Oral Mucosal Melanoma In Situ Manifesting as Multiple Gingival Macules Around a Dental Implant-Based Prosthesis: A Case Report.

Introduction: Oral malignant melanoma in situ is a rare lesion that may precede the development of invasive oral malignant melanoma. We report an unusual presentation of a rare oral malignant melanoma in situ as multiple gingival macules around a dental implant-supported prosthesis, posing a significant diagnostic challenge. Method: A 68-year-old Caucasian male presented with two black macules on the buccal gingiva of a dental implant and pontic of the implant-based prosthesis; they were asymmetric, with discrete borders, smooth surface, and homogenous color. Two small areas of gray discoloration were also seen on the palatal gingiva. The provisional diagnosis was postinflammatory pigmentation. Results: Following excision of all lesions, an oral mucosal melanoma in situ was diagnosed. A watch-and-wait approach with a 3-month follow-up was decided. Twelve months later, the lesion recurred in the subpontic area, and wide excision on clinically normal margins of the gingival mucosa to the level of periosteum was performed. Conclusions: This case emphasizes that peri-implant pigmentation should not automatically be attributed to inflammatory or implant-related causes. Early biopsy remains essential because oral mucosal melanoma in situ may present deceptively and can recur despite initial complete excision.