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