What are the causes of oral hairy leukoplakia (OHL)?

From the Guidelines

Oral hairy leukoplakia (OHL) is primarily caused by the Epstein-Barr virus (EBV) infection in individuals with compromised immune systems, as supported by various studies, although not directly mentioned in the provided evidence 1. The condition occurs most commonly in people with HIV/AIDS, but can also affect those undergoing immunosuppressive therapy following organ transplantation, patients receiving long-term steroid treatment, or individuals with other conditions that weaken the immune system.

• Key factors that contribute to the development of OHL include:
  • Immunosuppression, which allows the EBV to reactivate from its latent state and replicate within the epithelial cells of the tongue
  • EBV infection, which is a necessary factor for the development of OHL
  • Weakened immune response, which enables the virus to actively replicate and cause epithelial cell proliferation The provided evidence 1 discusses various oral lesions that can occur in patients with chronic kidney disease (CKD), including lichenoid oral lesions and uremic stomatitis, but does not directly address the causes of OHL. However, it does mention that oral hairy leukoplakia can occur after immunosuppressive drug therapy, particularly when BUN levels are above 300 mg·mL−1, which suggests that immunosuppression is a key factor in the development of OHL.
• The clinical implications of OHL include:
  • Serving as an important clinical marker for underlying immunosuppression, particularly in undiagnosed HIV infection
  • Indicating disease progression in known HIV-positive individuals
  • Requiring prompt evaluation and management to prevent further complications and improve patient outcomes.

From the Research

Causes of Oral Hairy Leukoplakia (OHL)

• Oral hairy leukoplakia (OHL) is caused by the reactivation of a previous Epstein-Barr virus (EBV) infection in the epithelium of the tongue 2, 3, 4, 5.
• The condition is frequently associated with AIDS, but cases in patients with other immunosuppressed states have also been reported 2, 6.
• OHL can occur in patients with no evidence of immunosuppression, including healthy immunocompetent patients 4, 5.
• The use of immune-modulating medications, such as cyclosporine, may also be a contributing factor in the development of OHL in HIV-negative patients 4.
• A significant decrease in Langerhans cell counts has been observed in OHL patients, which may be related to the pathogenesis of the condition 4.

Association with Immunocompromised States

• OHL is a marker of moderate to advanced immunodeficiency and disease progression in patients with HIV infection 6.
• The condition is nearly exclusively seen in men infected with HIV, and is associated with significant immunosuppression 6.
• However, OHL should no longer be regarded as pathognomonic for HIV infection or systemic immunosuppression, as it can occur in immunocompetent individuals 5.

Clinical Characteristics

• OHL is characterized by corrugated whitish patches on the lateral border of the tongue, which cannot be scraped from the surface it adheres to 2, 5.
• The lesions are often asymptomatic and soft, and may be associated with hyperparakeratosis, candidiasis, acanthosis, and a band-like zone with clearing of cells in the upper spinous layer 4.