A dark, blue-grey lesion is present in the cervical and palatal area adjacent to the maxillary first molar. It resembles an amalgam tattoo, but NO radiopacity is visible on the radiograph. What is the appropriate concern?

Correct answer: C. A melanocytic lesion, including melanoma, must be excluded by biopsy

• A. Physiologic pigmentation is symmetrical, DIFFUSE, bilateral, typically on the attached gingiva, present since youth and stable. A solitary focal lesion does not fit.
• B. Only a minority of amalgam tattoos actually show radiopaque particles — small or finely dispersed particles are radiographically invisible — so a negative radiograph does not exclude tattoo. But it also does not confirm it, and 'certainly' is not a defensible clinical position for a pigmented palatal lesion.
• C. CORRECT. The absence of radiopacity removes the one finding that would have made amalgam tattoo a confident clinical diagnosis. A pigmented lesion of the PALATE or MAXILLARY GINGIVA in an adult — precisely the sites where oral MELANOMA is most common (the hard palate and maxillary alveolar gingiva account for the large majority of cases) — must be regarded as suspicious until proven otherwise. BIOPSY is mandatory. Oral melanoma is rare but is diagnosed late and carries a dismal prognosis, largely because early lesions are flat, painless and dismissed as tattoos or physiologic pigment.
• D. A haematoma would follow identifiable trauma, would be tender initially, and would change colour and resolve over one to two weeks. A persistent lesion is not a haematoma.

Note: The decision rule for oral pigmentation: biopsy any pigmented lesion that is SOLITARY, on the palate or maxillary gingiva, of recent onset, changing in size or colour, ulcerated, or of uncertain aetiology. A definite history of restorative treatment in the exact site with corresponding radiopaque particles is the only situation in which observation alone is reasonable.