**Question:** Pathologic features of brain in AIDS are all, except -

A. Encephalitis
B. Meningitis
C. Subacute sclerosing panencephalitis (SSPE)
D. Acute disseminated encephalomyelitis (ADE)

**Core Concept:** AIDS stands for Acquired Immunodeficiency Syndrome, caused by the Human Immunodeficiency Virus (HIV). In the late stages of HIV infection, neurological complications occur due to the destruction of immune cells, particularly CD4+ T-cells. AIDS can lead to various CNS (Central Nervous System) infections, demyelination, and opportunistic infections.

**Why the Correct Answer is Right:**

D. Acute disseminated encephalomyelitis (ADE) is a demyelinating disorder that typically occurs in the acute phase of an infection or vaccination. It is not a characteristic feature of AIDS, as it develops in the context of acute illness, rather than the chronic course of HIV infection.

**Why Each Wrong Option is Incorrect:**

A. Encephalitis is a common neurological complication of AIDS, as HIV can directly infect neurons, leading to inflammation and dysfunction.
B. Meningitis is another common AIDS complication, where the virus affects the meninges, leading to inflammation and potential neurological symptoms.
C. Subacute sclerosing panencephalitis (SSPE) is a late complication of previous Measles infection, not AIDS. It is a late-stage complication of Measles virus infection, occurring in immunocompromised individuals. AIDS is a separate condition caused by HIV, which affects the immune system differently.

**Clinical Pearl:**

Understanding the differential diagnosis between AIDS-related neurological complications and other infections is crucial for accurate diagnosis and appropriate treatment. AIDS-related neurological complications can present similarly to other conditions, so a comprehensive history, clinical examination, and appropriate investigations are essential for reaching a correct diagnosis.

**Correct Answer:** B. Meningitis