Metachronous Involvement, Diagnostic Imprecision of Serum Immunoglobulin G4 Levels, and Discordance Between Clinical and Radiological Findings in Immunoglobulin G4-Related Pachymeningitis: A Longitudinal Case Report.

Immunoglobulin G4-related disease is an increasingly recognized, idiopathic systemic disorder that might be associated with elevated serum IgG4 level and tissue infiltration by IgG4-positive plasma cells. We describe the clinical features and biopsy findings in a patient who presented with features suggestive of pachymeningitis and multiple cranial neuropathies. Meningeal biopsy and other laboratory studies established the diagnosis of IgG4-related hypertrophic pachymeningitis. Despite treatment with corticosteroids and mycophenolate mofetil, the patient exhibited a fluctuating progressive course, which stabilized with rituximab, although the radiological findings persisted over 2½ years of follow-up. Our case highlights many important evolving concepts in the disorder, including unusual pathologic features, lack of correlation between serum IgG4 levels and the clinical course, and posttreatment clinicoradiological discordance. We provide potential explanations for this discrepancy, highlight the validity of novel cerebrospinal fluid studies and progressive systemic involvement despite use of immune-suppressive treatments, and emphasize the usefulness of rituximab as a disease-stabilizing agent.

IgG4-Related Neuromyopathy Associated With Recurrent Pleural Effusion.

OBJECTIVE: Immunoglobulin G4-related disease (IgG4-RD) is an increasingly recognized idiopathic systemic disorder associated with elevated serum IgG4 level and tissue infiltration by IgG4-positive plasma cells. Multiple neurological manifestations, including peripheral neuropathy, have been described in IgG4-RD. Our objective is to discuss a case report and review of the literature, which would expand the spectrum of IgG4-RD. METHODS: We describe the clinical features and biopsy findings in a patient with IgG4-RD who presented with features suggestive of neuromyopathy in the setting of recurrent pleural effusion and weight loss. RESULTS: Electrodiagnostic findings were suggestive of an irritable myopathy and polyradiculoneuropathy with primary demyelination and secondary axonal degeneration. Pleural biopsy and laboratory studies confirmed the diagnosis. Improvement was sustained with steroid therapy. CONCLUSIONS: We describe the first case, to our knowledge, of IgG4-related neuromyopathy associated with recurrent pleural effusion. Our case expands the clinical spectrum of IgG4-RD. Neurologists should be aware of this treatable disorder and in the appropriate clinical context consider it in the differential diagnosis of neuromyopathy.

JC Virus PCR Detection Is Not Infallible: A Fulminant Case of Progressive Multifocal Leukoencephalopathy with False-Negative Cerebrospinal Fluid Studies despite Progressive Clinical Course and Radiological Findings.

We describe a case with a false-negative PCR-based analysis for JC virus in cerebrospinal fluid (CSF) in a patient with clinical and radiological findings suggestive of progressive multifocal leukoencephalopathy (PML) who was on chronic immunosuppressive therapy for rheumatoid arthritis. Our patient developed rapidly progressive global decline with clinical and radiographic findings suggestive of PML, but JC virus PCR in CSF was negative. The patient passed away 3 months from the onset of her neurological symptoms. Autopsy confirmed the diagnosis of PML with presence of JC-polyoma virus by immunohistochemical staining. This case highlights the potential of false-negative JC virus PCR in CSF when radiographic and clinical features are suggestive of "possible PML." We review the plausible causes of potential false-negative CSF results and suggest that when the clinical presentation is suspicious for PML repeat CSF analysis utilizing ultrasensitive PCR assay and subsequent brain biopsy should be considered if CSF remains negative. Additionally, appropriate exclusion of other neurologic conditions is essential.