Differential Diagnosis for Mildly Low WBC in a Healthy 36-year-old Female

Single Most Likely Diagnosis

• Benign Ethnic Neutropenia: This condition is characterized by a mildly low white blood cell (WBC) count, particularly neutrophils, in otherwise healthy individuals, often seen in people of African or Middle Eastern descent. The patient's WBC count fluctuations and the absence of other symptoms make this a plausible explanation.

Other Likely Diagnoses

• Viral Infections: Certain viral infections can cause a temporary decrease in WBC count. Given the patient's otherwise healthy status, a recent or ongoing viral infection could be a reason for the mildly low WBC count.
• Physiological Variations: WBC counts can vary due to physiological states such as stress, sleep, or time of day. These variations might account for the fluctuations in the patient's WBC count.
• Laboratory Error: Although less common, errors in laboratory testing or sample handling could lead to inaccurately low WBC counts.

Do Not Miss Diagnoses

• HIV Infection: Early stages of HIV infection can present with a low WBC count. It is crucial to consider and rule out HIV due to its significant implications for patient management and prognosis.
• Leukemia or Lymphoma: Although less likely, certain types of leukemia or lymphoma can initially present with a mildly decreased WBC count. These conditions are critical to identify early due to their potential for severe outcomes if left untreated.
• Autoimmune Disorders: Conditions like systemic lupus erythematosus (SLE) can cause leukopenia. Identifying such disorders is vital due to their potential for significant morbidity.

Rare Diagnoses

• Congenital Neutropenias: These are rare conditions present from birth that affect the production of neutrophils, leading to recurrent infections. They are less likely in a previously healthy adult but should be considered in the differential diagnosis.
• Cyclic Neutropenia: A rare condition characterized by periodic fluctuations in neutrophil count, which could potentially explain the variability in the patient's WBC counts.
• Drug-Induced Neutropenia: Certain medications can cause a decrease in WBC count. If the patient is on any medications, this possibility should be explored, although it might be less likely given the description of the patient as "healthy."