Specific fibroblast growth factor receptor (FGFR) inhibitors have been developed to treat malignancies harboring fusions or rearrangements in FGFR2 or FGFR3. Here, we report a case of calciphylaxis cutis in association with FGFR inhibitor therapy in a patient with FGFR2 rearranged cholangiocarcinoma. Although calciphylaxis cutis typically arises in the setting of hyperphosphatemia and end-stage renal disease, this patient had preserved renal function, normal serum calcium, and only modestly elevated serum phosphorus levels, which is similar to other recent reports of calciphylaxis in patients receiving FGFR inhibitor therapy. Calciphylaxis cutis is a possible adverse event observed with FGFR inhibitor therapy, and the mechanism of calciphylaxis cutis in association with FGFR inhibitor therapy warrants further investigation.

A 51-year-old male presented with a painful ulcer on his glans penis. Histopathological and radiological examination showed extensive microangiopathy and calcification of small and medium-sized arteries and the diagnosis 'calciphylaxis cutis' was made. Calciphylaxis cutis is caused by calcium deposits in small and medium-sized arteries, and most commonly seen in patients with end-stage renal failure and hyperparathyroidism.