Differential Diagnosis for a 16-month-old with WBC of 3.5 and Monocyte Percent of 14.3
- Single Most Likely Diagnosis
- Viral infection: A low white blood cell count (leukopenia) with a relatively high monocyte percentage can be seen in various viral infections, which are common in children of this age group. The body's response to viral infections often involves a decrease in the total WBC count, with a possible relative increase in monocytes.
- Other Likely Diagnoses
- Bacterial infection: Although the WBC count is low, some bacterial infections, especially in their early stages or in partially treated cases, might present with leukopenia. The monocyte percentage can be elevated as part of the body's response to infection.
- Nutritional deficiencies: Deficiencies in nutrients like vitamin B12 or folate can lead to changes in blood cell counts, including leukopenia. However, these would typically be accompanied by other signs of deficiency.
- Chronic benign neutropenia of childhood: This condition is characterized by a persistently low neutrophil count but is often asymptomatic and discovered incidentally. It's more common in certain ethnic groups.
- Do Not Miss Diagnoses
- Leukemia/Lymphoma: Although less likely, it's crucial to consider malignancies like leukemia or lymphoma, as they can present with abnormal blood cell counts, including leukopenia. Early detection is vital for effective treatment.
- Severe combined immunodeficiency (SCID): This is a group of rare disorders caused by mutations in different genes involved in the development and function of the immune system. SCID can present with recurrent severe infections and abnormal blood cell counts.
- HIV infection: Vertical transmission (from mother to child) can occur, and HIV infection can lead to a variety of hematologic abnormalities, including leukopenia.
- Rare Diagnoses
- Congenital neutropenias (e.g., Kostmann syndrome): These are rare genetic disorders characterized by severe neutropenia from birth, which can lead to recurrent infections.
- Cyclic neutropenia: A rare condition where neutrophil counts fluctuate, leading to periodic episodes of neutropenia and increased risk of infections.
- Shwachman-Diamond syndrome: A rare genetic disorder that affects the bone marrow, pancreas, and skeleton, leading to cytopenias, including neutropenia.