Immune-Related Thyroiditis — SCE Dermatology MCQ

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ModerateSkin CancerImmune-Related ThyroiditisSCE Dermatology

A 65-year-old man with melanoma has been on adjuvant Pembrolizumab for 3 months. He develops hypothyroidism with TSH 45 mU/L and free T4 5.2 pmol/L. This is confirmed as immune-related thyroiditis. What is the recommended management?

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Correct answer: B — Continue Pembrolizumab and start Levothyroxine replacement

Immune-related thyroiditis (initially thyrotoxic phase followed by hypothyroid phase) is one of the most common endocrine irAEs of anti-PD-1 therapy, occurring in approximately 5-10% of patients. Unlike other grade 3-4 irAEs, endocrine irAEs (hypothyroidism, hyperthyroidism) are managed with hormone replacement (Levothyroxine for hypothyroidism) WITHOUT stopping the checkpoint inhibitor. The thyroid dysfunction is usually permanent, requiring lifelong Levothyroxine. Pembrolizumab should only be held for severe symptomatic thyroiditis or adrenal crisis. This contrasts with hepatitis, colitis, or pneumonitis where checkpoint inhibitors must be withheld for grade 3+ toxicity.

Reference: NICE NG14 Melanoma; ESMO irAE Management 2022