Late-Onset Normotensive Thrombotic Microangiopathy and Pyoderma Gangrenosum Following Nine Years of Sunitinib Therapy: A Case Report

Sunitinib, a tyrosine kinase inhibitor used for metastatic renal cell carcinoma, is associated with various adverse effects. We present the case of a 60-year-old woman who developed biopsy-proven thrombotic microangiopathy and concurrent pyoderma gangrenosum after 9 years of sunitinib therapy. This case is unusual due to the extremely delayed onset of both rare toxicities. Furthermore, the thrombotic microangiopathy presented without hypertension, a typical preceding sign, which made the diagnosis challenging. The patient initially presented with a painful leg ulcer, diagnosed as pyoderma gangrenosum, and was subsequently found to have significant proteinuria and edema. A kidney biopsy confirmed thrombotic microangiopathy. Upon discontinuation of sunitinib, both the proteinuria and the pyoderma gangrenosum lesions improved significantly, confirming a causal relationship. This case represents the longest reported latency period for both sunitinib-induced thrombotic microangiopathy and pyoderma gangrenosum. It underscores the critical need for sustained clinical vigilance for severe, late-onset adverse events at any point throughout long-term sunitinib treatment and demonstrates that clinicians cannot rely solely on hypertension as a predictive marker for thrombotic microangiopathy.