P ruritus is a characteristic and often debilitating clinical manifestation reported by about 50% of patients with polycythemia vera (PV). The exact pathophysiology of PV-associated pruritus is poorly understood. The itch sensation may arise from a central phenomenon without skin itch receptor involvement, as is seen in opioid-induced pruritus, or peripherally via unmyelinated C fibers. Various interventions have been used with mixed results for symptom management in this patient population.1
Selective serotonin reuptake inhibitors (SSRIs), such as paroxetine and fluoxetine, have historically demonstrated some efficacy in treating PV-associated pruritus.2 Alongside SSRIs, phlebotomy, antihistamines, phototherapy, interferon a, and myelosuppressive medications also comprise the various current treatment options. In addition to lacking efficacy, antihistamines can cause somnolence, constipation, and xerostomia.3,4 Phlebotomy and cytoreductive therapy are often effective in controlling erythrocytosis but fail to alleviate the disabling pruritus.1,5,6 More recently, suboptimal symptom alleviation has prompted the discovery of agents that target the mammalian target of rapamycin (mTOR) and Janus kinase 2 (Jak2) pathways.1
Naltrexone is an opioid antagonist shown to suppress pruritus in various dermatologic pathologies involving histamine-independent pathways.3,7,8 A systematic search strategy identified 34 studies on PV-associated pruritus, its pathophysiology and interventions, and naltrexone as a therapeutic agent. Only 1 study in the literature has described the use of naltrexone for uremic and cholestatic pruritus.9 We describe the successful use of naltrexone monotherapy for the treatment of pruritus in a patient with PV.
A 40-year-old man with Jak2-positive PV treated with ruxolitinib presented to the outpatient Michael E. DeBakey Veterans Affairs Medical Center Supportive Care Clinic in Houston, Texas, for severe refractory pruritus. Wheals manifested in pruritic regions of the patient’s skin without gross excoriations or erythema. Pruritus reportedly began diffusely across the posterior torso. Through the rapid progression of an episode lasting 30 to 45 minutes, the lesions and pruritus would spread to the anterior torso, extend to the upper extremities bilaterally, and finally descend to the lower extremities bilaterally. A persistent sensation of heat or warmth on the patient’s skin was present, and periodically, this would culminate in a burning sensation comparable to “lying flat on one’s back directly on a hornet’s nest…[followed by] a million stings” that was inconsistent with erythromelalgia given the absence of erythema. The intensity of the pruritic episodes was subjectively also described as “enough to make [him] want to jump off the roof of a building…[causing] moments of deep, deep frustration…[and] the worst of all the symptoms one may encounter because of [PV].”