Unexplained leukocytosis in an adult

Tural Abdullayev

History

Patient presentation

• 50 year old man• 2 month history of fatigue and early satiety• No evidence of acute or chronic infections or

inflammatory conditions that might lead to reactive granulocytosis and thrombocytosis.

Complete Blood Count• WBC – 75,000/µL (normal range: 4,000-10,000/µL) • Hgb – 14 g/dL (normal range: 14-16.5 g/dL)• Hct – 42% (normal range: 42%-50%)• MCV – 88 fl (normal range: 80-96 fl)• Platelets – 550,000/µL (normal range: 150,000-400,000/µL)

Differential• Segmented neutrophils (granulocytes) –33,000/µL (normal range: 1,800-

7,000/µL) • Bands – 1,500/µL (normal range: 0-700/µL)• Metamyelocytes –11,000/µL (normal: 0)• Myelocytes – 7500/µL (normal: 0)• Basophils – 3,750/µL (normal range: 0-200/µL)• Lymphocytes – 3,000/µL (normal range 1,000-4,800/µL)• Monocytes – 750/µL (normal range 0-800/µL)

Complete Blood Count

• Based on CBC results:1. Leukocytosis – ↑ WBC2. Granulocytosis – ↑ neutrophils3. Thrombocytosis – ↑ platelets4. No evidence of Anemia – Normal Hb, Hct, MCV 5. Basophilia – ↑ basophils

Physical Examination

Physical Examination• Afebrile

• Head, ears, eyes, nose, throat– Anicteric (absence of jaundice)

• No lymphadenopathy

• Lungs – Clear – No pulmonary signs of infection or malignancy

• Heart– No murmurs

• Abdomen– No signs of ascites– Liver edge is not palpable– Spleen edge is palpable 4 cm below the left costal margin (Slenomegaly)

• Skin– No petechiae– No ecchymoses– No spider angiomata

• Neurologic exam– Normal

Findings that help to rule out reactive causes of neutrophilia and thrombocytosis

1. Afebrile – Indicates that there is no evidence of

inflammation2. No lymphadenopathy

Splenomegaly• Possible causes

1. Endothelial or immune system hyperplasia from infections, immune disorders or chronic hemolysis2. Infections associated with splenomegaly:

Bacterial endocarditis Malaria Schistosomiasis TB

3. Immune disorders associated with splenomegaly: SLE RA

4. Chronic hemolysis associated with splenomegaly: Hereditary: thalassemias, spherocytosis, hemoglobin SC disease (note that young children with sickle cell

disease will have splenomegaly, but recurrent infarctions ultimately result in necrosis, fibrosis and functional asplenia)

Acquired: autoimmune hemolytic anemia

5. Altered splenic blood flow: cirrhosis; splenic, hepatic or portal vein thrombosis6. Primary or metastatic malignancies: lymphoma, Hodgkin's disease, chronic lymphocytic leukemia7. As a result of extramedullary hematopoiesis (myeloproliferative disorders)8. Infiltration: amyloid, Gaucher's disease

Laboratory Data• Laboratory and diagnostic studies would be helpful in making a diagnosis

1. Evaluation of peripheral smear Help to differentiate CML from leukocytosis of other etiology In case of CML, a complete spectrum of myeloid cells is seen in the peripheral blood. The

levels of neutrophils and myelocytes exceed those of blast cells and promyelocytes

2. Chest X-ray In case of suspicion of reactive thrombocytosis and granulocytosis secondary to infection

or to a solid tumor

3. Iron studies In case of suspicion of Polycythemia vera

4. Serial stool testing for occult blood – Guaiac tests In case of suspicion of reactive thrombocytosis and granulocytosis secondary to a solid

tumor

5. Uric acid In CML serum uric acid is usually raised

Differential Diagnosis

Differential diagnosis

1. Acute myelogenous leukemia 2. Polycythemia vera3. Essential thrombocythemia4. Chronic myelogenous leukemia5. Chronic myelomonocytic leukemia6. Reactive thrombocytosis and granulocytosis

secondary to infection7. Reactive thrombocytosis and granulocytosis

secondary to a solid tumor

Acute myelogenous leukemia (AML)

• INCORRECT– Although AML frequently presents with an elevated total

WBC count, the white blood cells are immature blast forms. This is due to maturation arrest, which is part of the pathophysiology of acute leukemia.

