A Comparative Histochemical Study of Mucous Cells in Odontogenic Cysts

The diagnosis of a glandular odontogenic cyst (GOC) on an incisional biopsy continues to remain a diagnostic challenge for the histopathologist. A marker for distinguishing GOC from odontogenic cysts with mucous metaplasia is thus needed in routine pathology practice. This study aimed to determine the histochemical composition of the mucous cells in the GOC and to compare the findings with the mucous cells in odontogenic cysts that show overlapping histomorphological features with the GOC. GOCs ( ), dentigerous cysts (DCs) ( ), and radicular cysts (RCs) ( ) with mucous metaplasia were stained using the combined alcian blue(pH 2.5)-PAS histochemical technique. The cysts were evaluated for the frequencies of acidic- (type I), neutral- (type II) and mixed- (acidic and neutral (type III)) mucin containing cells. Significant differences were found between the levels of type I, type II, and type III mucous cells within the 3 cyst types, GOC ( ), DC ( ), and RC ( ), which all showed a predominance of type III mucous cells. There were, however, no significant differences for each mucous cell type between the 3 cyst types. GOC thus appears to share the same histochemical mucin phenotype with the mucous cells in DC and RC. 1. Introduction The occurrence of mucous cells in odontogenic lesions is a rare but well-recognised phenomenon [1–5]. Those odontogenic cysts that have a tendency for showing mucous cells in their cyst linings include dentigerous cysts (DC), radicular cysts and residual radicular cysts (RC), and, by definition, glandular odontogenic cysts (GOC) [1–4, 6]. The pathological basis for the transition from the usually nonmucinous odontogenic epithelium to cells that produce mucin is poorly understood. On the basis of the presence of clear or vacuolated cells that are occasionally observed near the mucous cells in the epithelial linings of these cysts, it has been suggested that the mucous cells arise as a consequence of a metaplastic process in these cysts [4]. Other theories include grafting of mucous cells from a contiguous epithelium such as the maxillary sinus or from embryological pluripotential cells in the epithelial residues from which these cysts arise [1, 2]. Although the histogenesis of GOCs remains uncertain, it is widely believed that these cysts originate from odontogenic epithelium [7]. This is borne out to a considerable extent by many histomorphological characteristics of the GOC that are reminiscent of odontogenic lesions [8]. The presence of duct—like structures and mucous—producing cells is, however, not unique to the GOC as these