True about polycythemia rubra vera is all except –
**Core Concept**
Polycythemia rubra vera (PRV) is a myeloproliferative neoplasm characterized by the excessive production of red blood cells, white blood cells, and platelets. The underlying pathophysiology involves a mutation in the JAK2 gene, which leads to the activation of the JAK-STAT signaling pathway, promoting the proliferation of hematopoietic cells.
**Why the Correct Answer is Right**
The correct answer is related to the characteristic features of PRV. PRV is indeed associated with a high red blood cell mass, leading to symptoms such as headaches, dizziness, and visual disturbances due to increased viscosity of the blood. The JAK2 mutation is a hallmark of PRV, accounting for approximately 95% of cases. Additionally, PRV is typically a chronic and progressive condition, with an increased risk of thrombotic complications.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because PRV is not typically associated with a decrease in red blood cell mass. In fact, the hallmark of PRV is an increase in red blood cell mass.
**Option B:** This option is incorrect because PRV is not typically associated with a decrease in platelet count. In fact, PRV is often characterized by an increase in platelet count.
**Option C:** This option is incorrect because PRV is not typically associated with a decrease in white blood cell count. In fact, PRV is often characterized by an increase in white blood cell count.
**Clinical Pearl / High-Yield Fact**
A key clinical feature of PRV is the presence of a palpable spleen, which is due to the sequestration of blood cells in the spleen. This is a high-yield fact for exam purposes, as it is a common finding in patients with PRV.
**Correct Answer: D**