Differential Diagnosis for Left Shift with Low Leukocyte Counts and 85% Neutrophils

• Single Most Likely Diagnosis
  • A. Septicemia: This condition is characterized by the presence of bacteria in the blood and can lead to a left shift (an increase in immature white blood cells, such as band neutrophils) in the context of an infection. The body's response to a severe infection can sometimes result in an initial decrease in the total white blood cell count due to the consumption of neutrophils at the site of infection, despite an increased percentage of neutrophils.
• Other Likely Diagnoses
  • B. Leukemia: Certain types of leukemia, especially acute myeloid leukemia (AML), can present with a left shift and abnormal white blood cell counts. However, leukemia typically presents with an elevated white blood cell count, although some cases can have a normal or low count, especially in the early stages or in specific subtypes.
• Do Not Miss Diagnoses
  • A. Septicemia (also listed as the single most likely diagnosis, but included here for emphasis): It's crucial not to miss septicemia due to its high mortality rate if not promptly treated. The presence of a left shift, even with low leukocyte counts, should raise suspicion for septicemia, especially in the context of clinical signs of infection.
  • B. Leukemia: Although leukemia might not always present with the classic high white blood cell count, missing the diagnosis can lead to delayed treatment and poor outcomes.
• Rare Diagnoses
  • D. Pelger–Huët anomaly: This is a rare benign inherited condition characterized by abnormal nuclear morphology of neutrophils. While it can mimic a left shift due to the appearance of the neutrophils, it does not typically present with low leukocyte counts or signs of infection/inflammation.
  • C. Multiple sclerosis: This is an autoimmune disease affecting the central nervous system and is not directly related to the hematological findings described. It would not typically be considered in the differential diagnosis for a left shift with low leukocyte counts and a high percentage of neutrophils.

Justification for each diagnosis is based on the clinical presentation and laboratory findings. The key is to consider conditions that could lead to both a left shift (indicative of an infectious or inflammatory process) and low leukocyte counts (which could be seen in early infection, bone marrow failure, or specific types of leukemia). Septicemia stands out due to its potential for high morbidity and mortality, making it a "do not miss" diagnosis.