TOOMBAK-ASSOCIATED ORAL MUCOSAL LESIONS IN SUDANESE SHOW A LOW-PREVALENCE OF EPITHELIAL DYSPLASIA

Clinical (n=281) and histopathological (n=141) characteristics of toom bak-associated oral mucosal lesions detected in an epidemiological stu dy in northern Sudan in 1992/93 are described. The lesional site in th e majority of toombak users was the anterior lower labial groove and t he lower labial mucosa. 4 degrees (1-4) of clinical severity of lesion s, similar to those used to characterise Swedish snuff-dipper's lesion , were applied. An association between the severity of mucosal lesions and a longer lifetime duration (>10 years) of toombak use was found, but the severity was not related to the daily frequency of the habit. Parakeratosis, pale surface staining of the epithelium and basal cell hyperplasia were commonly observed, but epithelial dysplasia was infre quent (10/141). The most significant observation was a PAS-positive am orphous deposit between the lamina propria and the submucosa, found in 25/141 biopsies. The clinical and histopathological features of toomb ak lesions are closely similar to Swedish moist snuff-dipper's lesions and this may reflect the high alkalinity of these products, resulting in an alkaline burn on the oral mucosa following chronic exposure. Th e low prevalence of epithelial dysplasia implies a low risk of maligna nt transformation. Nevertheless, the high concentrations of tobacco-sp ecific nitrosamines present in toombak, and the high prevalence of ora l cancer in Sudan, mandate biopsy and careful histopathological analys is of any such lesions detected in habitues.