Setting: office
CC: “I’m itchy and my hands hurt!”
VS: BP: 145/88 mm Hg; P: 88 beats/minute; T: 98°F; R: 23 breaths/minute
HPI: A 45-year-old man comes to the office with generalized pruritus that is clearly worse after taking a bath. He is also having difficulty breathing. He has been to his local ED twice for the same problems. He was sent home because his pulse oximeter level, arterial blood gas (ABG) test, and chest x-ray were all normal.
PMHX:
Peptic ulcer
Medications:
Diphenhydramine
PE:
General: flushed, red face with plethora
Chest: clear to auscultation
Abdomen: enlarged spleen palpable
Extremities: nontender, red painful hands (erythromelalgia)
Initial Orders:
CBC
Oximeter
Chest x-ray
Borderline elevations in blood pressure (BP) have no meaning in a patient who is distressed for any reason.
This case is a good example of how the setting in which the patient is encountered makes a big difference in the diagnostic approach. If this person were in the ED, you would end up doing an urgent ABG, chest x-ray, and CT. If the office, the diagnostic pathway is much slower.
As the clock is moved forward, the patient continues to have an extremely uncomfortable generalized itching, especially after a warm shower.
Reports:
Oximeter 97% on room air
CBC:
Hematocrit 64%; MCV 74 fL; RBCs 6.5 × 106 cells/μL (increased)
White blood cells (WBCs): 18,000/μL
Platelets: 850,000/μL
Chest x-ray: normal
Routine Findings in Polycythemia Vera
• High vitamin B12 level
• High leukocyte alkaline phosphatase (LAP)
Increased RBC count with small MCV
• Polycythemia vera
• Hypoxia
• Thalassemia
Pruritus
• Histamine releases from basophils.
• Warmth releases it.
High Hematocrit Level + Low MCV Level – Hypoxia = Polycythemia Vera
The patient is scheduled to undergo phlebotomy because of shortness of breath.
Janus kinase 2 (JAK2) mutation is 95% sensitive for polycythemia vera.
Low Erythropoietin + High Hematocrit = Polycythemia Vera
What is the most common cause of death in polycythemia vera?
a. Bleeding
b. Thrombosis
c. Transformation to acute leukemia
d. Transformation to myelofibrosis
Answer b. Thrombosis
Blood vessels get clogged up with the increased hematocrit increasing the viscosity of the blood. Large vessel thrombosis such as deep venous thrombosis (DVT), pulmonary embolus (PE), and Budd-Chiari syndrome can kill the patient. The idea is to do phlebotomy to remove the extra RBCs before the vessels clot off.
• Ulcers are part of polycythemia vera.
• Histamine from basophils stimulates extra acid.
After phlebotomy, the patient feels much better. This is the mainstay of therapy. Radioactive phosphorus (P-32) is no longer used. Hydroxyurea is not necessary.
Decreasing blood viscosity increases blood flow.
Over the next 12 to 24 months, the patient is well maintained on regular phlebotomy. The hematocrit decreases and shortness of breath resolves. Pruritus is controlled.
What is the most likely long-term transformation?
a. Acute leukemia
b. Myelofibrosis
c. Myeloma
d. Myelodysplastic syndrome
Answer b. Myelofibrosis
Myelofibrosis can develop from polycythemia vera. You will recognize it when you see teardrop-shaped cells and nucleated RBCs appearing on the peripheral blood smear. Treat myelofibrosis with lenalidomide.
Lenalidomide
• Inhibits TNF
The patient is well maintained on intermittent phlebotomy. The redness of the hands (erythromelalgia) resolves. Splenomegaly from the polycythemia vera persists.