What is the cause of leukocytosis (elevated White Blood Cell count) with neutrophilia (elevated neutrophil count) in a 54-year-old morbidly obese male (Body Mass Index over 80) with no recent infections?

Differential Diagnosis for a 54-year-old Male with Elevated WBC

Single Most Likely Diagnosis

• Chronic Leukocytosis associated with Obesity: The patient's morbid obesity (BMI over 80) is a significant factor. Chronic inflammation and metabolic changes associated with obesity can lead to a persistent, mild to moderate increase in white blood cell count, particularly neutrophils.

Other Likely Diagnoses

• Chronic Myeloid Leukemia (CML): Although less likely without other symptoms, CML can present with a elevated WBC count, predominantly neutrophils, and the patient's age is within the typical range for diagnosis.
• Polycythemia Vera: A myeloproliferative disorder that can cause an increase in all blood cell lines, including WBC. The patient's obesity and potential for associated metabolic syndrome increase the likelihood.
• Reactive Leukocytosis due to Chronic Inflammation: Conditions like chronic gastritis, diverticulitis, or other low-grade infections/inflammatory processes could cause a persistent elevation in WBC, though the patient reports no recent infections.

Do Not Miss Diagnoses

• Acute Leukemia: Although the patient is asymptomatic, acute leukemia (e.g., Acute Myeloid Leukemia) can present with elevated WBC counts and must be ruled out due to its aggressive nature and need for immediate treatment.
• Infectious Diseases (e.g., Tuberculosis, Endocarditis): Chronic infections can cause a persistent leukocytosis. These conditions are critical to diagnose early due to their potential for severe morbidity and mortality.
• Lymphoma: Certain types of lymphoma can present with elevated WBC counts, and given the potential for lymphoma in this age group, it should be considered.

Rare Diagnoses

• Myeloproliferative Neoplasms (other than CML or Polycythemia Vera): Conditions like Essential Thrombocythemia or Primary Myelofibrosis are less common but could explain the elevated WBC count.
• Leukocyte Adhesion Deficiency: A rare immunodeficiency disorder that can cause persistent leukocytosis due to the inability of leukocytes to migrate to sites of infection.
• Familial Leukocytosis: A rare, benign condition characterized by a persistent increase in WBC count without an underlying inflammatory or malignant cause.