Bilateral Radiolucencies of the Posterior Mandible :
A Clinicopathologic Review
Figure 4 : A panoramic radiograph with bilateral , well-circumscribed , unilocular radiolucencies in the posterior mandible which extends close to the inferior alveolar nerve . They are associated with the crowns of developing third molars . This patient has Gorlin Syndrome as the lesions are histologically keratocystic odontogenic tumors .
The recurrence rate is 1-2 percent in most studies ; however , a rate of recurrence of up to 27 percent has been noted . 1 It is advisable to follow-up patients periodically to confirm bone fill in the area . In the case above , IBC was considered highly in the differential diagnosis , given its predilection to occur in the molar-premolar area of the posterior mandible . 9 The bilaterality , location of the defect below the IANC , and lack of the scalloping around the roots of the teeth placed IBC lower on the differential .
D . Keratocystic odontogenic tumor ( KCOT ) is a benign , odontogenic lesion that is locally-aggressive and destructive . A predilection for the posterior mandible ( 65-83 percent ) is seen , specifically in the area of the angle of the mandible . 1 Radiographically , the lesion can range from a small , well-circumscribed , unilocular lesion to large , multilocular lesions with anterio-posterior expansion . 10 The margins can be sclerotic or diffuse , with or without tooth displacement . Clinically , the lesion usually presents asymptomatically , but may present with pain , swelling and discharge . Multiple KCOTs are seen in patients with Nevoid Basal Cell Carcinoma Syndrome also known as Gorlin syndrome . An example of a case of Gorlin syndrome is provided for comparison ( Figure 4 ). Gorlin syndrome is associated with PTCH gene mutations . Syndromic patients typically present at a young age with features including multiple basal cell carcinomas , epidermal cysts , palmar / plantar pitting , and calcified falx cerebri . 90 % of syndromic patients present with multiple jaw lesions . 1 Confirmation of the lesions are done through biopsy . Histologically , the lesion consists of a 5 to 8 cell layer , corrugated , parakeratinized , friable cystic lining with underlying fibrous connective tissue with or without inflammation . This lesion has a recurrence rate that ranges from 5-62 %, and complete removal is often difficult with enucleation alone . 1 Treatment involves enucleation with peripheral ostectomy of the bony cavity or application of Carnoy ’ s solution for chemical cauterization . 11 Complete excision will result in increased radiographic opacity in the area of the lesion , as bone begins to fill in the area . Due to the high recurrence rate , close clinical and radiographic monitoring for at least five years is warranted . KCOT was considered in the differential in this case given the radiographic presentation of multiple well-circumscribed radiolucent lesions in the posterior mandible . However , the presence of the lesions below the IANC with no effect on adjacent structures and the absence of any other features of Gorlin syndrome is more consistent with SD .
32 JANUARY / FEBRUARY 2017 | PENNSYLVANIA DENTAL JOURNAL