Botryoid odontogenic cyst developing from lateral periodontal cyst: A rare case and review on pathogenesis
A 20 year-old female reported at our college of dentistry with an extra-oral swelling of lower anterior mandible of 3-4 month duration. Clinical inspection revealed a well circumscribed swelling of 2 × 2 cm size on left lower canine-premolar region obliterating the buccal vestibule []. Panoramic radiograph showed a well-corticated unilocular radiolucency between left canine and first premolar, extending beyond inter-radicular area []. Displacement of adjacent roots is seen. Based on this data, the differential diagnosis of an odontogenic cyst or tumor was made.\nAspiration content showed presence of cholesterol crystals [] and protein content above 5 gms per 100 ml. Incisional biopsy was reported to be LPC as the sections from the specimen showed a cystic lumen lined by 2-3 layers of flattened epithelial cells resembling reduced enamel epithelium. Although a diagnosis of LPC was made, this case appeared rare because of large size of the cyst extending beyond the lateral aspect of the associated premolar and also because the cyst had enlarged to the current size over a period of 3 months only, proving it to be more aggressive than usual LPCs. Based on this, enucleation was performed along with associated premolar. A gross specimen of about 1.5 cms in diameter and firm in consistency was obtained in-toto attached to lateral border of premolar []. Cross-sectioning of specimen revealed a cystic lumen with infoldings at places and nodular growths protruding within lumen. Histopathologic analysis reveals a cystic space lined by thin epithelial layer of 1-4 cell layer thickness. The epithelial lining is non-keratinizing and showed squamous to cuboidal to flattened cells which resemble reduced enamel epithelium. Cyst lining shows epithelial extensions of basal cells ‘raining down’ into connective tissue []. Connective tissue is fibrous, un-inflamed and shows presence of odontogenic epithelial rests. The epithelial cells in the lining show small pyknotic nuclei. Cells are separated by intercellular fluid at places.\nThe lining shows epithelial plaques producing a mural bulge within lumen along with areas of hemorrhage. The mural growths show numerous intra-epithelial microcyst formations. The cells in plaque are fusiform while few cells are round, large and clear with pyknotic nuclei.\nComplex convulations of epithelium, mural proliferations and presence of daughter cysts within the lining shows the tendency of multi-locularity []. The case shows definite botryoid odontogenic changes in lining epithelium of LPC. Hence a final diagnosis of botryoid Odontogenic cyst is made. Special staining was performed and the epithelial lining of the BOC was found to be PAS negative [].\nThe patient was reviewed after 2 months and she showed uneventful recovery.