Peripheral calcifying odontogenic cyst in maxillary anterior gingiva: A case report.

Background: Calcifying odontogenic cysts (Gorlin cysts) most commonly present centrally and have only rarely been reported in peripheral locations. The purpose of this report is to describe a new case of peripheral calcifying odontogenic cyst (PCOC) occurring in the anterior maxillary gingiva and to review the management and differential diagnosis of such a lesion.

Methods: A 37-year-old female presented with a long-standing submucosal nodule on the gingiva between the maxillary central incisors, with asymptomatic growth over the last three years. Following an initial incisional biopsy, a diagnosis of PCOC was established. To exclude the possibility of a central process, a corresponding small field of view cone beam CT scan was obtained and the patient returned for a 6 mm excisional biopsy to the depth of the periosteum.

Results: Results of these additional assessments supported the original diagnosis of PCOC. Following uneventful healing of the second biopsy, no recurrence or other clinical findings were noted at 1-year follow-up.

Conclusion: While rare, the peripheral variant of calcifying odontogenic cyst, and other peripheral counterparts to recognized central cysts and tumors, should be considered in a differential diagnosis for a benign gingival nodule. Gingival tissue should be submitted for histologic evaluation to ensure a neoplastic process is not present.

Key points: Various lesions may present on the gingiva as a "bump"; these can represent common clinical entities, such as pyogenic granuloma, peripheral ossifying fibroma, peripheral giant cell granuloma, and fibroma, or more rare conditions that may not be adequately considered in the differential diagnosis. A rarely documented case of peripheral calcifying odontogenic cyst (PCOC; Gorlin cyst) on the maxillary anterior gingiva of an adult female is reported here and compared with the few other similar PCOC cases in the literature. A biopsy of gingival lesions is always necessary to establish the correct diagnosis and provide the appropriate treatment.

Plain language summary: Several different lesions can appear on the gingiva (gums). Some are quite common, and some are rare. This report documents the occurrence of a new case of calcifying odontogenic cyst (Gorlin cyst), a type of cyst that has been rarely found outside the jawbone, presenting as a "bump" on the gingiva between the maxillary central incisor teeth of an adult female. Because of the patient history, a peripheral calcifying odontogenic cyst (PCOC) was not initially suspected. Following a biopsy, a PCOC diagnosis was given. The possibility of a lesion within the bone was then excluded by an X-ray (cone beam CT) scan examination. A second, more extensive biopsy confirmed the diagnosis and the removal of the lesion. The patient had no complications or recurrence for the following 12 months. This case highlights the need to always biopsy lesions presenting on the gums to obtain a proper diagnosis and provide the correct treatment.