David G. Gardner

The peripheral odontogenic fibroma : An attempt at clarification

Three different but probably related central lesions of the jaws have been referred to previously as odontogenic fibromas. They are (1) hyperplastic dental follicles, (2) a fibrous neoplasm having a histologic appearance similar to that of a dental follicle, and (3) a more complicated lesion, illustrated in a WHO publication, consisting of fibrous connective tissue with varying amounts of odontogenic epithelium, dentin, and/or material resembling cementum. The terms simple odontogenic fibroma and odontogenic fibroma (WHO type) are proposed, respectively, for lesions 2 and 3 above. Some examples of lesion 3 may be confused histologically with the calcifying epithelial odontogenic tumor. More information is required on the biologic behavior of both 1 and 2. A central fibroma of the jaws should be considered a desmoplastic fibroma if it does not appear to have arisen from the odontogenic apparatus and is not a neurofibroma.

The treatment of ameloblastoma based on pathologic and anatomic principles.

A number of important factors must be considered in planning the treatment of ameloblastoma. It is essential to distinguish among the three clinical types of ameloblastoma—the intraosseous solid or multicystic lesion, the well‐circumscribed unicystic type, and the rare peripheral (extraosseous) ameloblastoma—because they require different forms of treatment. Unicystic ameloblastomas in which the tumor extends into the lumen of the cyst or involves only the cystic lining can be expected to be removed completely by enucleation. This approach, however, is inadequate if the tumor has invaded the periphery of the fibrous connective tissue wall. Ameloblastomas may invade the intertrabecular spaces of cancellous bone but do not invade compact bone, although they may erode it. Ameloblastomas in the posterior part of the maxilla should be treated more extensively than similar lesions in the mandible because of the proximity of the posterior maxilla to vital structures and the difficulty in treating any recurrences. This article discusses the treatment of ameloblastoma based on these pathologic and anatomic considerations and includes brief discussions of the role of cautery, cryotherapy, and radiotherapy.

A pathologist's approach to the treatment of ameloblastoma

There are three clinical types of ameloblastoma: the solid or multicystic type; the unicystic type; and the rare peripheral type. Important considerations in planning treatment include the clinical type as well as the anatomic location of the tumor and the availability of the patient for follow-up examinations. The various histologic patterns exhibited by this tumor have no bearing on its biologic behavior. In this article the treatment of the three types of ameloblastoma is discussed, with emphasis on their biologic behavior and anatomic considerations.

Peripheral ameloblastoma. A study of 21 cases, including 5 reported as basal cell carcinoma of the gingiva

The peripheral ameloblastoma and the basal cell carcinoma of the gingiva are probably the same lesion. This article describes the clinical features, natural history, and histopathology of nine acceptable cases published as peripheral ameloblastoma, five lesions published as basal cell carcinoma of the gingiva, and seven unpublished cases of peripheral ameloblastoma. Tissue sections were studied from seven of the cases published as peripheral ameloblastoma, three of the cases published as basal carcinoma, and all the unpublished cases. The peripheral ameloblastoma may exhibit several of the various histologic patterns found in the intraosseous ameloblastoma but has a marked tendency to be acanthomatous. These lesions appear to arise from either remnants of the dental lamina within the gingiva or from the surface epithelium. They are relatively innocuous lesions lacking the persistent invasiveness of intraosseous ameloblastoma. Peripheral ameloblastomas should be excised with a small margin of normal tissue and the surgical site re‐examined periodically.

