AANP Family Nurse Practitioner (FNP) Certification ExamDiagnosisMedium
A 22-year-old female presents with a 3-week history of fatigue, generalized weakness, and a sore throat. On examination, she has bilateral posterior cervical lymphadenopathy, pharyngeal erythema with exudates, and mild splenomegaly. Rapid strep test is negative. Her CBC shows lymphocytosis with atypical lymphocytes. What is the most likely diagnosis?
- ACytomegalovirus (CMV) Infection
- BInfectious Mononucleosis
- CBacterial Pharyngitis
- DAcute Lymphoblastic Leukemia
Show answer & explanationAnswer & explanation
Correct answer: B. Infectious Mononucleosis
The classic triad of fever (implied by fatigue/sore throat for 3 weeks), pharyngitis, and lymphadenopathy (especially posterior cervical), combined with fatigue, splenomegaly, and atypical lymphocytes on CBC, strongly points to Infectious Mononucleosis, typically caused by Epstein-Barr Virus (EBV).
Why the other options are wrong
- A. CMV infection can cause a mononucleosis-like syndrome, but EBV is far more common in this age group and presents with these specific findings.
- C. Bacterial pharyngitis (strep throat) is usually acute, responds to antibiotics, and typically presents with anterior cervical lymphadenopathy, and a negative rapid strep test makes it less likely.
- D. Acute Lymphoblastic Leukemia is a severe malignancy, usually presenting with more profound constitutional symptoms, cytopenias, and blast cells in the peripheral blood, not just atypical lymphocytes.
Infectious Mononucleosis
A common infectious disease, usually caused by the Epstein-Barr virus, characterized by fever, sore throat, fatigue, and swollen lymph nodes.
- Transmitted via saliva (kissing disease).
- Hallmark features include fatigue, pharyngitis, lymphadenopathy, and splenomegaly.
- Diagnosis confirmed by Monospot test or EBV serology and atypical lymphocytes on CBC.
Memory trick: MONO: Monospot positive, Oral exudates, Node swollen, Other symptoms (splenomegaly, fatigue).