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References

Philipsen HP, Reichart PA Classification of odontogenic tumours. A historical review. J Oral Pathol Med. 2006; 35:525-529
Veena KM, Rao Rekha, Jagadishchandra H, Kumar Rao Prasanna Odontogenic keratocyst looks can be deceptive, causing endodontic misdiagnosis. Case Rep Pathol. 2011;
Mufeed A, Vengal M, Issac JK, Vazhagan V, Noufal A Keratocystic odontogenic tumour occurring in the anterior mandible. Annals Medicus. 2014; 1:30-37
Morgan TA, Burton CC, Qian F A retrospective review of treatment of the odontogenic keratocyst. J Oral Maxillofac Surg. 2005; 63:635-639
Grasmuck EA, Nelson BL Keratocystic odontogenic tumour. Head Neck Pathol. 2010; 4:94-96
Rajkumar GC, Hemalatha M, Shsikala R, Sonal P Massive keratocystic odontogenic tumour of mandible: a case report and review of literature. Ind J Dent Res. 2011; 22
Sumer AP, Sumer M, Celenk P, Danaci M, Gunhan O Keratocystic odontogenic tumour: case report with CT and ultrasonography findings. Imaging Sci Dent. 2012; 42:61-64
Bojan A, Duraiselvi P, Sumathy C, Mithra R Odontogenic keratocyst simulating lateral periodontal cyst: a case report. Int J Adv Hlth Sci. 2015; 2:1-4
Scholl RJ, Kellett HM, Neumann DP, Lurie AG Cysts and cystic lesions of the mandible: clinical and radiologichistopathologic review. Radiographics. 1999; 19:1107-1124
Morgan TA, Burton CC, Qian F A retrospective review of treatment of the odontogenic keratocyst. J Oral Maxillofac Surg. 2005; 63:635-639

A case report of an unusual presentation of a keratocystic odontogenic tumour in the anterior mandible

From Volume 43, Issue 9, November 2016 | Pages 891-893

Authors

Vathana Ketheeswaranathan

University Hospital

Articles by Vathana Ketheeswaranathan

Renu George

University Hospital

Articles by Renu George

Manisali Croydon

University Hospital

Articles by Manisali Croydon

Article

Keratocystic odontogenic tumours (KCOTs) are commonly seen in the posterior mandible. They can also rarely occur in the anterior mandible and mimic a lateral periodontal cyst (LPC). Intrabony pathology is rarely seen in the anterior mandible and unilocular appearance is even rarer. We present a case report of a KCOT of the anterior mandible which appeared in the plain radiographs as a unilocular radiolucency and clinically resembled a lateral periodontal cyst.

Case report

A 23-year-old male patient was referred to the Department of Oral and Maxillofacial Surgery by the GDP with a swelling in the lower right lateral incisor and lower right canine region with a duration of 3 weeks. The patient was asymptomatic. Clinical examination revealed a 1 cm diameter fluctuant swelling in the attached gingivae of the LR2 and LR3 extending into the labial/buccal sulcus and obliterating the sulcus. Mucosa overlying the swelling looked normal in colour. LR2 and LR3 were vital for ethyl chloride pulp testing.

An intra-oral periapical radiograph (Figure 1) revealed a well-defined, pear-shaped radiolucency in the interdental region of LR2 and LR3 with a sclerotic margin. The lesion had displaced the roots of the LR2 and LR3 but there wasn't any root resorption seen either on LR2 or LR3.

Figure 1. An intra-oral periapical radiograph taken pre-operatively showing well-demarcated, pear-shaped radiolucency.

A provisional diagnosis of lateral periodontal cyst was made and a differential diagnosis of odontogenic keratocyst, unicystic ameloblastoma and central giant cell granuloma were also made.

The cyst was enucleated completely and the cavity was curretaged under local anaesthesia. The specimen was sent for histopathological examination.

Histopathology examination revealed cystic lumen with corrugated parakeratinized squamous epithelium and palisading of basal nuclei. The features are those of a KCOT (Figure 2a, b).

Figure 2. (a, b) Histology of the cystic lumen showing corrugated parakeratinized squamous epithelium.

The patient was asymptomatic after 6 months of the surgery. A perapical radiograph taken on review revealed good bony healing. LR3 had also moved back into place (Figure 3).

Figure 3. A periapical radiograph taken postoperatively showing good bony healing. LR3 has moved back into its original place.

Discussion

A keratocystic odontogenic tumour (KCOT) was initially described as a primordial cyst as it was thought that the cyst was originating from the tooth primordium. In 1965, Philipsen described the primordial cyst as an ‘Odontogenic Keratocyst’ (OKC).1,2,3 Owing to its neoplastic nature, aggressive behaviour and high recurrence rate, in 2005 the WHO has renamed the OKC as the 'Keratocystic Odontogenic Tumour (KCOT) ‘and defined it as ‘a benign uni- or multicystic, intraosseous tumour of odontogenic origin, with characteristic lining of parakeratinized stratified squamous epithelium and potential for aggressive infiltrative behaviour’.2,3,4,5,6,7,8 Of all jaw cysts, 11% are KCOTs. Although KCOTs are commonly seen in the posterior mandible, they can also rarely occur in the anterior mandible. Theories say that KCOTs develop from the cell rests of dental lamina dura.3,5 Most KCOTs are seen in males (2:1)6 with the age predilection of either 30 or 60.2,5 They can either present as an asymptomatic swelling, as in our case, or a swelling of the jaw with pain. Seldom are they diagnosed as an incidental finding during a routine radiographic examination.

In plain radiographs, the KCOTs appear as either unilocular cysts with well demarcated margins, or as multilocular cysts.2,5,9 It is not uncommon to see the tumour causing root resorption of the adjacent teeth or displacing the adjacent roots, causing divergence of the roots.5

Histopathological features of a KCOT is classic with a thin lining of epithelium consisting of parakeratinized cells or orthokeratinized cells.5 A parakeratinized variant is more frequently seen and clinically has more aggressive behaviour than an orthokeratinized type.8 The cyst lining has a corrugated appearance which makes the tumour incompletely enucleated and gives rise to a high recurrence rate (13–60%).6 The cyst lining is also separated from the supporting connective tissue in many places and the cyst lumen is filled with keratinous material.

Treatment of a KCOT includes enucleation of the cystic lining and curetting the cavity, enucleation with Carnoys solution and ostectomy.5,9,10 Carnoys solution contains chloroform which has been classified as a carcinogen. Recently, the Food and Drug Association US (FDA) has banned therapeutic agents containing chloroform (Jordan Ecker, 2014).

High recurrence rate of KCOT is not only due to surgical difficulty in enucleating the cyst lining completely because of its corrugated appearance and the friability of the epithelium, but is also due to retention of daughter cells post-surgically.6

Multiple KCOT with nevoid basal cell carcinoma and bifid ribs are seen in basal cell naevus syndrome.5,7,9

This case report highlights the importance of early recognition of a KCOT, which can also clinically and radiographically present as lateral periodontal cyst. KCOT should be included in the differential diagnosis of the interdental radiolucency.1 A KCOT in the interdental area of lower canines can often be misdiagnosed as lateral periodontal cyst, which is also commonly seen in this region. As KCOTs are one of the aggressive odontogenic cysts, careful clinical and radiological follow-up is essential for early recognition of recurrence.