Adenomatoid odontogenic tumours (AOT) are uncommon odontogenic lesions characterized histologi-cally by duct-like structures derived from the epithelial component of the lesion and can be distinctly classified into follicular, extrafollicular and extraosseous variants (Neville BW, Damm DD, Allen CM, et al. Adenomatoid Odontogenic Tumor. A Text Book for Oral and Maxillofacial Pathology, 2(nd) edition, 621-3). Most of these tumours develop in the second or third decade of life and have a distinct predilection for women. The follicular variant accounts for 75% of reported cases (Curran AE, Miller EJ, Murrah VA. Adenomatoid odontogenic tumor presenting as periapical disease. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1997;84:557-60) and is associated with the crown of an impacted tooth, commonly the maxillary canine. We present a rare case of extrafollicular AOT mimicking a periapical cyst that originated in a woman in her first trimester of pregnancy and enlarged rapidly thereafter. The lesion was enucleated and sent for histopathology and immunohistochemistry, which revealed AOT with a cystic component with no dependence on oestrogen or progestrone for its growth. This case of AOT introduces us to the unique variation in its presentation and the difficulty in differentiation from periapical disease of inflammatory origin.