Hydroxyurea-associated digital gangrene: a case report and narrative review of reported cases and emerging pathophysiology.

backgroundHydroxyurea (HU) is a first-line oral cytoreductive agent for selected patients with myeloproliferative neoplasms (MPNs), including polycythemia vera (PV), due to its efficacy and tolerability. Although cutaneous ulceration is a recognized complication of long-term HU exposure, HU-associated digital gangrene is rare, and upper-extremity involvement in PV has not previously been reported. CASE PRESENTATION: We describe the first case of HU-associated digital gangrene in a patient with PV. A 72-year-old man with well-controlled Janus kinase 2 (JAK2)-positive PV, treated with HU for more than a decade, developed painless dry gangrene of the right index and middle fingers. Vascular imaging showed no significant arterial occlusion or embolic source. Hematologic parameters remained within target ranges, and the workup for autoimmune disease, infection, and hypercoagulability was unremarkable. HU was discontinued, and the ischemia stabilized without surgical intervention. With no alternative etiology identified, delayed HU-associated vasculopathy was suspected.

conclusionsOur literature review identified three previously reported cases of HU-associated digital gangrene, though limited to the lower extremities - two in chronic myeloid leukemia (CML) and one in sickle cell disease (SCD). In each case, gangrene developed after prolonged HU exposure, alternative etiologies were not substantiated, and stabilization or clinical improvement followed HU withdrawal. The present case aligns with this pattern while extending the reported phenotype to well-controlled PV and upper-extremity digits. Given the small number of reported cases, the pathophysiology remains incompletely defined and is largely extrapolated from studies of more frequently described HU-associated ulceration, histopathologic reports of HU-related tissue injury, and in vitro studies of HU effects on endothelial and circulating cells. Plausible mechanisms include cumulative endothelial injury, localized thrombo-occlusive microvascular dysfunction, impaired vascular and cutaneous repair, and interaction with PV-related microvascular susceptibility. Clinicians should include HU-associated vasculopathy in the differential diagnosis of otherwise unexplained digital ischemia, as prompt drug cessation may limit progression and improve digit salvage.