Infectious Disease · Opportunistic Infections
The facts most likely to be tested
CMV retinitis in AIDS patients typically presents with blurred vision, floaters, and scotoma when the CD4 count drops below 50 cells/µL.
Funduscopic examination of CMV retinitis reveals classic yellow-white perivascular hemorrhages and fluffy exudates described as pizza pie retinopathy.
CMV esophagitis is characterized by large, shallow, linear esophageal ulcers seen on endoscopy in immunocompromised hosts.
CMV colitis presents with bloody diarrhea, abdominal pain, and weight loss in patients with advanced HIV/AIDS.
Congenital CMV infection is the most common congenital viral infection and typically presents with sensorineural hearing loss, periventricular calcifications, and petechiae (blueberry muffin rash).
The first-line treatment for sight-threatening CMV retinitis is intravitreal ganciclovir or foscarnet injections.
Histopathologic examination of CMV-infected tissue reveals pathognomonic owl's eye inclusion bodies within enlarged cells.
Vignette unlocked
A 34-year-old male with a history of untreated HIV presents to the clinic complaining of progressive vision loss in his right eye over the past two weeks. He describes seeing 'floaters' and a dark spot in his peripheral vision. His most recent CD4 count was 32 cells/µL. On funduscopic examination, the physician notes yellow-white perivascular hemorrhages and fluffy exudates consistent with pizza pie retinopathy.
What is the most appropriate initial management for this patient?
Intravitreal ganciclovir or foscarnet
The patient presents with classic findings of CMV retinitis, which is an AIDS-defining illness occurring when CD4 counts are <50 cells/µL; sight-threatening lesions require local intravitreal therapy to prevent permanent blindness.
Full handout
High yield triage
Etiology / Epidemiology
Human herpesvirus-5; primary risk in immunocompromised (HIV CD4 <50, transplant recipients).
Clinical Manifestations
Retinitis presents as pizza pie fundus; colitis causes bloody diarrhea.
Diagnosis
PCR is the gold standard; biopsy shows owl's eye inclusions.
Treatment
Ganciclovir is first-line; neutropenia is a major dose-limiting side effect.
Prognosis
High mortality in untreated AIDS patients; requires lifelong HAART for immune recovery.
Full handout
Epidemiology & Etiology
CMV is a ubiquitous beta-herpesvirus that establishes latent infection in myeloid progenitor cells. Transmission occurs via bodily fluids, organ transplantation, or vertical transmission. Clinical disease is almost exclusively seen in the severely immunocompromised.
Pertinent Anatomy
CMV exhibits broad tissue tropism, most notably affecting the retina, gastrointestinal tract, and lungs. In the eye, it causes full-thickness necrotizing retinitis that can lead to rapid retinal detachment.
Pathophysiology
Primary infection is usually asymptomatic in immunocompetent hosts. Reactivation occurs when cell-mediated immunity fails, leading to systemic viremia and end-organ damage. The virus induces characteristic cytopathic changes in infected cells.
Clinical Manifestations
CMV retinitis presents with blurred vision and scotomas; fundoscopy reveals pizza pie appearance (hemorrhage and exudates). CMV colitis manifests as abdominal pain and bloody diarrhea. Retinal detachment is a surgical emergency requiring immediate ophthalmology referral.
Diagnosis
The gold standard for tissue diagnosis is biopsy showing owl's eye inclusions (intranuclear/intracytoplasmic). PCR is the preferred diagnostic test for viremia. In retinitis, the diagnosis is primarily clinical based on characteristic fundoscopic findings.
Treatment
Ganciclovir or Valganciclovir are the first-line agents for active disease. Neutropenia and thrombocytopenia are common adverse effects requiring frequent CBC monitoring. Foscarnet is reserved for ganciclovir-resistant strains or patients with severe bone marrow suppression.
Prognosis
Without immune reconstitution via HAART, recurrence is nearly universal. Retinal detachment remains the leading cause of permanent vision loss in AIDS-related CMV retinitis.
Differential Diagnosis
Toxoplasmosis: ring-enhancing lesions on MRI, not retinal necrosis
HSV Retinitis: associated with acute retinal necrosis and pain
Cryptosporidiosis: watery diarrhea, not bloody
EBV: mononucleosis-like syndrome, heterophile antibody positive
HIV Retinopathy: cotton-wool spots, no hemorrhage