Case 212: chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids

History A previously healthy 23-year-old white man presented to the emergency department of our hospital with a 2-month history of dysarthria, progressively worsening vertigo, and difficulty walking. A diagnosis of retinitis pigementosa was made in this patient's childhood. He did not have any history of congenital syphilis. He did not have a history of nausea or vomiting, fever, weight loss, headache, photophobia, seizure, extremity weakness, or sensory disturbance. Physical examination revealed dysarthria, dysmetria, and ataxia. Kernig and Brudzinski signs were absent, and pathergy test results were negative. Laboratory evaluation revealed normal complete and differential blood counts and normal serum chemistry, including a normal serum angiotensin-converting enzyme level. Analysis of his serum was negative for antinuclear antibody (or ANA), cytoplasmic antineutrophil cvtoplasmic antibody (or cANCA), Sjögren syndrome antigens A and B (SS-A and SS-B, respectively), antitissue transglutaminase and antiendomysial antibodies, and paraneoplastic profile. Serum analysis was also negative for human immunodeficiency virus type 1 and type 2 RNA, Venereal Disease Research Laboratory (VDRL) test, rapid plasma regain (RPR), and fluorescent treponemal antibody absorption. Cerebrospinal fluid (CSF) analysis revealed clear fluid, a normal glucose level (64 mg/dL [3.6 mmol/L]; normal range, 40-70 mg/dL [2.2-3.9 mmol/L]), an elevated protein level (97 mg/dL; normal range, 12-60 mg/dL), and an elevated white blood cell count (7/mm(3) [0.007 ×10(9)/L] in tube 1 and 17/mm(3) [0.017 × 10(9)/L] in tube 2) with 84% lymphocytes. CSF immunoglobulin G level was elevated (30.1 mg/dL; normal, <5.9 mg/dL); however, there were no oligoclonal bands. Gram staining, acid-fast staining, and lactic acid, cryptococcal antigen, histoplasma antigen, herpes simplex virus polymerase chain reaction, VDRL, and RPR test results for CSF were negative. CSF did not grow any bacteria, fungus, or acid-fast bacillus at culture. CSF flow cytometry did not reveal a monoclonal lymphoid population. Initial imaging included brain magnetic resonance (MR) imaging. Computed tomography (CT) images of the chest, abdomen, and pelvis were normal (not shown). The patient's clinical symptoms and imaging findings responded to treatment with a high dose of oral steroids. However, the patient's symptoms exhibited clinical and radiologic progression after several attempts to taper the steroid dose.