A Rare Case of CML Presenting with Isolated Thrombocytosis

Chronic myeloid leukemia (CML) is a hematological malignancy characterized by uncontrolled granulocyte proliferation driven by the BCR-ABL mutation. Typically, CML presents with leukocytosis, anemia, and splenomegaly. 1 Thrombocytopenia or thrombocytosis may also occur, although isolated platelet abnormalities are uncommon as an initial presentation. In this case report, we present a rare case of a woman in her 50s who initially presented with metabolic encephalopathy and isolated thrombocytosis. Despite thorough investigation for essential thrombocytosis, looking for the most common mutations in ET, such as JAK2 or calreticulin 2, the etiology of her thrombocytosis remained unexplained. It was only upon the subsequent development of leukocytosis and anemia that further investigation led to the diagnosis of CML.