Late-Onset Hydroxyurea-Induced Melanonychia and Tongue Hyperpigmentation in a Patient With Polycythemia Vera: A Case Report.

In a rare case, a 70-year-old female with polycythemia vera developed late-onset melanonychia, a seldom-documented side effect of hydroxyurea. Typically, melanonychia emerges within months of treatment, but this case is unique as it occurred four years into therapy. Notably, the patient, with darker skin, also had hyperpigmentation of her hands and tongue. Her history of hydroxyurea-associated ulcers and symptoms worsening with dose adjustment suggested drug involvement. While mucocutaneous hyperpigmentation from hydroxyurea is known, melanonychia and tongue hyperpigmentation are rarely reported, mostly in early treatment. This case highlights the importance of recognizing these side effects, especially in diverse populations and darker skin tones. The diverse skin tones seen in Sub-Saharan Africa add complexity to diagnosing such dermatological conditions, highlighting the need for awareness. Melanonychia can mimic severe conditions such as subungual melanoma, emphasizing the significance of accurate recognition and management without invasive tests. Educating clinicians and patients about these benign drug-related phenomena is essential for precise identification and management. This case contributes to understanding late-onset hydroxyurea-induced melanonychia and tongue hyperpigmentation, enhancing clinical knowledge in diverse populations.