Pembrolizumab-Induced Thyroiditis and Colitis

Pembrolizumab-Induced Thyroiditis and Colitis—Presentation and Resolution on Serial FDG PET/CT: A 58-year-old man with previous melanoma of the left leg underwent whole-body 18F-FDG PET/CT to stage metastatic disease prior to commencing pembrolizumab. Follow-up FDG PET/CT after 3 months of treatment showed partial metabolic response of soft tissue and nodal metastases and diffuse increased thyroid and colonic uptake, suggestive of thyroiditis and colitis. Pembrolizumab was ceased, and a repeat FDG PET/CT scan showed regression of uptake in the thyroid gland and colon, in keeping with resolution of inflammatory change. Immune-related adverse events induced by Immune checkpoint inhibitors, such as pembrolizumab, should be recognized—cessation of treatment often leads to resolution.

Received for publication June 10, 2020; revision accepted August 9, 2020.

Conflicts of interest and sources of funding: none declared.

Correspondence to: Ayah Adel Nawwar, MSc, Cobalt Medical Charity, Linton House, Thirlestaine Rd, Cheltenham GL53 7AS, United Kingdom. E-mail: ayah.nawwwar@doctors.net.uk.

Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.