Differential Diagnosis for Abnormal White Blood Cell Count

The patient presents with a low white blood cell count (WBC) of 2.9, elevated basophils at 3.1, and decreased neutrophils at 1.25. Here's a categorized differential diagnosis:

• Single Most Likely Diagnosis
  • Myeloproliferative Neoplasm (MPN): The elevated basophil count is a key indicator, as basophilia is commonly seen in certain MPNs, such as chronic myeloid leukemia (CML). The low WBC and neutrophil count could be due to bone marrow suppression or replacement by the neoplastic cells.
• Other Likely Diagnoses
  • Viral Infections: Certain viral infections can cause a decrease in WBC and neutrophils, while sometimes increasing basophils. For example, influenza or HIV could lead to such a presentation.
  • Hypersplenism: This condition, often due to splenomegaly from various causes, can lead to sequestration of white blood cells, resulting in low counts in the peripheral blood.
  • Medication-Induced Leukopenia: Various medications can cause a decrease in WBC and neutrophil counts as a side effect.
• Do Not Miss Diagnoses
  • Aplastic Anemia: Although less likely given the elevated basophils, aplastic anemia is a potentially life-threatening condition that requires prompt diagnosis and treatment. It is characterized by bone marrow failure, leading to pancytopenia.
  • Severe Combined Immunodeficiency (SCID): This is a rare but critical condition to consider, especially if the patient has recurrent severe infections. SCID can present with low WBC counts.
• Rare Diagnoses
  • Basophilic Leukemia: A rare form of leukemia characterized by the proliferation of basophilic precursors. It could explain the elevated basophil count but is less common.
  • Mastocytosis: Although primarily known for mast cell proliferation, some forms of mastocytosis can present with elevated basophils. It's a rare condition that could potentially explain the patient's lab results.