What symptom is classic for Polycythemia vera?

Polycythemia vera is a myeloproliferative neoplasm characterized by an overproduction of red blood cells. One of the classic symptoms associated with this condition is pruritus, or severe itching, particularly after exposure to water such as during a bath or shower. This symptom is thought to arise due to increased levels of histamine and other substances released from mast cells, which are more prevalent in individuals with polycythemia vera.

While fatigue after exercise, joint pain, and frequent infections can occur in patients with various hematological conditions or other diseases, they are not specific symptoms of polycythemia vera. Fatigue may result from the increased blood viscosity and its impact on circulation, joint pain could relate to hyperuricemia, and frequent infections may arise from other underlying issues, but none match the distinctive nature of post-bathing pruritus in polycythemia vera. Thus, the presence of skin itching after bathing is a hallmark feature that highlights the condition.