N-Hydroxyurea

BACKGROUND: 'Hydroxyurea-induced Squamous Dysplasia' (HISD) is a cutaneous side-effect related to chronic oral treatment with Hydroxyurea. Ingenol mebutate gel is a topical drug approved for the treatment of multiple, non-hypertrophic actinic keratoses (AK) localized within a limited cancerization field. Since HISD may be considered as a drug-induced variant of classic AK, ingenol mebutate is likely to have therapeutic effects.

Myeloproliferative disorders are a rare cause of focal segmental glomerulosclerosis (FSGS), although the mechanism is unclear. Hydroxyurea is commonly used in these disorders for its cytoreductive properties; however, the effect of this treatment on proteinuria or kidney function remains unclear in cases of myeloproliferative disorder-associated FSGS. We describe the clinical course of a patient with polycythemia vera and nephrotic-range proteinuria, demonstrated to have FSGS on biopsy. The patient had a distant history of granulomatosis with polyangiitis (Wegener's), for which he routinely had his kidney function and proteinuria measured, allowing for early detection of nephrotic syndrome soon after being diagnosed with polycythemia vera. Treatment with hydroxyurea resulted in rapid improvement in proteinuria that correlated with a decrease in hematocrit. This response was replicated 2 additional times when the patient was taken off and then restarted on hydroxyurea therapy.