## **Core Concept**
The patient's presentation with fatigue, recurrent fever, enlarged cervical lymph nodes, and numerous atypical lymphocytes in the peripheral blood smear suggests a lymphoproliferative disorder. The biopsy findings of expanded lymphoid follicles with preserved underlying architecture and atypical lymphocytes in the paracortical areas are characteristic of a specific type of lymphoma.

## **Why the Correct Answer is Right**
The clinical presentation and biopsy findings are consistent with **Infectious Mononucleosis (IMN)**, also known as glandular fever, which is caused by **Epstein-Barr Virus (EBV)**. The hallmark histopathological features include:
- Preservation of the lymph node architecture
- Expansion of lymphoid follicles
- Atypical lymphocytes, particularly in the paracortical areas

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because, although it might represent a type of lymphoma, the specific details provided do not match the classic presentation of the disease it represents.
- **Option B:** This option is incorrect as it does not align with the clinical and histopathological findings described.
- **Option C:** This option is incorrect because it represents a different pathological entity that does not match the provided clinical scenario.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that **Infectious Mononucleosis** often presents with **atypical lymphocytosis** and can mimic lymphoma on initial evaluation. The presence of **heterophile antibodies** (Monospot test) and **EBV serology** can help confirm the diagnosis.

## **Correct Answer:** D. Infectious Mononucleosis.