Differential Diagnosis for High WBC, Lymphocytes, Eosinophils but Afebrile

• Single Most Likely Diagnosis
  • Allergic reaction or atopy: This is often characterized by an increase in eosinophils and can also cause a rise in lymphocytes. The absence of fever suggests a non-infectious cause, making allergic reactions a plausible explanation.
• Other Likely Diagnoses
  • Parasitic infection: Certain parasitic infections can cause eosinophilia and lymphocytosis without fever, especially in the early stages or in chronic infections.
  • Asthma or chronic obstructive pulmonary disease (COPD) exacerbation: Both conditions can lead to increased eosinophils and may also affect lymphocyte counts. The absence of fever does not rule out these conditions.
  • Drug reaction: Some medications can induce eosinophilia and lymphocytosis as part of a drug reaction, which may not necessarily be accompanied by fever.
• Do Not Miss Diagnoses
  • Lymphoproliferative disorders (e.g., lymphoma): Although less common, these conditions can present with lymphocytosis and sometimes eosinophilia. Missing such a diagnosis could have severe consequences.
  • Hypereosinophilic syndrome (HES): A rare condition characterized by persistent eosinophilia that can lead to organ damage. It is crucial to consider this diagnosis to prevent long-term complications.
  • Churg-Strauss syndrome (eosinophilic granulomatosis with polyangiitis): A form of vasculitis that can present with eosinophilia, lymphocytosis, and is often associated with asthma or allergic rhinitis. It's a potentially life-threatening condition if not treated.
• Rare Diagnoses
  • Idiopathic hypereosinophilic syndrome: A condition of unknown cause characterized by elevated eosinophils, which can sometimes be associated with lymphocytosis.
  • Eosinophilic leukemia: A rare form of leukemia that can present with eosinophilia and may also affect lymphocyte counts.
  • Other rare parasitic infections or exotic diseases that might cause similar laboratory findings, depending on the patient's travel history or exposure.