Differential Diagnosis for Chronic Elevation of WBC and Lymphocytes

Single Most Likely Diagnosis

• Chronic Stress or Smoking-Induced Leukocytosis: The patient's smoking history and elevated heart rate (HR 111) could indicate chronic stress, which can lead to a sustained increase in white blood cell (WBC) count, including lymphocytes. Smoking is a well-known cause of chronic leukocytosis.

Other Likely Diagnoses

• Serotonin-Related Medication Side Effect: Given the patient's polypharmacy with many serotonin-affecting medications, it's plausible that the chronic elevation of WBC and lymphocytes could be a side effect of these medications. Some drugs can cause changes in blood cell counts.
• Chronic Infection or Inflammation: Although the patient has no complaints, a low-grade, chronic infection or inflammatory process could be causing the elevated WBC and lymphocyte count. This could be related to the patient's smoking history or other underlying conditions.
• Lymphoproliferative Disorder: Conditions like chronic lymphocytic leukemia (CLL) or lymphocytosis with monoclonal B-cell lymphocytosis could present with a chronic elevation of lymphocytes. However, these conditions often have other associated symptoms or findings.

Do Not Miss Diagnoses

• Leukemia (e.g., Chronic Lymphocytic Leukemia, CLL): While potentially less likely without other symptoms, leukemia must be considered due to its significant implications. CLL can present with lymphocytosis and may be asymptomatic for a long time.
• Lymphoma: Similar to leukemia, lymphoma is a critical diagnosis not to miss. It can cause chronic elevation of lymphocytes and may not always present with overt symptoms early in the disease.
• Chronic Myeloid Leukemia (CML): CML can cause an elevation in WBC count, including lymphocytes, and is a diagnosis that significantly impacts treatment and prognosis.

Rare Diagnoses

• Primary Immunodeficiency Disorders: Certain immunodeficiency disorders can present with abnormal lymphocyte counts. These are rare and usually have other clinical manifestations.
• Castleman Disease: A rare disorder that can cause an increase in lymphocytes among other symptoms. It's often associated with lymphadenopathy and systemic symptoms, which are not mentioned in the scenario.
• Familial Lymphohistiocytosis: A rare genetic disorder that affects the immune system and can cause elevated lymphocytes, though it typically presents with more severe systemic symptoms.