Hairy Leukoplakia in AIDS

Introduction

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A well-demarcated, painless, verruciform hyperkeratotic lesion of the lateral tongue in HIV-infected male homosexuals was first reported in 1981 as hairy leukoplakia. It appears to represent an Epstein-Barr virus-induced proliferation in an area of chronic trauma and is found in approximately 80% of AIDS patients. It is eventually also found in one of every 4 HIV-infected individuals. Its presence usually heralds progression into AIDS and is positively correlated with the depletion of peripheral CD4 cells. Occasional patients with other immunosuppression diseases, or without evidence of immunosuppression, will present with hairy leukoplakia.

Clinical Features

Hairy leukoplakia varies in its clinical appearance from a flat, white plaque to one with small or long white projections with pointed or blunted ends (Figures 1 & 2). Almost all AIDS-related cases have been on the lateral lingual margin, but occasional cases creep onto the ventral or dorsal surfaces or are found at another oral site, especially the buccal commissure. Many lateral tongue examples have vertical red or pink grooves evenly dispersed along the length of the lesion (Figure 3).

The lesion is asymptomatic, although a secondary infection by Candida albicans my produce tenderness or a burning sensation. It is important to remember that, despite its name, this is not a true leukoplakia and does not exhibit precancerous behavior.

Pathology and Differential Diagnosis

A hyperkeratotic surface is seen, usually with verruciform projections, sometimes with keratin-filled clefts between them (Figure 39a). Immediately beneath the parakeratosis is the characteristic feature of this lesion: a koilocytic appearance of large keratinocytes with intracellular "edema" and basophilic nuclear viral inclusions with peripheral displacement of chromatin (Figure 39b). The latter changes often impart a smudged appearance to the nucleus. Ballooning degeneration and perinuclear clearing may also be seen in occasional deeper cells and silver stains will often reveal candida hyphae within the superficial layers of the epithelium. There is usually only a mild chronic inflammatory cell response within underlying connective tissues. Immunohistochemistry or electron microscopy will demonstrate intranuclear Epstein-Barr virions.

This lesion must be differentiated from the previously mentioned verruciform lesions (see discussion in the pathology section relating to the papilloma), and must likewise be differentiated from verrucous carcinoma and hairy tongue. The carcinoma lacks the abrupt onset, early age at diagnosis, and keratinocytes with viral inclusions. It also demonstrates a blunt, pushing invasion of the underlying stroma, which is not seen in hairy leukoplakia. Hairy tongue is poorly demarcated clinically and produces a generalized keratotic change of the entire dorsum of the tongue. It may show occasional koilocytes but lacks the large virally-affected keratinocytes of hairy leukoplakia. Occasional cases of hyperplastic lichen planus will show verruciform surface changes, but the ballooning degeneration of that disease is confined to the basal layer and there are no viral inclusions in affected cells. Lichen planus also demonstrates a subepithelial band of chronic inflammatory cells, a feature not found in hairy leukoplakia.

Treatment and Prognosis

Hairy leukoplakia is a self-limiting lesion with no known potential for malignant transformation. Larger lesions may require conservative surgical removal because of constant trauma with adjacent teeth and interference with chewing, but most lesions can be left alone. The lesion may disappear spontaneously or with antiviral medications or with systemic AIDS therapies, but it often recurs. An incisional biopsy is almost always performed to confirm the diagnosis because of the close association with HIV infection and the high probability of an infected individual with hairy leukoplakia progressing to AIDS within 1-2 years of the leukoplakia diagnosis.

References (Chronologic Order)

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General references:

Neville BW, Damm DD, Allen CM, Bouquot JE. Oral and maxillofacial pathology. Philadelphia, W. B. Saunders; 1995.

Elder D, Elenitsas R, Jaworsky C, Johnson B Jr. Lever's Histopathology of the skin, 8th edition. Philadelphia; Lippincott-Raven, 1997.

Sapp JP, Eversole LR, Wysocki GP. Contemporary oral and maxillofacial pathology. Mosby; St. Louis, 1997.

Odell EW, Morgan PR. Biopsy pathology of the oral tissues. London; Chapman & hall Medical, 1998.

Specific references:

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