Haematology for MRCPI Part 2

A 63-year-old woman is found to have a haemoglobin of 184 g/L, haematocrit 0.56, white cells 13.2 × 10⁹/L and platelets 520 × 10⁹/L. She reports itching after hot baths and has had a splenic vein thrombosis. Erythropoietin level is low. JAK2 V617F mutation is positive. What is the most appropriate initial management?

1. Observation, since she is asymptomatic apart from pruritus Wrong. She has already had a thrombosis, which is precisely the event that management exists to prevent recurring.
2. Venesection to a target haematocrit below 0.45, plus low-dose aspirin and cytoreduction correct Correct. This is polycythaemia vera with a prior thrombosis, which places her in the high-risk group. Haematocrit control below 0.45 reduces thrombotic events, aspirin reduces microvascular events, and prior thrombosis plus age over 60 is an indication for cytoreductive therapy, usually hydroxycarbamide.
3. Allogeneic stem cell transplantation Wrong at this stage. Transplant is considered for transformation to myelofibrosis or acute leukaemia in selected patients.
4. Venesection alone with no other therapy Insufficient in a high-risk patient. Age over 60 or previous thrombosis mandates cytoreduction alongside venesection.
5. Long-term warfarin as the primary intervention Wrong as primary management. Anticoagulation treats the thrombosis itself, but it does not address the raised haematocrit and cell mass driving further events.

The point: Polycythaemia vera: low erythropoietin plus JAK2 mutation distinguishes it from secondary polycythaemia, where erythropoietin is high. Aquagenic pruritus and unusual-site thrombosis such as splanchnic vein are the classic clues. Target haematocrit below 0.45, aspirin for all, cytoreduce if over 60 or previously thrombosed.

Source: BSH guideline for the diagnosis and management of polycythaemia vera British Society for Haematology · tier 2, specialty society or college