A Pigmented Lesion of the Mandibular Facial Gingiva

History of Present Illness

The patient had been aware of the lesion for approximately two years and stated that it may be increasing in size. No pain or other symptoms were associated with the lesion. The patient denied any history of previous oral lesions or recent dental treatment

Past Medical History

The patient’s medical history was significant for three separate, primary skin melanomas that had been diagnosed and treated two to three years earlier. The melanoma that was identified first was located on his nose and treated by wide excision followed by reconstruction by means of a forehead flap. Shortly thereafter, two other primary melanomas were discovered on the skin of his back and were excised. The patient also had a history of hypertension, shortness of breath, and elevated cholesterol. He reported an allergy to penicillin and a history of cigarette smoking. His daily medications consisted of aspirin (81 mg), atorvastatin calcium (Lipitor), and metoprolol succinate (Toprol).

Clinical and Radiographic Findings

Extraoral examination showed evidence of a skin graft on the nose secondary to excision of the previous melanoma. Intraorally, a well-defined brown macule was noted on the facial attached gingiva between teeth #22 and #23 (Figure 1).

demarcated brown macule
Figure 1. A demarcated brown macule on the facial attached gingiva between #22 and #23.

The lesion was 4 mm in diameter and had uniform pigmentation. Periapical radiographs of the area were unremarkable, showing a normal trabecular pattern and no evidence of bone loss.

Histopathologic Findings

Microscopic examination of the biopsy specimen showed a normal maturation pattern of the epithelium with unremarkable rete ridge architecture. A prominent amount of melanin was localized to the basal and parabasal layers of the surface epithelium (Figure 2). Melanin could also be identified within melanophages in the superficial connective tissue (Figure 3). No melanocytic hyperplasia or atypia was seen.

oral epithelium with melanin pigment
Figure 2. This low-power photomicrograph shows normal surface oral epithelium with melanin pigment concentrated at the tips of the epithelial rete ridges and within the superficial connective tissue (hematoxylin and eosin).
partially ulcerated squamous cells
Figure 3. This high-power photomicrograph shows melanin pigment localized to the basal keratinocytes of the epithelium and within melanophages in the underlying connective tissue (hematoxylin and eosin).