Erythromelalgia: a cutaneous manifestation of polycythemia vera

A 77-year-old woman presented in March 2025 for diffuse widespread pruritus and palmar erythema with burning pain that onset approximately 4 months prior.She was initially treated with Dupixent, 300 mg subcutaneously every 2 weeks, and antihistamines with a presumed diagnosis of atopic dermatitis.The patient noted her pruritus worsened after a shower and did not fully resolve with prescribed therapies.Despite the widespread pruritus, the patient did not have any other primary lesions suggestive of a papulosquamous or eczematous disorder; the palmar erythema was her only cutaneous manifestation.A review of systems was otherwise negative for other concerning symptoms.Given her refractory symptomatology, additional labs were ordered and demonstrated elevations across myeloid blood cell lines: leukocytes, 13.6 K/uL (reference range, 4.5-10.0);erythrocytes, 6.16 10*6/uL (reference range, 3.5-5.5);hemoglobin, 17.8 g/dL (reference range, 11.0-16.0);hematocrit, 56.6 % (reference range, 32.0-48.0);platelets, 465 K/uL (reference range, 150-400); neutrophils, 9.81 K/uL (reference range, 1.80-8.5);eosinophils, 0.61 K/ uL (reference range, 0.00-0.50);and basophils, 0.24 K/uL (reference range, 0.00-0.20).A physical examination revealed diffuse palmar erythema (Figure 1) without any cutaneous evidence of atopic dermatitis clinically consistent with erythromelalgia.The patient was diagnosed with polycythemia vera and referred to hematology for continued management.Routine phlebotomies resolved her pruritus and erythromelalgia of her hands after two sessions (Figure 2).Polycythemia vera is a chronic myeloproliferative neoplasm indicated by the clonal overproduction of erythrocytes, leukocytes, and platelets [1,2].This cellular overproduction increases the risk of vascular complications, including erythromelalgia.Erythromelalgia is a distinct yet Figure 1: Diffuse and confluent erythema of the bilateral ventral hands.