Lenders Daniela, Aebischer Valentin, Gassenmaier Maximilian, Hahn Matthias, Metzler Gisela, Forchhammer Stephan
Department of Dermatology, University of Tuebingen, 72076 Tuebingen, Germany.
Dermatopathology Friedrichshafen, 88048 Friedrichshafen, Germany.
Diagnostics (Basel). 2025 Sep 8;15(17):2279. doi: 10.3390/diagnostics15172279.
Nested melanoma is a rare subtype of superficial spreading melanoma. Due to its typical histology, characterized by the predominance of large melanocytic nests in an extensive horizontal spread, it is challenging to distinguish it from other benign nested melanocytic lesions. There is a need to identify additional histopathological parameters that can support the diagnosis of nested melanoma. In this retrospective case-control study, we analyzed immunohistochemical staining for PRAME in 10 cases of superficial spreading melanoma with prominent nests and 26 nested melanomas. Dysplastic melanocytic nevi were used as the control group. We found a diffuse PRAME positivity (>75% of melanocytes) in 60% of superficial spreading melanoma with prominent nests and 19% of nested melanoma cases, whereas the control group showed no diffuse PRAME positivity. Furthermore, using Melan A immunohistochemistry, we found an absence of pagetoid spread in 31% of nested melanoma and single cells in suprabasal epidermal layers in 69% of cases. All cases with no pagetoid spread were PRAME negative, whereas 28% of cases with a mild pagetoid spread demonstrated diffuse PRAME positivity. We found lower PRAME positivity in nested melanoma compared to superficial spreading melanoma with prominent nests. Particularly in cases without pagetoid intraepidermal spread of melanocytes, negative PRAME staining does not rule out the possibility of nested melanoma. The diagnosis should be made based on typical histomorphological and clinical criteria.
巢状黑色素瘤是浅表扩散性黑色素瘤的一种罕见亚型。由于其典型的组织学特征，即大量黑素细胞巢在广泛的水平扩散中占主导地位，因此将其与其他良性巢状黑素细胞病变区分开来具有挑战性。需要确定能够支持巢状黑色素瘤诊断的额外组织病理学参数。在这项回顾性病例对照研究中，我们分析了10例有明显巢状结构的浅表扩散性黑色素瘤和26例巢状黑色素瘤中PRAME的免疫组化染色情况。发育异常性黑素细胞痣作为对照组。我们发现，60%有明显巢状结构的浅表扩散性黑色素瘤和19%的巢状黑色素瘤病例中存在弥漫性PRAME阳性（>75%的黑素细胞），而对照组未显示弥漫性PRAME阳性。此外，通过Melan A免疫组化，我们发现31%的巢状黑色素瘤不存在派杰样扩散，69%的病例在表皮上层有单个细胞。所有无派杰样扩散的病例PRAME均为阴性，而28%有轻度派杰样扩散的病例显示弥漫性PRAME阳性。我们发现，与有明显巢状结构的浅表扩散性黑色素瘤相比，巢状黑色素瘤的PRAME阳性率较低。特别是在黑素细胞无表皮内派杰样扩散的病例中，PRAME染色阴性并不排除巢状黑色素瘤的可能性。诊断应基于典型的组织形态学和临床标准。
