Reticulated ulcers on the bilateral legs

The present case is of a 79-year-old woman with metastatic cholangiocarcinoma who developed painful, reticulated lower extremity ulcers shortly after initiating pemigatinib therapy. Clinical, laboratory, and imaging findings supported the diagnosis of iatrogenic calciphylaxis, a rare but potentially life-threatening adverse effect of fibroblast growth factor receptor (FGFR) inhibitors. Prompt recognition and discontinuation of pemigatinib along with initiation of intravenous sodium thiosulfate and supportive wound care led to significant clinical improvement and normalization of phosphate levels. Given the increasing use of FGFR inhibitors and the rarity of this cutaneous complication, we believe this case is educational and timely.