Lymph node biopsy of an AIDS patient shows:March 2009
**Core Concept**
The question is testing the student's knowledge of opportunistic infections in immunocompromised patients, specifically those with AIDS. The underlying concept is the pathophysiology of various infections that take advantage of a weakened immune system.
**Why the Correct Answer is Right**
In AIDS patients, the lymph nodes can be affected by various opportunistic infections, including tuberculosis (TB), Kaposi's sarcoma, lymphoma, and cytomegalovirus (CMV) infection. However, the most common opportunistic infection affecting lymph nodes in AIDS patients is **Kaposi's sarcoma**. Kaposi's sarcoma is a type of cancer that forms in the lining of blood and lymph vessels, and it is caused by human herpesvirus 8 (HHV-8). It typically presents as purple lesions on the skin, but it can also affect internal organs, including the lymph nodes.
**Why Each Wrong Option is Incorrect**
* **Option A:** Tuberculosis (TB) is indeed an opportunistic infection that affects immunocompromised patients, but it is not the most common cause of lymphadenopathy in AIDS patients. TB typically presents with granulomatous inflammation and caseating necrosis.
* **Option B:** Lymphoma is a type of cancer that affects the immune system, but it is not the most common opportunistic infection affecting lymph nodes in AIDS patients. There are several types of lymphoma, including Hodgkin's lymphoma and non-Hodgkin's lymphoma.
* **Option D:** Cytomegalovirus (CMV) infection is a common opportunistic infection in AIDS patients, but it typically affects other organs, such as the retina and the gastrointestinal tract, rather than the lymph nodes.
**Clinical Pearl / High-Yield Fact**
In AIDS patients, Kaposi's sarcoma is often associated with a poor prognosis, and it is a marker of advanced immunosuppression. The presence of Kaposi's sarcoma in a lymph node biopsy should prompt a thorough evaluation of the patient's immune status and the consideration of antiretroviral therapy.
**Correct Answer:** C.