A small, well-circumscribed, dark blue-black lesion is noted on the posterior maxillary alveolar mucosa near a previously restored tooth. Radiographically it shows a small radiopacity. What is the most likely diagnosis?

Correct answer: A. Amalgam tattoo (foreign body)

• A. CORRECT. An amalgam tattoo is the most common pigmented lesion of the oral mucosa. It appears as a flat, blue-gray or black macule adjacent to a restored tooth. Crucially, it may show small radiopaque particles on radiograph (amalgam fragments). The history of dental restoration and radiographic finding confirm the diagnosis.
• B. Oral melanoma is aggressive, typically asymmetric, and irregular. It would not show radiographic metallic particles.
• C. Melanocytic nevus is possible in the oral cavity but is much less common than amalgam tattoo. It does not show radiographic radiopacity.
• D. Focal melanosis (physiologic pigmentation) appears as a flat brown macule without association to restorations and without any radiographic finding.