In acute leukemias, which are rapidly progressing cancers of the blood and bone marrow, a low platelet count is typically observed, rather than a high one. However, elevated platelet counts can occur in chronic leukemias (especially slow-progressing types like chronic myeloid leukemia) and in certain conditions known as myeloproliferative neoplasms, which involve uncontrolled cell production by the bone marrow. Additionally, high platelet counts can be seen in solid organ cancers such as those of the lung, liver, or stomach.