A 52-year-old Caucasian woman had complained of a symptomless swelling in her anterior upper left gingivae facially between the central and lateral incisor for about 2 months.
Oral examination revealed a single sessile, round, cystic-like lesion measuring 1.2 x 2.0 cm, which was not tender but fluctuant and with a bluish colour (Figure 1). There was no discharge or communication of the lesion with the periodontium of the adjacent teeth. Although the central and lateral incisor had cervical caries and exogenous stains, they were vital on pulp testing, and radiography did not show osseous involvement.
Figure 1. A single sessile, round, cystic-like lesion, bluish in colour.
The lesion was removed under local anaesthesia and consisted of a fibrovascular connective tissue with minimal chronic inflammation and was lined in parts by stratified squamous epithelium.
No recurrence was reported during 18 months follow-up.
Q1. What is the probable diagnosis?
Lateral periodontal cyst (LPC);
Parulis;
Peripheral odontogenic keratocyst;
Gingival cyst of adult;
Globulomaxillary cyst.
A1. The answer to what is the probable diagnosis?
Lateral periodontal cyst (LPC) is a relative uncommon odontogenic cyst formed, during odontogenesis, from the epithelial rests of Malassez. This cyst is more often seen in middle-aged males and located between the roots of vital mandibular canines or premolars. It is asymptomatic and can be discovered accidentally by radiographic examination as a round or teardrop-shaped, well-circumscribed radiolucency.
The lateral periodontal cyst shares some characteristics with our lesion, such as the age, the race but not the sex predilection, the absence of symptomatology, same histological features and the good prognosis.
The LPC differs in its location from the lesion shown. Initially it is found within bone but, as the cyst grows, causes bony expansion and perforation, and thus the lesion can finally communicate with the overlying gingivae. In contrast, our lesion was located exclusively in the gingivae and without osseous involvement.
Parulis is common, characterized by a soft erythematous lesion on the gingiva, and made up of inflamed granulation tissue and associated with a non-vital tooth. On pressure, there is typically a pustular or bloody discharge from the lesion while radiography reveals a chronic apical infection. The absence of a non-vital tooth and discharge here rules out that this lesion is a parulis.
Peripheral odontogenic keratocyst is a gingival variation of the odontogenic keratocyst (keratocystic odontogenic tumour) characterized by a lower recurrence and aggressiveness. This cyst is rare and is usually located in the mucosal facial area of the canine-premolar region, but with no significant osseous changes seen during radiographic examination. However, the peripheral and the odontogenic keratocyst lumens are lined by parakeratinized epithelium. This histological finding allows us to exclude our lesion as a peripheral keratinocyst since the epithelium in our lesion is non-keratinized and the inflammation within the connective tissue is minimal.
Gingival cyst of adult is the diagnosis in our case. This is a rare lesion (<0.5% of all cysts) of odontogenic origin and appears as a single, small, asymptomatic swelling with bluish colour on the attached gingivae or interdental papillae adjacent to incisor, canine and premolar teeth. Its cystic sac is composed of fibrous connective tissue with minimal inflammation and is lined by non-keratinized epithelium. This cyst does not cause bone destruction and has a good prognosis.
Globulomaxillary cysts appear between a maxillary incisor (lateral) and the adjacent canine and is characterized by an inverted pear-shaped radiolucency that can sometimes cause diversion of the roots of the adjacent teeth.