– Additionally, in acute leukemia, mature white blood cells such as bands and neutrophils (granulocytes) are decreased

– Patients with acute leukemia usually have thrombocytopenia (a decreased platelet count)

– Patients with acute leukemia are typically acutely ill with fever, anemia, and signs of bleeding.

Polycythemia vera

• UNLIKELY– Polycythemia vera may be associated with the constitutional symptoms

described as well as with splenomegaly, granulocytosis, basophilia and thrombocytosis.

– However, one of its defining features, an elevated Hct, is not present in this patient.

– Sometimes, with profound iron deficiency, the hematocrit may not be elevated. Iron studies would indicate iron deficiency (low serum iron, elevated total iron binding capacity) and the MCV would be decreased. This patient has normal iron studies and a normal MCV.

– Mutations in JAK2, a tyrosine kinase involved in the physiology of the bone marrow response to erythropoietin and in cell proliferation, have recently been identified in more than 95% of patients with polycythemia vera (but not in patients with secondary erythrocytosis).

Essential thrombocythemia

• Unlikely– The prominent feature of essential thrombocythemia is

thrombocytosis– Granulocytosis and splenomegaly are seen in about 50% of

patients, but there is not typically a marked left shift in the granulocyte differential, as seen in this patient

– Basophils may be mildly increased– Mutations in JAK2, a tyrosine kinase involved in the

physiology of the bone marrow response to erythropoietin and in cell proliferation, have been identified in about 50% of patients with essential thrombocythemia.

Chronic myelogenous leukemia

• Correct! This is the most likely diagnosis– CML is characterized by granulocytosis with a left

shift, basophilia, thrombocytosis and splenomegaly– Increasingly patients are being diagnosed while

asymptomatic, on the basis of an elevated WBC count detected on routine screening

– However, symptoms including fatigue and night sweats may be seen, secondary to the increased metabolic state

– Early satiety may occur as a result of splenomegaly.

Chronic myelomonocytic leukemia• Unlikely

– Patients with chronic myelomonocytic leukemia (CMMoL) can have features of both myelodysplastic and myeloproliferative disorders

– Although patients with CMMoL may have leukocytosis and splenomegaly, they are usually older at diagnosis (median age 73) than patients with the classic myeloproliferative disorders, and they are often symptomatic (weight loss, night sweats)

– By the World Health Organization definition, patients with CMMoL have a peripheral blood monocytosis (>1,000/µL)

– In contrast to classic myeloproliferative disorders, however, patients with CMMoL usually have anemia and thrombocytopenia, secondary to dysplastic and ineffective hematopoiesis.

Reactive thrombocytosis and granulocytosis secondary to infection

• Unlikely– The absence of fever, CXR abnormalities (Tb), and

cardiac murmur (endocarditis) makes infection unlikely

– Patients with reactive thrombocytosis and granulocytosis secondary to infection would likely be more ill appearing.

Reactive thrombocytosis and granulocytosis secondary to a solid tumor

• Unlikely– The absence of weight loss, cachexia, CXR

abnormalities, gastrointestinal bleeding, and lymphadenopathy makes a solid tumor unlikely.

Diagnostic tests to perform to make a diagnosis

Bone marrow aspiration and biopsy

– Done to evaluate the karyotype as well as cellularity (usually increased) and extend of myelofibrosis

– During accelerated phase of disease melofibrosis may develop and sideroblasts may be seen on microscopy

Bone marrow quantitative polymerase chain reaction (qPCR) analysis for BCR-ABL gene

• Presence of the BCR ABL1 gene fusion by RT PCR analysis and ‐ ‐in 98% of cases Ph chromosome on cytogenetic analysis

JAK2 mutation analysis• The normal JAK2 gene, located on the short arm of chromosome 9• Is a kinase involved in intracellular signaling following exposure of

hematopoietic cells to cytokines (hematopoietic growth factors such as erythropoietin, thrombopoietin and granulocyte-macrophage colony stimulating factor)

• One common mutation in this gene is the result of a single amino acid substitution of valine to phenylalanine at position 617 (JAK2 V617F).

