distribution to the lower ribs. Initially, the pain was confined to the night but eventually began to persist during the day, worsening with sitting and lying down. The pain was severe and unresponsive to paracetamol and nonsteroidal anti-inflammatory drugs. She reported no bowel or bladder issues and no weakness, numbness, or history of trauma. There was no radiculopathy in either lower extremity. She had no fever, weight loss, or history of using blood thinners. She was a former smoker with a prior transbronchial biopsy for a pulmonary nodule that was negative for malignancy or infection. She had a sister diagnosed with ovarian cancer. Physical examination demonstrated normal vital signs; preserved orientation to person, place, and time; and intact short-term and long-term memory. She had normal gait and coordination. Muscle strength was rated five of five for all four extremities, with intact sensation. Deep tendon reflexes were rated two or higher throughout. No clonus was present, and Hoffmann sign was negative. A lumbar puncture was performed at the bedside. Cerebrospinal fluid (CSF) analysis (Table) revealed an increased protein level (379 mg/dL [3790 mg/L]; reference range: 7-35 mg/dL [70-350 mg/L]) and a mildly decreased glucose level (41 mg/dL [2.3 mmol/L]; reference range, 45-70 mg/dL [2.5-3.9 mmol/L]). There was an elevated CSF lymphocyte count (94 cells/μL; reference range, 0-10 cells/μL). CSF cytologic examination and flow cytometry revealed small lymphoid cells without immunophenotypic abnormalities, suggesting an absence of clonal proliferation. Two oligoclonal bands were present in the CSF (absent in the concurrent serum sample), which was below the threshold for oligoclonal band positivity (four bands). CSF culture, DNA tests for cytomegalovirus and Epstein-Barr virus, polymerase chain reaction tests for herpes simplex virus 1 and 2 and varicella-zoster virus, and autoimmune encephalopathy panels were negative. Both serum and CSF angiotensin-converting enzyme levels were within normal limits. [Table: see text] At initial presentation, imaging of the spine and spinal canal included unenhanced CT of the thoracic spine and contrast-enhanced MRI of the thoracic spine. Contrast-enhanced MRI of the brain was also performed, which was unremarkable aside from chronic microvascular ischemic changes. Specifically, no dural thickening or intracranial enhancing lesion was identified. Contrast-enhanced CT of the chest, abdomen, and pelvis was unremarkable, showing no pulmonary nodules, features of primary malignancy, or lymphadenopathy. Incidental findings included emphysema, likely related to the patient's smoking history. The patient subsequently underwent T6 laminectomy followed by treatment with a glucocorticoid and rituximab. Follow-up thoracic spine MRI was performed 2 months after the initial presentation.