A81.2

HCC Category Mapping

What This Code Means

Progressive multifocal leukoencephalopathy (PML) is a rare and serious brain infection caused by a virus that damages the white matter of the brain, leading to progressive neurological decline. It typically occurs in people with weakened immune systems, such as those with HIV/AIDS or on certain immunosuppressive medications.

Coding Tips

• •Always verify the patient has a confirmed diagnosis of PML, as this is a serious condition requiring specific diagnostic testing (MRI, CSF analysis, or brain biopsy); do not code based on clinical suspicion alone
• •When PML is present, investigate and code the underlying immunocompromised condition (such as B20 for HIV disease) as a secondary diagnosis, as PML is typically an opportunistic infection

Clinical Significance

Progressive multifocal leukoencephalopathy is a devastating demyelinating brain disease caused by JC virus reactivation in immunocompromised patients, particularly those with HIV/AIDS, hematologic malignancies, or on immunosuppressive therapy (notably natalizumab for multiple sclerosis). It carries high mortality and significant disability in survivors.

Documentation Requirements

• ✓Confirmed PML diagnosis via brain MRI showing characteristic white matter lesions (no contrast enhancement, no mass effect)
• ✓JC virus detection: CSF PCR for JC virus DNA or brain biopsy showing viral inclusions
• ✓Underlying immunocompromised condition documented (HIV with CD4 count, transplant status, immunosuppressive medications)
• ✓Neurological examination documenting focal deficits (hemiparesis, visual field cuts, cognitive impairment, ataxia)
• ✓Current antiretroviral therapy or immunosuppressive medication list

Commonly Confused Codes