Pembrolizumab-induced myelitis in stage 4 renal clear cell carcinoma: a case report

Pembrolizumab, an immune checkpoint inhibitor targeting the programmed cell death 1 (PD-1) protein, is widely used for renal cell carcinoma but rarely causes central nervous system adverse events such as myelitis. A 58-year-old woman with stage IV renal clear cell carcinoma developed radiating hip pain, paresthesia, hypoesthesia (T10 and below), constipation, urinary retention, and sudden right-eye blurred vision one month after her sixth cycle of pembrolizumab and lenvatinib. Neurologic examination revealed asymmetrical inferior paraparesis, upper motor neuron signs, and right eye papilledema. MRI demonstrated patchy hyperintensity on C2-C6 and T2-T5, supportive of myelitis. Intravenous methylprednisolone was initiated, leading to pain relief and motor improvement. This is the first reported case of pembrolizumab-induced myelitis in Indonesia, emphasizing the importance of early recognition and corticosteroid therapy for optimal recovery.