Approach to Nonmalignant Leukopenia and Leukocytosis

Question · easy

A 32-year-old woman has a routine complete blood count obtained during a wellness visit that shows a leukocyte count of 3800/µL, slightly below the laboratory reference range. She feels well, takes no medications, and her physical examination is unremarkable. Which of the following best explains this result?

A single low leukocyte count below the reference range is diagnostic of early bone marrow failure Reference ranges are set at the mean ±4 SD, so any out-of-range value indicates pathology Reference ranges span the mean ±2 SD, so about 2.5% of healthy people fall outside the range by chance alone Isolated leukopenia in an asymptomatic adult mandates immediate measurement of immunoglobulin levels

Question · medium

A 28-year-old Black man is found to have an absolute neutrophil count (ANC) of 1200/µL on a routine complete blood count. He has never had unusual or recurrent infections, takes no medications, and feels well. Review of prior records shows ANCs between 1000 and 1500/µL for several years. Which of the following is the most appropriate interpretation and management?

This most likely represents Duffy-null–associated neutrophil count; no treatment is needed This pattern indicates autoimmune neutropenia and warrants immunosuppressive therapy This requires urgent bone marrow biopsy to exclude a myelodysplastic syndrome Prophylactic G-CSF should be started to prevent future infections

Question · hard

A 62-year-old woman presents with fever and painful oral ulcerations. Eight weeks ago she was started on methimazole for hyperthyroidism. Her absolute neutrophil count is 200/µL. Which of the following is the most appropriate management?

Stop methimazole and begin long-term prophylactic G-CSF because drug-induced neutropenia is usually irreversible Immediately stop methimazole and treat any infection; the count usually recovers within 1 to 3 weeks, and G-CSF may be considered given the active infection Continue methimazole and schedule urgent splenectomy for neutrophil sequestration Continue methimazole at a reduced dose and add lithium to stimulate neutrophil production

Question · medium

A 67-year-old man has an incidental absolute lymphocyte count of 5200/µL on routine blood work. He is asymptomatic and has no lymphadenopathy or hepatosplenomegaly. Flow cytometry identifies a monoclonal B-cell population of 3200/µL; hemoglobin and platelet counts are normal. What is the most appropriate management?

Perform urgent bone marrow biopsy to stage a lymphoproliferative malignancy No intervention is required; monitor periodically for signs of progression Start rituximab to eradicate the clone before it progresses Begin chemoimmunotherapy now because a monoclonal B-cell clone confirms chronic lymphocytic leukemia