An 8 year old boy presented with fever and bilateral cervical lymphadenopathy with prior history of sore throat. There was no hepatomegaly. The peripheral blood smear shows > 20% lympho–plasmacytoid cells. The most likely diagnosis is –
An 8 year old boy presented with fever and bilateral cervical lymphadenopathy with prior history of sore throat. There was no hepatomegaly. The peripheral blood smear shows > 20% lympho–plasmacytoid cells. The most likely diagnosis is –
💡 Explanation
## **Core Concept**
The question presents a clinical scenario suggestive of an infectious or hematological disorder in a pediatric patient. The key findings include fever, bilateral cervical lymphadenopathy, a history of sore throat, and specific blood smear results. The presence of lympho-plasmacytoid cells on the peripheral blood smear is particularly noteworthy.
## **Why the Correct Answer is Right**
The description provided points towards **Infectious Mononucleosis (IMN)**, also known as glandular fever, which is commonly caused by Epstein-Barr Virus (EBV). The clinical presentation of fever, lymphadenopathy (particularly cervical), and a preceding sore throat are classic. The presence of >20% lympho-plasmacytoid cells or atypical lymphocytes on the blood smear is a hallmark of this condition. These cells are a type of reactive lymphocyte that appears in response to viral infections, among other causes.
## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is not provided, but we can infer that any diagnosis not aligning with the clinical and lab findings presented would be incorrect.
- **Option B:** Without the specific details of Option B, we can deduce that any condition not characterized by lympho-plasmacytoid cells, lymphadenopathy, and a viral prodrome would not fit.
- **Option C:** Similarly, Option C would be incorrect if it doesn't match the clinical picture of infectious mononucleosis or if it suggests a condition not typically associated with such a high percentage of lympho-plasmacytoid cells on the blood smear.
- **Option D:** This would be incorrect for similar reasons as Options B and C, primarily if it suggests an alternative diagnosis not supported by the clinical and laboratory findings.
## **Clinical Pearl / High-Yield Fact**
A key clinical pearl in this scenario is the importance of considering infectious mononucleosis in patients presenting with fever, lymphadenopathy, and atypical lymphocytosis, especially in the context of a recent sore throat. A classic, though not universally present, finding is the **heterophile antibody test** (Monospot test), which, while not definitive, can support the diagnosis. Remember, the Paul-Bunnell test is more specific but less commonly used.