A 45-year-old AIDS patient develops a focal brain lesion. Biopsy shows reactive astrocytes and large cells with multiple enlarged nuclei containing intranuclear inclusions. The pathogen is best identified by which staining?
- A PAS stain revealing capsulated yeast cells
- B India ink preparation identifying Cryptococcus neoformans
- C Immunohistochemistry for CMV antigen showing 'owl-eye' nuclear inclusions ✓
- D AFB staining for Mycobacterium tuberculosis
Correct answer: C. Immunohistochemistry for CMV antigen showing 'owl-eye' nuclear inclusions
Explanation
CMV encephalitis in immunocompromised (AIDS) patients shows characteristic 'owl-eye' nuclear inclusions — large amphophilic intranuclear inclusions surrounded by a clear halo — along with smaller cytoplasmic inclusions in infected cells (neurons, astrocytes, endothelial cells). IHC for CMV antigens confirms diagnosis. Cryptococcus causes meningitis with mucinous capsule (India ink positive); PAS detects fungal walls; AFB identifies mycobacteria. The multinucleated giant cell appearance with intranuclear inclusions is classic for CMV.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.