CHARACTERIZATION OF AN AMORPHOUS DEPOSIT IN THE LAMINA PROPRIA IN ORAL SNUFF USERS IN THE SUDAN AS COLLAGEN

Histological and ultrastructural features of 25 oral snuff dipper's le sions with distinctive subepithelial hyaline deposits were investigate d. Periodic acid-Schiff reaction with and without diastase digestion d emonstrated the presence of glycogen and other carbohydrates, but hist ochemical stains for normal collagen, elastin and fibrin showed a weak variable reactivity of the deposit. Although in 7/25 cases the deposi t was in close proximity to labial salivary glands and on occasions du cts were found within the deposit, the presence of mucin was not a con sistent feature. Congo red staining and immunohistochemical investigat ion with an anti-amyloid antibody did not support the previous content ion that such deposits were amyloid in nature. Immunohistochemically, collagen antibodies also provided negative results, but ultrastructura l features of three biopsies studied suggest that the bulk of this dep osit is made up of collagen, as typical cross-striated fibrils were fo und. The pathogenesis of this deposit could therefore be interpreted a s over-production and/or reduced turnover of collagen by resident fibr oblasts, which is further altered by the ingredients of toombak. The d eposit does not appear to be a secretory product.