Plexiform unicystic ameloblastoma: A diagnostic problem in dentigerous cysts

A plexiform pattern of epithelial proliferation, which does not exhibit the histologic criteria for ameloblastoma published by Vickers and Gorlin,13 occurs in dentigerous cysts. Some pathologists have diagnosed it as ameloblastoma yet others have considered it to be epithelial hyperplasia. Sections of 19 cases and the limited clinical information available were studied. Histologically characteristic ameloblastoma was found associated with this pattern in nine cases and one case, exhibiting only this pattern, recurred. It is concluded that the pattern in question is in fact ameloblastoma and that Vickers and Gorlins criteria, although valuable, are too rigid for the diagnosis of this plexiform pattern of ameloblastoma in dentigerous cysts. There is need for further study on the natural behavior of these tumors. However, enucleation with good follow‐up examination is probably sufficient for tumors that have proliferated into the cystic lumen, but more extensive surgery is indicated for those involving the periphery of the fibrous connective tissue wall of the cyst. This pattern occurs primarily during the second and third decades of life, generally in the mandible. The term “plexiform unicystic ameloblastoma” is proposed for this lesion to distinguish it from classical plexiform ameloblastoma.

Pseudocysts and retention cysts of the maxillary sinus

The dome-shaped radiopaque shadows frequently seen on the floor of the maxillary sinus, and sometimes inaccurately referred to as antral mucoceles, appear to represent focal accumulation of inflammatory exudate that lifts the epithelial lining of the sinus and the periosteum away from the underlying bone to form the characteristically shaped structures. Their histologic appearance is therefore that of normal or inflamed maxillary sinus lining. There is no epithelium-lined cavity present beneath the sinus mucosa; consequently, the term pseudocyst of the maxillary sinus is advocated. Less commonly, epithelium-lined retention cysts, similar to those of the minor salivary glands, are found, but mucoceles of the type found in the oral cavity apparently do not occur in the maxillary sinus.

The mixed odontogenic tumors

This article attempts to clarify the interrelationships of the so-called mixed odontogenic tumors. The difficulty in distinguishing histologically between the ameloblastic fibroma and the ameloblastic fibro-odontoma on the one hand and the developing odontoma on the other is emphasized. Also discussed is the desirability of discarding some terms used for histologic variants of ameloblastic fibroma, such as immature dentinoma and ameloblastic fibrodentinoma.

Canalicular adenoma: Not a basal cell adenoma

The evidence that canalicular adenomas and basal cell adenomas are separate entities is presented in this article. The clinical features were studied in a series of 13 previously unreported salivary gland tumors (5 canalicular adenomas and 8 basal cell adenomas) and 99 examples derived from the literature (68 canalicular adenomas and 31 basal cell adenomas). Representative tumors from the new cases and from 66 referred cases were studied by histologic, histochemical, and electron microscopic techniques. The two tumors differ significantly with respect to the age range of affected patients, site of predilection, and morphologic and histochemical features.

The relationship of plexiform unicystic ameloblastoma to conventional ameloblastoma

The term plexiform unicystic ameloblastoma refers to a pattern of epithelial proliferation that has been described in cystic lesions of the jaws. It has been considered hyperplastic epithelium, rather than ameloblastoma, by some pathologists because it does not exhibit previously accepted histologic criteria for ameloblastoma. This article provides histologic evidence that plexiform unicystic ameloblastoma is, in fact, a variant of conventional unicystic ameloblastoma by reporting ten cases of unicystic ameloblastoma that exhibit both patterns. Further evidence of the ameloblastomatous nature of plexiform unicystic ameloblastomas is that their biologic behavior, even when this pattern occurs alone, is similar to that of conventional unicystic ameloblastoma.

The use of the termsmonomorphic adenoma, basal cell adenoma, andcanalicular adenoma as applied to salivary gland tumors

There is considerable confusion in the literature concerning the terms monomorphic adenoma, basal cell adenoma, and canalicular adenoma. This article traces the history of these terms as applied to the pathology of salivary gland tumors and attempts to clarify their usage. It is recommended (1) that monomorphic adenoma be used, as it was originally intended, as a nosologic grouping for all benign epithelial salivary gland tumors that are not pleomorphic adenomas, (2) that basal cell adenoma be used to identify a specific entity that is one component of the monomorphic adenoma group and exhibits a number of histologic subtypes, and (3) that canalicular adenoma be used to describe another entity, distinct from basal cell adenomas but also belonging to the monomorphic adenoma group.