Oral Lesions Induced by Chronic Khat Use Consist Essentially of Thickened Hyperkeratinized Epithelium

Abstract

Objectives. The habit of khat chewing is prevalent in many Middle Eastern and African cultures and has been associated with various adverse conditions in humans. This study aimed to describe histological changes induced by chronic khat chewing on the buccal mucosa. Methods. Biopsies of the buccal mucosa from 14 chronic khat chewers, 20 chronic khat chewers who also smoked tobacco, and 8 nonchewers were compared for epithelial thickness, degree and type of keratinization, and connective tissue changes. Results. Tissues from khat chewers depicted abnormal keratinization of the superficial cell layer and showed increased epithelial thickness affecting all layers. Epithelial thickness in control samples was 205 ± 26 μm whereas thickness in khat chewers and khat chewers who smoked tobacco was significantly higher measuring 330 ± 35 μm and 335 ± 19 μm, respectively. Tissues from khat chewers also showed increased intracellular edema, increased melanin pigment deposits, and increased number of rete pegs most of which were thin and deep. Conclusions. These results show that oral lesions induced by chronic chewing of khat in the buccal mucosa present with white and brown discoloration due to increased epithelial thickness, increased keratinization, and melanin deposition.

Khat (Catha edulis) and its oral health effects: An updated review

“…Mucosal pigmentation related to khat chewing has also been reported in the literature . Yarom et al .…”

“…attributed mucosal discoloration to the chemical components of khat. A recent study observed a high concentration of melanin in basal keratinocytes of tissue samples of chronic khat chewers, which could explain the mucosal discoloration at the khat chewing site …”

“…The reported histopathological changes in the oral mucosa on the side of chewing were acanthosis, abnormal rete ridges, intracellular edema, hyperkeratosis, increased epithelial thickness affecting all layers, and inflammatory cell infiltration in the subjacent connective tissue . Because these changes were benign and had no evidence of malignancy, some authors have stated that these lesions were secondary to frictional and/or chemical pathogenesis, not amounting to premalignancy …”

“…Other reported mucosal changes associated with khat chewing include mucosal pigmentation, ulcers, stomatitis, plasma cell mucositis, reactive benign swelling, and hairy tongue . Luqman and Danowski reported that long‐term khat chewing caused stomatitis, followed by secondary infection, which could be related to mechanical strain on the cheek and other oral tissues, as well as chemical irritation of the mucosal surfaces…”

“…Khat use has also been reported to have detrimental effects on dental and oral tissues. These include periodontal diseases, dental discoloration and attrition, temporomandibular joint disorders, plasma cell stomatitis, mucosal pigmentation, keratotic lesions, and xerostomia . Furthermore, some investigators have suggested a possible link between khat chewing and oral cancer .…”