A 58-year-old man has hemoglobin 20.5 g/dL, hematocrit 62%, elevated red cell mass, thrombocytosis, and splenomegaly. Erythropoietin level is low. Mutation analysis is most likely to show which finding?

• A JAK2 V617F mutation ✓
• B BCR-ABL1 fusion transcript
• C CALR exon 9 frameshift mutation
• D KIT D816V mutation

Explanation

Polycythemia vera shows panmyelosis with low erythropoietin because erythroid proliferation is EPO-independent. More than 95% of patients carry the JAK2 V617F gain-of-function mutation, which makes the JAK-STAT pathway constitutively active. CALR mutations are found mainly in JAK2-negative essential thrombocythemia and primary myelofibrosis, KIT D816V defines systemic mastocytosis, and BCR-ABL1 defines CML, a separate entity.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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