Female patient, aged 19 years, who consulted for recurrent mild pain in the left hemimandibula, associated with paraesthesia in the aforementioned area, especially in the lower lip. He also described slight pain on chewing in the molars and premolars on the affected side.
Physical examination revealed a slight facial asymmetry due to an increase in volume located in the most posterior area of the mandibular body and right ascending ramus. The enlargement is painless. Intrabuccally, a bulging external bone table is observed in the area of the second molar. A similar situation, but with expansion of both tables, is detected on palpation of the mandibular ascending ramus. Third molar clinically absent.
With the diagnostic hypothesis of an odontogenic mandibular cyst or odontogenic tumour, an imaging study is requested prior to biopsy. The panoramic X-ray revealed an extensive radiolucent lesion with clear limits, uniloculated and involving the entire ascending mandibular branch. Associated with the lesion, the third molar is observed in a low position and in distoversion.

An incisional biopsy was scheduled during which, according to the clinical characteristics of the lesion, a decompression cannula was installed. The histopathological report revealed an Ackermann type IIIa unicystic ameloblastoma with intramural growth9.

After 10 months of clinical and radiographic follow-up, with the presence of a decompression cannula whose length is gradually reduced, the ameloblastic cystic lesion is almost completely reduced, so enucleation and curettage surgery of the residual cavity is performed, in addition to exodontia of the third molar involved 15.