Polyradiculoneuropathies associated with immune checkpoint inhibitors: are we facing a new nosological entity?

Immune checkpoint inhibitors (ICIs) like ipilimumab, nivolumab, and pembrolizumab are increasingly used to treat advanced cancers. While they improve survival, they can cause immune-related adverse events (irAEs), including neurological issues affecting the peripheral nervous system (PNS). Among these, peripheral neuropathies such as acute inflammatory demyelinating polyneuropathy (AIDP) and chronic inflammatory demyelinating polyneuropathy (CIDP) are common. Diagnosing these conditions can be difficult, especially when caused by ICIs, leading to potential misclassification and suboptimal treatment. A 48-year-old woman with melanoma on pembrolizumab developed progressive weakness, sensory disturbances, and areflexia after two cycles of treatment. Neurological evaluation suggested AIDP, and she was treated with intravenous immunoglobulin (IVIg), which led to initial improvement. However, 60 days later, she relapsed with widespread weakness, and her condition was reclassified as acute-onset CIDP (A-CIDP). This case illustrates the challenge of distinguishing ICI-related AIDP from A-CIDP and the importance of accurate, early diagnosis and treatment. A review of the Literature found 51 AIDP and 10 CIDP cases related to ICIs. Symptoms commonly included weakness, paresthesia, and gait instability, with electromyography and nerve conduction studies often showing demyelinating patterns. Most patients were treated with steroids or IVIg, with significant recovery, though some AIDP cases relapsed or progressed, resembling A-CIDP. This highlights the risk of misdiagnosis in patients with ICI-related AIDP/CIDP. This case underscores the complexities of diagnosing ICI-related neuropathies, especially A-CIDP. Early cessation of ICI therapy and prompt immunosuppressive treatment are essential to prevent long-term disability.