<div>Key clinical message:</div><div>This is the image of dentigerous cyst detected in the medial wall of
maxillary sinus, a rare location for the mentioned cyst, which
emphasizes the superiority of radiographic features from the site of the
lesion. Moreover, the present case showed no facial asymmetry despite
the extension of the lesion.</div><div>Keywords:</div><div>Dentigerous cyst, impacted third molar, maxillary sinus</div><div>Case description:</div><div>A 22-year-old woman was referred to the private radiographic center for
a cone beam computed tomography (CBCT) scan due to a lesion discovered
in a previous panoramic radiography. The patient chief complaint was pus
drainage at the distal portion of upper left last tooth. No facial
asymmetries or other clinical features were identified, and the patient
did not report any other complications including airway obstruction. No
medical history was also reported.</div><div>The evaluation of CBCT scan, including axial, coronal, sagittal and
3-dimensional reconstructed aspects, revealed an extensive lesion
surrounding the coronal part of the impacted ectopic tooth no. 16,
locating in the left maxillary sinus. The border of the lesion was
well-defined and corticated. Double cortex view was visible in coronal,
sagittal and axial aspects. The internal structure of the lesion was
unilocular and radiolucent. However, it was responsible for the opacity
observed in the left maxillary sinus. The dimensions of the lesion were
41 mm vertically, 36 mm antero-posteriorly and 25 mm medio-laterally.</div><div>The lesion displaced tooth no. 16, pushing it towards nasal fossa. It
had also occupied the entire left maxillary sinus, caused displacement
and thinning of the left maxillary sinus walls. Bony perforation was
visible at the distal site of the tooth no. 15, probably responsible for
the pus drainage at the distal portion of tooth no. 15. Additionally,
severe displacement of the medial wall of left maxillary sinus to the
midline with prolapse into the ethmoidal air cells and nasal fossa,
narrowing of left nasal airway, and obstruction of the left maxillary
sinus ostium were visible.</div><div>The lesion was attached to the tooth via cementoenamel junction as seen
in figure 1.</div><div>Among differential diagnoses including unicystic ameloblastoma and
dentigerous cyst, based on these radiographic findings, the diagnosis of
a dentigerous cyst was made. The patient was then referred to an oral
and maxillofacial surgeon for further management of the lesion, which
may include marsupialization or enucleation, as well as pathological
evaluations.</div><div>Dentigerous cyst (DC) also called follicular cyst, is the most common
noninflammatory and also the second most common odontogenic cyst
originating from the reduced enamel epithelium, which is proliferated
due to the osmotic pressure resulting from a fluid filled sac (1, 2). It
is more frequent in males and the incidence of the aforementioned cyst
is approximately 70% in the mandible and its occurrence in the maxilla
is rare (2, 3). In cases with the diagnosis of DC in the maxilla, the
impacted canine is usually the responsible tooth and the diagnosis of DC
involving a maxillary impacted third molar is very rare (3).
Radiographically, DC is a radiolucent lesion, presenting either
unilocular or scalloping multilocular pattern (2). The important
diagnostic key is the engagement of the cyst’s well-defined and
corticated periphery to the cementoenamel junction of the involved tooth
(1).</div><div>Author contributions</div><div>Maryam Mohebiniya: Conceptualization, investigation, project
administration, supervision, visualization, writing – review &amp;
editing. Soheila Jadidi: writing – original draft, writing – review &amp;
editing.</div><div>Conflict of interests</div><div>None</div><div>Declaration of patient consent</div><div>The patient has given her consent for her clinical information to be
reported in the journal.</div><div>Acknowledgment</div><div>None</div><div>References</div><div>1. Sanjay Mallya EL. White and Pharoah’s Oral Radiology. 8th ed2018.</div><div>2. Motamedi MHK, Talesh KT. Management of extensive dentigerous cysts.
British Dental Journal. 2005;198(4):203-6.</div><div>3. Asnani S, Mahindra U, Rudagi B, Kini Y, Kharkar V. Dentigerous cyst
with an impacted third molar obliterating complete maxillary sinus:
Official Publication of Indian Society for Dental Research. Indian
Journal of Dental Research. 2012;23(6):833-5.</div><div>Figure Legends</div><div>Figure 1: (a) axial and (b) coronal CBCT scan revealing an extensive
lesion surrounding the coronal part of the impacted ectopic tooth no.
16, locating in the left maxillary sinus. Note the attachment of the
lesion to the tooth via cementoenamel junction.</div>