Inflammatory flaccid myelitis in a patient with both anti-CRMP-5 IgG and CNS HIV escape

Anticollapsin-responsive mediator protein 5 (CRMP-5) IgG is an antibody generally associated with small-cell lung cancer, which is known to cause paraneoplastic neurological syndromes, including encephalitis, myelitis and neuropathy. HIV escape is a phenomenon in which a patient with low or undetectable levels of HIV RNA in plasma is found to have elevated levels in cerebrospinal fluid (CSF). We present a case of a 58-year-old HIV-positive woman with undetectable plasma viral load who developed a subacute flaccid paraparesis. Over the course of 4 months, she had a broad inflammatory and infectious workup that was unrevealing until repeat imaging showed an inflammatory myelitis. Workup was notable for elevated HIV RNA copies in CSF, as well as anti-CRMP-5 autoantibodies in serum. Despite changing her antiretroviral therapy and multiple modalities of immunomodulation, the patient failed to respond adequately to treatment. This case illustrates a complex clinical picture with a unique presentation of anti-CRMP-5 myelitis.