A panoramic radiograph shows a radiopaque well-circumscribed mass at the angle of the mandible that suggests a calcified structure. Among the differential diagnoses, which finding is MOST radiographically opaque and is a normal anatomic structure?

Correct answer: C. Exostosis

• A. Lymph node calcification is possible in this region but is pathologic.
• B. A sialolith is associated with salivary gland ducts and is radiopaque but found in duct locations.
• C. Correct. An exostosis (cortical bone outgrowth) is a radiopaque bony prominence that appears as a well-defined radiopaque structure. When asked which of the listed differential diagnoses is the only radiopaque (vs. radiolucent) finding in a photo/X-ray scenario, exostosis is the answer as it is purely bony (most opaque).
• D. A tonsillolith appears in the tonsillar region — not at the mandibular angle.