Archegonous cystic odontoma: expanding the spectrum of hybrid odontogenic lesions.

A late adolescent female presented with a progressively enlarging swelling of the right posterior mandible over 5 months. Contrast-enhanced CT demonstrated a well-defined, expansile cystic lesion measuring 3.9×3.2×6.2 cm, with internal calcifications, significant cortical thinning and an associated impacted lower third molar. Given the circumscribed radiographic margins and clinically benign behaviour, complete surgical enucleation under general anaesthesia was undertaken. Histopathological examination revealed a cystic cavity lined by odontogenic epithelium with ameloblast-like basal cells, polarity reversal, stellate reticulum-like zones, ghost cells and foci of mineralised dental tissue consistent with a diagnosis of archegonous cystic odontoma. Postoperative recovery was unremarkable and follow-up at 18 months confirmed complete bony remodelling with no clinical or radiographic evidence of recurrence. This case highlights a diagnostically challenging odontogenic lesion whose nosological position within the broader primordial odontogenic spectrum continues to generate debate and reinforces the need to correlate clinical, radiographic and histopathological data before reaching a definitive diagnosis.