Oncology Case Challenge: A 46-Year-Old Mother With Severe, Constant Abdominal Pain

Mounika Gangireddy, MD, MBBS

Disclosures

April 13, 2022

Discussion

Thrombocytosis (> 600,000 cells/µL) occurs in about 15%-30% of patients with chronic myeloid leukemia (CML). Approximately 20% of patients present with bleeding complications due to dysfunctional platelets, as in this case. This patient had an atypical presentation of CML with marked thrombocytosis without leukocytosis, which made the diagnosis challenging.

The differential diagnosis of CML includes leukemoid reaction, myeloproliferative disorders, essential thrombocythemia, and polycythemia vera with iron deficiency. Leukemoid reaction presents with an elevated WBC count (< 50 × 109/L), toxic vacuolation, Döhle bodies, and an absence of basophilia.

It is difficult to differentiate myeloproliferative or myelodysplastic syndrome from CML owing to the presence of thrombocytosis, neutrophilia, and splenomegaly in both diseases. Bone marrow biopsy and mutational analysis are helpful in such instances. Patients who have polycythemia vera with severe iron deficiency can exhibit leukocytosis and thrombocytosis. Such patients have normal or increased leukocyte alkaline phosphatase scores with a WBC count < 25 × 109/L and no Philadelphia (Ph) abnormality.

In the patient in this case, other causes of thrombocytosis were excluded by JAK-2V617, exon 12, MPL exon 10, CALR exon 9, and CSF3R exon 14/17 mutation analyses. The results were all negative, thus ruling out myeloproliferative disorders. Chronic lymphocytic leukemia (CLL) is less likely given the left-shifted marrow and normal flow cytometry results. Severe iron deficiency can result in thrombocytosis. However, it does not solely explain the platelet count of over 3 million cells/µL with the presence of Ph chromosome. Quantitative polymerase chain reaction (PCR) testing for percentage of BCR-ABL1/Abl1 was elevated at 66%, with detection of p210 BCR-ABL transcript along with the presence of t(9;22) on the bone marrow sample. These findings confirmed the diagnosis of CML.

CML is a clonal myeloproliferative disorder of pluripotent stem cells. It accounts for about 10%-15% of adult leukemias. The incidence is 1-2 per 100,000, and the prevalence is 5 per 100,000 adults.[1] The 10-year overall survival rates have increased from 20% to 90% with the introduction of tyrosine kinase inhibitors (TKIs).[2]

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