Essential Thrombocythemia: The Dermatologic Point of View.

Essential thrombocythemia (ET) is a myeloproliferative neoplasm characterized by an increase in blood platelets and dominated by a predisposition to vascular events. Cutaneous manifestations can complicate its course. itching has been the most common symptom reported; however, the percentage has ranged from 3% to 46%, depending on the survey. Erythromelalgia is found in 6% of cases, and livedo reticularis, minor bleeding, acrocyanosis, and Raynaud's phenomenon are rare manifestations. It is important to recognize and treat these events, because they can affect patients' quality of life and could worsen the prognosis. In addition to skin involvement as a possible sign of ET, the treatment of ET can be associated with cutaneous complications. Hydroxycarbamide, interferon-alfa, and anagrelide can induce different skin lesions. Hydroxycarbamide has been associated with major complications, including painful leg ulcers and actinic keratoses. Minor events include alopecia and hyperpigmentation. Xerosis, pruritus, and photosensitivity are some of the complications reported by patients treated with interferon-alfa. Anagrelide has proved to be associated with fewer dermatologic effects, only detected in single cases. Knowledge of the ET cutaneous manifestations, together with the clinical examination findings, can result in an earlier diagnosis and the start of effective treatment.