Which condition presents with increased mononuclear leukocytes and enlarged neck lymph nodes?

• A. Celiac disease
• B. Mononucleosis
• C. Systemic lupus erythematosus
• D. Chronic fatigue syndrome

Answer: (B)

Infectious mononucleosis is characterized by a reactive increase in lymphocytes (mononuclear leukocytes) and prominent cervical (neck) lymphadenopathy. Epstein-Barr virus drives a lymphocyte-rich response, so counts show more mononuclear cells and the neck lymph nodes swell as part of the immune reaction. This pattern is classic for mononucleosis, often with fever, sore throat, and fatigue, and can be supported by a positive heterophile antibody test.

Celiac disease doesn’t typically present with a CBC showing increased mononuclear cells or with focal neck lymph node swelling; it’s mainly a gluten-triggered intestinal malabsorption syndrome. Systemic lupus erythematosus can cause lymph node enlargement but doesn’t standardly produce the mononuclear leukocytosis pattern. Chronic fatigue syndrome features long-standing fatigue without the characteristic CBC finding or neck lymphadenopathy.