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178:Primary Oral Mucosal Melanoma Mimicking An Amalgam Tattoo: Diagnostic Pitfalls[AAOM2021]
EP36061
Poster Title: 178:Primary Oral Mucosal Melanoma Mimicking An Amalgam Tattoo: Diagnostic Pitfalls[AAOM2021]
Submitted on 29 Mar 2021
Author(s): Marlon Moldez1, Daniel O’Connell2, Pallavi Parashar3
Affiliations: 1: Resident - Oral Medicine, Faculty of Medicine & Dentistry, University of Alberta; 2: Associate Professor - Division of Otolaryngology, Head & Neck Surgery, University of Alberta; 3: Associate Clinical Professor - Oral Medicine & Pathology, Faculty of Medicine & Dentistry, University of Alberta
This poster was presented at 2021 American Academy of Oral Medicine Virtual Conference
Poster Views: 125
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Poster Information
Abstract: Background

Mucosal melanomas of the oral cavity (OMM) are extremely rare, accounting for 0.2% to 8.0% of all malignant melanomas, and 0.5% of all malignancies affecting the oral cavity. The hard palate and gingiva are most commonly affected. OMM may frequently mimic several benign entities, both clinically and histopathologically, especially in the early stage. Early diagnosis and treatment are therefore critical since OMM are associated with a poor prognosis due to their invasive and metastasizing tendencies. Here we present a challenging case of primary OMM mimicking an amalgam tattoo clinically.

Case summary

A 68-year-old Caucasian male with a past medical history of prostate cancer presented for assessment of asymptomatic palatal pigmentations of 4-year duration. Irregular greyish-black smooth pigmented macules were identified along the palatal marginal mucosa of teeth # 23, 24, and palatal and buccal interdental papilla of teeth # 22, 21, and 11. Tooth # 24 displayed a large amalgam restoration, and teeth # 21, 11 had full coverage crowns. A clinical diagnosis of amalgam tattoo was considered, given the proximity of these pigmentations with dental restorations. A biopsy of the interdental palatal mucosa in the area of tooth # 23 however revealed invasive atypical pleomorphic melanocytes with a positive expression for human melanoma black 45, consistent with mucosal melanoma. The patient was referred to a Head and Neck surgeon for wider excision of the affected mucosa. A PET-CT scan did not reveal any regional or distant FDG avid lesions, confirming the primary origin of OMM.

Conclusion

Intraoral pigmentations are common and can have numerous etiologies, ranging from exogenous to physiological to neoplastic. Although OMM are extremely rare, the development of an appropriate differential diagnosis is imperative for the timely management of patients with oral pigmentations of neoplastic origin. Misdiagnosis of OMM will have adverse management and prognostic implications.
Summary: A challenging case of primary OMM mimicking an amalgam tattoo clinically is presented.

Ask the author questions about this poster:mmoldez@ualberta.ca
References: 1. Neville B et al, Oral and Maxillofacial Pathology, 4th Edition
2. Chae YS et al, Survival of oral mucosal melanoma according to treatment, tumour resection margin, and metastases, Br J Oral Maxillofac Surg. 2020 Nov;58(9): 1097 – 1102.
3. Mihajlovic M et al, Primary mucosal melanomas: a comprehensive review, Int J Clin Exp Pathol. 2021;5(8):739-53.
4. Patrick RJ et al, Primary mucosal melanoma, J Am Acad Dematol. 2007 May 56(5): 828-34
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