{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,7]],"date-time":"2026-08-07T16:49:42Z","timestamp":1786121382836,"version":"build-2736575974"},"reference-count":27,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2026,8,4]],"date-time":"2026-08-04T00:00:00Z","timestamp":1785801600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J. Clin. Med.","JCM"],"abstract":"<jats:p>Malignant melanoma demonstrates strikingly varied clinical presentations, on account of which it is often challenging to diagnose. We describe herein a rare case of amelanotic malignant melanoma (AMM) in the buccinator muscle presenting as a solitary mass. A middle-aged woman presented with a non-pigmented swelling under the right buccal mucosa. Magnetic resonance imaging (MRI) revealed a well-circumscribed lesion without local invasion. A needle biopsy did not establish the diagnosis and was instead interpreted as suggestive of a salivary gland tumor, reinforcing an initial impression of myoepithelioma. Histopathological analysis of an excised specimen revealed poorly defined, pleomorphic tumor cells and a scattering of melanin-containing cells. The diagnosis of AMM was established by integrating these histopathological features with the clinico-radiological findings and the immunohistochemical results, which were positive for HMB-45, S-100, and SOX10 and negative for cytokeratin. Whole-body positron-emission tomography-computed tomography found no primary lesion. Because tumor nests suggesting possible residual disease were observed near the resection margin, a wider, secondary excision including the affected portion of the buccal mucosa and overlying skin was performed together with neck dissection. Histopathological examination of the re-resection specimen showed no residual tumor, indicating that no malignant cells were identified in the adjacent oral mucosa or facial skin. The patient has remained disease-free for three years.<\/jats:p>","DOI":"10.3390\/jcm15156075","type":"journal-article","created":{"date-parts":[[2026,8,4]],"date-time":"2026-08-04T15:08:09Z","timestamp":1785856089000},"page":"6075","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["A Rare Case of Amelanotic Melanoma with an Unknown Primary in the Buccinator Muscle"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0711-9886","authenticated-orcid":false,"given":"Yusuke","family":"Matsuzaki","sequence":"first","affiliation":[{"name":"Department of Oral and Maxillofacial Surgery, Tokyo Dental College, 2-9-18 Kanda-Misakicho, Chiyoda-ku, Tokyo 101-0061, Japan"},{"name":"Department of Dentistry and Oral Surgery, Tokyo Metropolitan Tama Medical Center, 2-8-29 Musashidai, Fuchu-shi, Tokyo 183-8524, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rei","family":"Nishiyama","sequence":"additional","affiliation":[{"name":"Department of Dentistry and Oral Surgery, Tokyo Metropolitan Tama Medical Center, 2-8-29 Musashidai, Fuchu-shi, Tokyo 183-8524, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6405-4276","authenticated-orcid":false,"given":"Yukio","family":"Watabe","sequence":"additional","affiliation":[{"name":"Department of Dentistry and Oral Surgery, Tokyo Metropolitan Tama Medical Center, 2-8-29 Musashidai, Fuchu-shi, Tokyo 183-8524, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Akira","family":"Watanabe","sequence":"additional","affiliation":[{"name":"Department of Oral and Maxillofacial Surgery, Tokyo Dental College, 2-9-18 Kanda-Misakicho, Chiyoda-ku, Tokyo 101-0061, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"631","DOI":"10.4103\/0019-5154.143569","article-title":"Amelanotic melanoma masquerading as a superficial small round cell tumor: A diagnostic challenge","volume":"59","author":"Shetty","year":"2014","journal-title":"Indian J. 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