A 19-year-old college student presents with fever, pharyngitis, cervical lymphadenopathy, and fatigue for 10 days. Peripheral blood smear shows atypical lymphocytes. Which laboratory test is most appropriate for confirming the suspected diagnosis?
- A Heterophile antibody test (Monospot) ✓
- B Anti-EBV viral capsid antigen IgM
- C EBV DNA PCR
- D Anti-EBV nuclear antigen IgG
Correct answer: A. Heterophile antibody test (Monospot)
Explanation
The clinical presentation is classic for infectious mononucleosis caused by EBV. The heterophile antibody test (Monospot) is the initial screening test of choice, detecting IgM antibodies that agglutinate sheep or horse red blood cells. It is positive in about 85% of cases in the second week. Anti-VCA IgM is more sensitive but used when Monospot is negative. EBNA IgG appears late and indicates past infection.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.