• The mutated gene may be involved in the pathogenesis of myeloproliferative disorders by conferring a proliferative and survival advantage to hematopoietic cells and by making these cells hypersensitive to the effect of cytokines

Flow cytometry of peripheral blood• Leucocytosis is the main feature and may reach levels greater

than 200× 109 /L (Fig. 14.2). A complete spectrum of myeloid cells is seen in the peripheral blood. The levels of neutrophils and myelocytes exceed those of blast cells and promyelocytes

Clinical features of the myeloproliferative disorders and reactive granulocytosis and

thrombocytosisDisorders RBC WBC PLTS Bone

Marrow Fibrosis

Splenomegaly

JAK2 mutation

Ph1

Polycythemia vera Granulocytosis+/- + 95% -

Essential thrombocythemia

NI Granulocytosis +/- + 50% -

CML NI Granulocytosis

+/- + - +

Primary myelofibrosis

Neutropenia +++ ++ 50% -

CMMoL Monocytosis+/- + - -

Reactive granulocytosis

NI Granulocytosis NI/ - - - -

Reactive thrombocytosis

NI NI/Granulocytosis - - - -

Pathophysiology

Pathogenesis of CML• The disease accounts for around 15% of leukaemias and may occur at any

age• The diagnosis of CML is rarely difficult and is assisted by the characteristic

presence of the Philadelphia (Ph) chromosome• Philadelphia (Ph) chromosome results from the t(9;22) (q34;q11)

translocation between chromosomes 9 and 22, as a result of which part of the oncogene ABL1 is moved to the BCR gene on chromosome 22 and part of chromosome 22 moves to chromosome 9.

Pathogenesis of CML• The abnormal chromosome 22 is the Ph chromosome• In the Ph translocation 5 exons of BCR are fused to the 3 exons of ABL1′ ′• The resulting chimeric BCR ABL1 gene codes for a fusion protein of size ‐

210kDa (p210)• This has tyrosine kinase activity in excess of the normal 145 kDa ABL1 product‐• The Ph translocation is also seen in a minority of cases of acute lymphoblastic

leukaemia (ALL) and in some of these the breakpoint in BCR occurs in the same region as in CML

• However, in other cases the breakpoint in BCR is further upstream, in the intron between the first and second exons, leaving only the first BCR exon intact

• This chimeric BCR ABL1 gene is expressed as a p190 protein which, like p210, ‐has enhanced tyrosine kinase activity

Prognosis and Clinical course

Prognosis

• Attempts have been made to stage CML at presentation in order to predict prognosis. The most frequently used is the Sokal score, which takes account of age, blast cell percentage, spleen size and platelet count. However the rate of response to a tyrosine kinase inhibitor is now a more useful measure

Sokal score• Age• Spleen size ( cm below costal

margin )• Platelet count• Platelet count (x 109/L)• Peripheral blood blasts (% of

leukocytes)• Peripheral blood eosinophils (%

of leukocytes)• Peripheral blood basophils (% of

leukocytes)

Treatment• Tyrosine kinase inhibitors

1. Imatinib2. Nilotinib3. Dasatinib4. Bosutinib5. Ponatinib

• Allogenic stem cell transplantation – for patients reflactory to frontline therapy

• Splenic radiation – in reflactorycases or in terminal patients with marked splenomegaly

• Splenectomy – when irradiation/chemotherapy aren’t effective

Imatinib + Chemotherapy• Stage 1

– Imatinib 400mg x 1/d– If no effect : interferon–α 3 mln IU x 3/week + hydroxyurea 1 – 2g x

1/d• Stage 2

– Imatinib 600 – 800mg x 1/d– Or more aggressive chemotherapy with : Daunorubicin +

Cytarabine– For older patients: less aggressive chemotherapy with hyproxyurea

+ interferon–α • Stage 3

– Treated like acute leukemia