<unk>  <unk>  or primary<unk>  is a rare hematologic disorder which arises from hematopoietic stem cells that give rise to megakaryocytes which in turn produce platelets (thrombocytes), that are normally involved in blood clotting.<unk>  is characterized by overproduction of platelets in the absence of an underlying disease.<unk>  was first defined by Emil Epstein and Alfred Goedel, two Austrian pathologists, in the year 1934 and was initially called hemorrhagic thrombocythemia. Subsequently,<unk>  was classified as a myeloproliferative disorder along with chronic myelogenous leukemia (CML), polycythemia vera (PV), and chronic idiopathic myelofibrosis (CIMF). The incidence of<unk>  is approximately 0.6-2.5 cases per 100,000 individuals worldwide annually. The prevalence of<unk>  is about 30 for every 100,000 people worldwide. Females are more commonly affected with<unk>  than males. The female to male ratio is approximately 2 to 1. Symptoms of<unk>  include vision disturbances, transient loss of consciousness, chest pain, intense burning pain in hands or feet (erythromelalgia), numbness and tingling of hands and feet, persistent and painful erection of the penis (priapism). Bone marrow biopsy may be helpful in the diagnosis of<unk> , in addition to ruling out other secondary causes of<unk> . The majority of cases of<unk>  only require supportive care. Pharmacologic medical therapies for<unk>  include aspirin therapy for low risk patients and platelet lowering drugs such as (hydroxyurea, interferon-α, and anagrelide) for high risk patients.
Essential thrombocytosis
Polycythemia vera
Thrombotic thrombocytopenic purpura
Basophilia
Idiopathic thrombocytopenic purpura
Heparin-induced thrombocytopenia
Myelofibrosis
Pseudo gray platelet syndrome