In this type of MPN, the older population is predominantly affected, but there is a frequent occurrence in young women described in some series. The incidence in males and females is about equal. Many patients with this type of MPN are asymptomatic; the major clinical manifestations are usually related to thrombosis. The thrombosis can be in the arterial or venous system, but arterial is more common. Small vessels are affected more often than larger vessels. The neurological and distal extremities are most commonly affected. Neurological manifestations of this include headache, paresthesias, and transient ischemic attacks, which may progress to definitive cerebral infarcts.
Small vessel involvement include microvascular events involving fingers and toes. Digital pain, increased by warmth, is seen, as well as gangrene in digits. Erythromelalgia -- redness, duskiness, and burning pain in extremities -- is a common symptoms, and can be dramatically relieved with aspirin.
Essential Thrombocythemia (ET)