A periapical/panoramic radiograph shows a well-defined radiolucent area in the posterior maxilla above the premolar/molar apices with a thin corticated border. This most likely represents:

Correct answer: A. Normal maxillary sinus anatomy

• A. Correct. The maxillary sinus normally appears as a well-defined radiolucency above the posterior maxillary teeth; recognizing normal anatomy avoids misdiagnosing it as pathology.
• B. A periapical cyst is centered on a non-vital tooth apex, not the broad sinus space.
• C. A residual cyst remains after extraction at the former apex.
• D. An OKC has a different, often multilocular/scalloped presentation, frequently in the posterior mandible.