The ASCO Post is pleased to present Hematology Expert Review, an ongoing feature that quizzes readers on issues in hematology. In this installment, Drs. Abutalib and Medeiros explore the recently updated World Health Organization (WHO) classification of hematopoietic and lymphoid tissue malignancies, focusing on chronic neutrophilic leukemia. For each quiz question that follows, select the one best answer. The correct answers and accompanying discussions appear below.

Question 1

Which statement about epidemiology and clinical features is correct?

A. Chronic neutrophilic leukemia (CNL) is primarily a disease of younger (age < 60 years) adults.

B. Absence of BCR-ABL1 is not a prerequisite to the diagnosis of CNL.

C. In addition to splenomegaly, bleeding from mucocutaneous surfaces or the gastrointestinal tract is reported in about 25% of CNL cases.

Question 2

Which statement about microscopy is correct?

A. Segmented neutrophils plus banded neutrophils constitute ≥ 80% of the total white blood cells.

B. Peripheral blood smear examination for monocyte count must be < 5 × 109/L.

C. Peripheral blood white blood cell count is ≥ 50 × 109/L.

Question 3

Which statement about genetic profiling is correct?

A. There is no Philadelphia chromosome or BCR-ABL1 fusion in CNL.

B. CSF3R mutation must be absent to diagnose CNL.

C. JAK2 V617F can be present in CNL.

Question 4

Which statement about leukemoid reaction, plasma cell neoplasms, and t(15;19)(q13;p13.3) is correct?

A. A leukemoid reaction is not associated with multiple myeloma.

B. To exclude a leukemoid reaction, the WHO diagnostic criteria require demonstration of clonality of myeloid cells in all cases of suspected CNL.

C. Patients with CNL who have t(15;19)(q13;p13.3), may respond to imatinib therapy. ■