Elevated Blood Counts (Case 26)

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Chapter 33
Elevated Blood Counts (Case 26)

Marc J. Kahn MD, MBA

Case: A 43-year-old healthy woman presents with upper respiratory symptoms characterized by rhinorrhea, a dry cough, and a headache over a period of 3 days. She presented to her primary-care provider, who diagnosed a viral infection; she was told to drink fluids and take acetaminophen as needed, and was given a decongestant. Two days after her visit, she was called by her physician because the complete blood count (CBC) that had been ordered was abnormal, revealing a white blood cell (WBC) count of 14,600/µL, a hemoglobin of 16.7 g/dL, and a platelet count of 1,432,000/µL. The WBC count differential revealed 80% polymorphonuclear cells, 12% lymphocytes, 5% monocytes, 2% eosinophils, and 1% basophils. On further questioning, she reports some menorrhagia but is otherwise completely asymptomatic. She is very worried that she may have leukemia.

Differential Diagnosis

Polycythemia vera (PV)

Essential thrombocytosis (ET)

Chronic myelogenous leukemia (CML)

 

Speaking Intelligently

Whenever a patient is found to have an abnormal CBC, I always review a peripheral blood smear as the next step. Review of the smear is quick and inexpensive, and can greatly help to narrow a differential diagnosis and to plan further diagnostic tests. It is important to educate the patient that in the absence of immature blood cells, acute leukemia is highly unlikely. Because the patient will be referred to a specialist, it is important that the patient understands your reasoning. This is especially important if the patient is referred to a hematologist/medical oncologist in a cancer center.

PATIENT CARE

Clinical Thinking

• In a patient with elevated blood counts, especially an elevated WBC count, it is important to distinguish a problem with cellular differentiation, such as acute leukemia, from a problem with cellular proliferation, such as the myeloproliferative disorders (MPDs).

• The peripheral blood smear and WBC differential count are helpful in the case presented, because no immature cells are identified. In this case, acute leukemia is extremely unlikely, and the patient is more likely to have an MPD.

• The MPDs can be roughly divided by the cellular element that is increased: ET (platelets increased), PV (red cells increased), and CML (granulocytes increased).

• Agnogenic myeloid metaplasia (AMM) (fibrous tissue increased in the marrow) is also included as an MPD, but unlike the other three disorders, patients usually present with pancytopenia due to marrow replacement with fibrous tissue.

• Although distinctions by cell type are made, in fact, there is great overlap between the MPDs, and most often an individual patient may present with increases in more than one cellular element.

History

• Typically, patients with MPDs are asymptomatic, and abnormalities in the CBC are detected incidentally on routine blood tests.

• Because splenomegaly can occur in patients with CML and other MPDs, patients may complain of early satiety because the enlarged spleen compresses the stomach.

• Patients with ET may complain of erythromelalgia, which is burning and redness in the palms and soles.

• Patients with ET may additionally have problems with either bleeding or thrombosis.

• Patients with PV may complain of pruritus or headache, and may also present with thrombosis.

Physical Examination

• The physical examination may be normal in patients with MPDs.

• Splenomegaly is found in most patients with CML and is also found occasionally in patients with PV and ET.

• Because the MPDs increase the risk for thrombosis, careful examination of the lower extremities is important to look for evidence of arterial or venous insufficiency.

• Easy bruisability may be a feature of ET or PV.

Tests for Consideration

Nucleic acid amplification tests such as polymerase chain reaction (PCR) of peripheral blood for the BCR/ABL transcript, found in patients with the 9;22 translocation (Philadelphia chromosome), are diagnostic of CML.

$315

Bone marrow biopsy and aspirate to look at marrow cellular elements: These can also be used to detect the Philadelphia chromosome [t(9;22)] cytogenetically or by fluorescence in situ hybridization (FISH).

$500

Assay for the JAK2 V617F mutation, found in most patients with PV and half of the patients with ET.

$375

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Polycythemia Vera