[Coexistence of essential thrombocythemia and gastric cancer].

A 74-year-old man was admitted because of swelling, pain and ecchymosis in the night lower extremity. A blood analysis revealed that Hb was 11.8g/dl, WBC 37,600/microliters, and platelet count 137.1 x 10(4)/microliters. The NAP value was high. Bone marrow examination disclosed marked megakaryocytic hyperplasia. Chromosomal analysis revealed 47, XY, +9. Hemostatic data were within normal ranges, but the 2nd aggregation of platelet by ADP was diminished. The serum beta-TG was 159, PF-4 56ng/ml, B12 1,100, UB12 BC 1,800pg/ml. Gastric fiberoscopy revealed gastric cancer and CT scan disclosed marked splenomegaly. Essential thrombocythemia (ET) coexisting with gastric cancer was diagnosed based on these examinations. He was treated with anti-platelet agents, busulfan and tegafur uracil, however thromboembolic symptoms suggesting central nervous system and peripheral vascular ischemia and gastrointestinal bleeding occurred. Among diagnostic criteria for ET established by the polycythemia vera study group, there is a category "No known cause for reactive thrombocytosis." The case reported here had gastric cancer which may have contributed to the elevated platelet count, however this case could be diagnosed as ET coexisting with gastric cancer because of the above various clinical signs and laboratory results. Although then are few reports of the coexistence of other malignancies in ET, there may be many more similar cases because of the age preponderance in ET. In order to diagnose ET more precisely, more strict diagnostic criteria are needed.