- OHL is caused by infection with Epstein-Barr virus (EBV), and usually presents as corrugated white plaques of the lateral tongue.
- OHL is a clinical manifestation of immunosuppression and classically presents in the setting of HIV infection.
- OHL is a chronic condition that is managed over time rather than cured. Therapy is only indicated if it is symptomatic.
Oral hairy leukoplakia (OHL) has to date been pathognomonic of immunosuppression usually due to HIV infection. In one series, it was present in 11.5% of HIV-infected individuals, designating it as the fourth most common oral manifestation in this population after oral candidiasis (39.3%), melanotic hyperpigmentation (19.5%), and oral ulcers (11.8%). Other studies investigating oral manifestations in this population have determined a lower prevalence in the range of 0.33-2.7%. OHL is caused by reactivation of Epstein-Barr virus (EBV), a virus that infects up to 90% of all adults, though commonly asymptomatic in immunocompetent hosts. It is classically an opportunistic infection of HIV-infected individuals; risk of reactivation increases with elevated viral load and reduced CD4 lymphocyte count. OHL has also been described in other immunocompromised individuals, including patients with hematologic malignancy, persons undergoing chemotherapy, and organ transplant recipients. Increased numbers of EBV-infected B cells and reduced numbers of EBV-specific cytotoxic T cells noted in biopsies of OHL, in addition to the absence or reduced number of Langerhans cells, suggest key immunologic factors associated with viral reactivation in affected lesions.
Clinically, OHL typically presents as vertically corrugated white lesions of the lateral tongue. It may be unilateral or bilateral, and may also affect the dorsal or ventral tongue, gingiva, or oral mucosa. Lesions of OHL may appear as smooth white papules or plaques with a broad range of morphologic variation, including corrugation or papillated surfaces. A key feature distinguishing OHL from common oral mucosal diseases such as candidiasis is that OHL is firmly adherent to the mucosal or tongue surface, whereas lesions stemming from candida are relatively easily removed by a scalpel blade. A second distinguishing feature of OHL is that there is typically an absence of erythema or inflammation underlying the white papules or plaques. It is characteristically asymptomatic, though patients may complain of dysgeusia, dysesthesia, mild pain, or concerns regarding cosmetic appearance. Biopsy reveals characteristic histopathologic features including epithelial hyperkeratosis with papillomatosis, acanthosis, and ballooning degeneration within the epidermis. Viral changes can also be noted and also detected by immunohistochemistry or by in situ hybridization. Since the EBV infection is chronic and lifelong, therapy will clear but will not cure lesions, and OHL will usually reappear once treatment is stopped. Therapy is usually not indicated, as OHL is asymptomatic and may remit spontaneously in 10% of cases. OHL will also resolve in association with immune reconstitution due to anti-retroviral medications. Pseudo-OHL is clinically similar but does not contain EBV, allowing differentiation by histological examination.