Peripheral odontogenic tumor: a clinicopathologic study of 30 cases. General features and hamartomatous lesions
F. Ide1,2,3, K. Obara2, K. Mishima2, I. Saito2, N. Horie3, T. Shimoyama3, K. Kusama1
Division of Pathology, Department of Diagnostic and Therapeutic Sciences,Meikai University School of Dentistry, Saitama; Department of Pathology, Tsurumi University School of Dental Medicine, Yokohama; 3Department of Oral Surgery, Saitama Medical Center, Saitama, Japan
BACKGROUND: Peripheral odontogenic tumors (POT), either neoplastic or hamartomatous, are rare. This study brieﬂy summarizes the general features of POT and selectively reviews the histomorphologicspectrum of under-recognized hamartomatous lesions that we have designated peripheral odontogenic hamartomas (POH) in order to shed more light into the pathogenesis of POT. METHODS: Archival material accessioned at our institutions between 1970 and 2004 was systematically searched to identify examples of POT/POH. RESULTS: Among 39 660 biopsies, we retrieved 25 cases of ‘classical’ POT and ﬁvecases of ‘unique’ POH. Odontogenic ﬁbroma and ameloblastoma were by far the most common. Of POH, two purely epithelial lesions showed multiple strands of basaloid rests [odontogenic gingival epithelial hamartoma (OGEH)] and a conglomerate of polyhedral epithelium, ghost cells and concentric calciﬁcations (calcifying epithelial odontogenic tumor-like hamartoma), respectively. OGEH and peripheralsquamous odontogenic tumor (PSOT) deserve to be a related entity. In two types of mixed POH, ectomesenchymal elements appeared juxtaposed to the squamous lining (gingival cyst-like organoid hamartoma) and ghost cells aggregated in the enamel organ of a microdont (peripheral odontoma). None of POH exhibited continuity with the surface epithelium. CONCLUSION: On the basis of this relatively limitedseries of cases, POH, to conceptualize a uniﬁed histogenetic source, are speculated to arise from the softtissue remnants of dental lamina. Gingival rests of Serres seem to retain the ability to pursue epithelial–ectomesenchymal interactions that are necessary leading to odontoma formation. J Oral Pathol Med (2005) 34: 552–7
Keywords: cyst; dental lamina; ectomesenchyme; gingiva; hamartoma; restsof Serres; tumor
Rare gingival equivalents have been observed for a variety of intraosseous odontogenic tumors and tumorlike conditions. These peripheral odontogenic tumors (POT) exhibit three principal histologic patterns – epithelial, ectomesenchymal, and so-called mixed (1–3). It is now well known that epithelial POT can arise either from the soft-tissue remnants of dentallamina or from the basal layers of surface epithelium (4). There is a copious indirect evidence that POT are directly linked to the rests of Serres (1–4); however, the view that the post-embryonic gingival epithelium retains the residual odontogenic potential is only circumstantial. We herein report our experience with 30 cases of POT and allied lesions, particularly focusing on the salienthistologic features of four diﬀerent types of peripheral odontogenic hamartomas (POH) and one example of peripheral variant of squamous odontogenic tumor (SOT). The results of this study, taken together with a review of the literature, provide additional support that the gingival rests of Serres may be a cogent histogenetic source and are remarkable for their ability to spawn many diﬀerent tumor types.Material and methods
The surgical pathology ﬁles of the three institutions and the personal consultation ﬁles served as sources of material. Files were retrospectively reviewed for POT/ POH during a 34-year period from 1970 to 2004. Only cases in which there was no conﬁrmed evidence of bony involvement were accepted. All specimens were ﬁxed in 10% buﬀered formalin and routinely processed for...