Differential Diagnosis

The patient's laboratory results show a WBC count of 4.8, with a high neutrophil percentage, low lymphocyte percentage, and high monocyte percentage. Based on these findings, the following differential diagnoses are considered:

• Single most likely diagnosis
  • Acute Bacterial Infection: The high neutrophil percentage is indicative of a bacterial infection, which is a common cause of elevated neutrophils. The low lymphocyte percentage and high monocyte percentage also support this diagnosis, as monocytes are often elevated in response to infection.
• Other Likely diagnoses
  • Chronic Inflammation: Conditions such as rheumatoid arthritis, lupus, or other autoimmune disorders can cause a high neutrophil percentage and low lymphocyte percentage. The high monocyte percentage also supports this diagnosis, as monocytes are often elevated in chronic inflammatory conditions.
  • Smoking or Exposure to Toxins: Smoking and exposure to certain toxins can cause an increase in neutrophils and monocytes, while decreasing lymphocytes.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Sepsis: Although the WBC count is not significantly elevated, sepsis can present with a normal or low WBC count, especially in elderly or immunocompromised patients. The high neutrophil percentage and low lymphocyte percentage could be indicative of sepsis, and it is crucial to consider this diagnosis due to its high mortality rate.
  • Hematologic Malignancy: Certain types of leukemia or lymphoma can cause abnormal WBC counts and differentials. Although less likely, it is essential to consider these diagnoses due to their potential severity and impact on treatment.
• Rare diagnoses
  • Myeloproliferative Neoplasm: Conditions such as polycythemia vera or essential thrombocytosis can cause an increase in neutrophils and monocytes. However, these diagnoses are less common and would require further testing to confirm.
  • Myelodysplastic Syndrome: This group of disorders can cause abnormal WBC counts and differentials, including a high neutrophil percentage and low lymphocyte percentage. However, these diagnoses are rare and would require bone marrow biopsy and other tests to confirm.