During the extraoral assessment with palpable lymph nodes, which radiographic finding would be attributed to the cause?

• A. Interproximal bone loss at #3
• B. Radiolucency at apex of root #10
• C. Widened PDL space at #14
• D. Alveolar crest resorption

Answer: (B)

When a patient has extraoral lymph node enlargement related to a dental source, the radiographic clue points to a periapical inflammatory lesion at the root apex, reflecting an infection from a non-vital pulp. This apical radiolucency represents bone destruction around the tooth tip caused by the inflammatory process, which is a common odontogenic driver of regional lymphadenopathy. Other findings describe bone loss patterns not specific to a focal periapical infection—interproximal bone loss suggests periodontal disease, widened PDL space can occur with trauma or early inflammatory changes but isn’t the classic sign of a periapical source, and alveolar crest resorption indicates broader alveolar bone loss from periodontal disease rather than a localized periapical infection. Thus, the apical radiolucency best explains the cause of the palpable lymph nodes.