Which condition is associated with thrombocytosis?

• A. DIC
• B. Splenomegaly
• C. Polycythemia vera
• D. Idiopathic thrombocytopenic purpura

Answer: (C)

Thrombocytosis means an elevated platelet count, which often arises from clonal overproduction seen in certain myeloproliferative neoplasms. Polycythemia vera is a classic example where the bone marrow makes more blood cells across lineages, including platelets, leading to thrombocytosis. This disorder is driven by mutations like JAK2 V617F that promote proliferation of erythroid, granulocytic, and megakaryocytic cells, so platelets rise along with red cells.

DIC, by contrast, is a consumption coagulopathy where platelets are typically depleted, so thrombocytosis is not the feature. Idiopathic thrombocytopenic purpura involves autoimmune destruction of platelets, causing low counts. Splenomegaly can accompany various diseases but is not the defining cause of thrombocytosis. Thus, polycythemia vera best fits with thrombocytosis.