Atypical presentation of lateral periodontal cyst associated with impacted teeth: two case reports

Lateral periodontal cyst (LPC) is an uncommon form of developmental odontogenic cyst. LPC can be suspected when there is a round, well-circumscribed radiolucency, usually of small diameter, along the lateral surface of vital erupted teeth, predominantly in the mandibular premolar region. Histopathological analysis allows LPC to be diagnosed based on its characteristic features such as a thin cuboidal to stratified squamous non-keratinizing epithelium containing epithelial plaques and glycogen-rich clear cells. The aim of this article was to report two cases of atypical LPC associated either with an impacted lower left canine (tooth #33) or with a lower right third molar (tooth #48).

Case 1: A 56-year-old man was referred to us for an oro-dental assessment. Panoramic radiography revealed an impacted lower left permanent canine (tooth #33) with well-defined radiolucency on its upper cervical margin. A CT scan revealed a pericoronal radiolucency of 5 mm at its widest diameter around the impacted tooth #33. The pericoronal tissue was removed and sent for histopathological examination. The results revealed a lateral periodontal cyst. Satisfactory postoperative healing was achieved at the site. Follow-up at 12 months indicated no recurrence of the lesion. Case 2: A 54-year-old woman consulted with the main issue being pain on the lower right side of the face. Intra-oral examination revealed a vestibular swelling involving the region of the second molar (tooth #47), with obliteration of buccal sulcus. Pocket depth was determined to be 9 mm at the distal of #47. A diagnosis of gingival abscess resulting from chronic periodontitis was made. Panoramic radiography revealed a radiolucent cystic lesion associated with an impacted horizontal lower right third molar (tooth #48), suggestive of a dentigerous cyst. X-rays also revealed alveolar bone resorption on the molar (tooth #47). The cyst was removed along with the third molar and submitted for histopathological diagnosis. The diagnosis was LPC. Follow-up at 18 months indicated no recurrence of the lesion.

These cases represent atypical presentations of LPC. They provide examples of the differential diagnosis of pericoronal radiolucencies involving an impacted tooth and our observations provide insights regarding the pathogenesis of LPC.