Melanoma is a malignant form of cutaneous cancer with an increasing incidence since 1970s, accounting for nearly 75% of the death related to skin cancer especially in western countries. Highest recurrence and mortality were observed for the subtype with distal metastasis, demonstrating poor outcomes. However, high incidence of gastrointestinal metastasis of malignant melanoma is frequently misdiagnosed due to lack of specific clinical manifestations, especially for the rare observed cases presented amelanotic appearance, accounting for about 2% of all metastatic cases. In the present study, we reported a 36-year-old male patient, who was firstly diagnosed as gastric cancer, and then was confirmed as amelanotic melanoma metastasis by pathological examination, demonstrating positive for melanoma markers including Melan A, S-100, Hmb45 and CD79a. In conclusion, for the amelanotic neoplasm observed during gastroscopy in patients with melanoma history, pathological examination should be carried out to confirm the possibility of melanoma metastasis, providing evidences for the following treatment.

中文翻译：

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无黑色素转移性胃恶性黑色素瘤：病例报告。

黑色素瘤是皮肤癌的一种恶性形式，自 20 世纪 70 年代以来发病率不断上升，占皮肤癌相关死亡人数的近 75%，尤其是在西方国家。远端转移亚型的复发率和死亡率最高，表明预后较差。然而，恶性黑色素瘤胃肠道转移的发生率很高，由于缺乏特异性的临床表现，经常被误诊，尤其是罕见的无黑色素外观病例，约占所有转移病例的2%。在本研究中，我们报道了一名36岁男性患者，最初被诊断为胃癌，随后经病理检查证实为无色素性黑色素瘤转移，其黑色素瘤标志物Melan A、S-100、Hmb45呈阳性。和CD79a。总之，对于有黑色素瘤病史的患者在胃镜检查中发现的无色素性肿瘤，应进行病理检查以确认黑色素瘤转移的可能性，为后续治疗提供依据。