VIRUS · Enveloped dsDNA herpesvirus (β-herpesvirus)
Cytomegalovirus (HHV-5)
Cytomegalovirus — Owl's-eye intranuclear inclusion
Stain: H&E (histopathology)Morphology: Markedly enlarged 'cytomegalic' cell with large basophilic intranuclear inclusion surrounded by clear halo ('owl's-eye') plus smaller cytoplasmic inclusionsYield: HIGHDifficulty: MEDIUM
Image: Wikimedia Commons · Jensflorian (CC BY-SA 4.0)
Key facts
**Pathogenesis**: Establishes latency in monocytes and CD34+ progenitors; reactivates in immunocompromised hosts. Congenital infection is the #1 viral cause of birth defects (SNHL, periventricular calcifications, microcephaly). **Diagnostic clue**: Owl's-eye intranuclear inclusions on biopsy; CMV PCR / pp65 antigenemia; congenital CMV → 'blueberry muffin' rash, hearing loss, periventricular calcifications; AIDS retinitis with hemorrhages ('pizza pie' fundus). **Virulence**: Immune evasion via MHC-I downregulation, latency.
Boards buzzwords
- owl's-eye inclusion
- cytomegalic cell
- heterophile-negative mononucleosis
- TORCH
- retinitis with hemorrhages
- transplant infection
Associated diseases
- Congenital CMV (TORCH)
- Heterophile-negative mononucleosis
- CMV retinitis (AIDS CD4 <50)
- CMV pneumonitis / colitis / esophagitis in transplant
- CMV encephalitis
Treatment
Ganciclovir (or valganciclovir PO); foscarnet or cidofovir for resistant strains; letermovir prophylaxis in SCT; treat congenital CMV with (val)ganciclovir to preserve hearing
