Effect of irinotecan on the tongue mucosa of juvenile male albino rat at adulthood.

Irinotecan is one of the most important anti-tumour drugs against a broad spectrum of malignancies, but is known to be associated with possible oral complications. The aim of the present study was to evaluate the effect of irinotecan on the tongue mucosa of juvenile male albino rat at adulthood using different histological and immunohistochemical methods. Twenty juvenile male albino rats were divided equally into two groups: control and irinotecan-treated group (single injection of 200 mg irinotecan/kg, then kept for four weeks without treatment). The tongue specimens were processed for light microscopy and scanning electron microscopy. The irinotecan-treated group showed statistically significant shortening and thinning of the lingual papillae. There was loss of the normal appearance of the filiform papillae with focal cell loss alternating with areas of hyperkeratosis. Focal separation of the keratin layer, some nuclear changes and vacuolation of some epithelial cells were detected. Dilated congested blood vessels and mild mononuclear cellular infiltration were encountered. Atrophic fungiform papillae with ill-defined taste bud cells were observed. A statistically significant decrease in the pattern of Ki67 immunohistochemical staining reaction was detected in comparision to the control group. Scanning electron microscopy revealed different signs of atrophy of the tongue papillae. Focal areas of desquamation of lingual papillae were observed revealing some filiform papillae with desquamated surface, bisected tips and evident thinning. Some extravasated red blood cells could be detected. Thus irinotecan caused significant morphological and morphometrical alterations of the tongue mucosa in particularly the filiform papillae.