Metastatic neuroendocrine carcinoma often presents as carcinoma of unknown primary. Although most cases display immunohistochemical positivity for neuroendocrine markers, subsets of cases display reduced or negative expression for some of these proteins. The identification of metastatic neuroendocrine carcinomas is even more complicated by the occurrence of unrelated tumor types with focal neuroendocrine differentiation. Our patient was a 74-year-old man of Middle Eastern ethnicity. An initial biopsy of a soft tissue metastasis displayed a neuroendocrine profile indicative of a metastatic neuroendocrine carcinoma, positive for CD56 and synaptophysin, and focally for ISL LIM homeobox 1 and insulinoma-associated protein 1. The Ki-67 index was 50%. Chemotherapy was initiated, but our patient progressed. Scrapings from a pathological hip fracture 3 months later revealed focal synaptophysin immunoreactivity and widespread melanoma antigen, human melanoma black 45, and SOX10 positivity, which are indicative of metastatic malignant melanoma with focal neuroendocrine differentiation. Malignant melanoma may display neuroendocrine differentiation, and the entity should be considered a rare differential diagnosis when assessing biopsies of suspected neuroendocrine carcinomas.

中文翻译：

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伴神经内分泌分化的转移性恶性黑色素瘤一例报告并文献复习


转移性神经内分泌癌通常表现为原发灶不明的癌。尽管大多数病例显示神经内分泌标记物的免疫组织化学阳性，但部分病例显示其中一些蛋白质的表达减少或阴性。由于具有局灶性神经内分泌分化的不相关肿瘤类型的出现，转移性神经内分泌癌的识别变得更加复杂。我们的病人是一位 74 岁的中东裔男性。软组织转移的初始活检显示神经内分泌特征表明转移性神经内分泌癌，CD56 和突触素阳性，局部 ISL LIM 同源框 1 和胰岛素瘤相关蛋白 1。Ki-67 指数为 50%。化疗开始了，但我们的病人病情出现了进展。 3 个月后，病理性髋部骨折的刮片显示局灶性突触素免疫反应性和广泛的黑色素瘤抗原、人黑色素瘤 Black 45 和 SOX10 阳性，这表明患有局灶性神经内分泌分化的转移性恶性黑色素瘤。恶性黑色素瘤可能表现出神经内分泌分化，在评估疑似神经内分泌癌的活检时，应将其视为罕见的鉴别诊断。