Sub-populations of melanocytes in pigmented basal cell carcinoma

色素沉着是日本基底细胞癌患者的典型临床特征。色素性基底细胞癌中黑色素的发病机制知之甚少。我们结合形态学分析和电子显微镜技术，准确评估色素性基底细胞癌的色素性和非色素性区域的黑素细胞的形态学方面。色素性区域的黑素细胞不仅位于沿着基底膜，但也散布在肿瘤细胞之间的中央部分的肿瘤巢，并有大量的树突。在非色素区，黑素细胞仅位于基底部，树突较少，且常出现败育的黑素小体;超微结构细胞形态计量学分析显示，两组黑素细胞核和细胞面积、核/细胞面积比、核/细胞面积比、核/细胞这两种类型的黑素细胞之间的细胞形态和细胞形状因子。特别是黑色素细胞的色素沉着领域的两倍，后者的细胞大小。此外，黑素体几乎完全保留在凋亡的肿瘤细胞中，并且含有黑素体的Aparctot细胞被邻近的肿瘤细胞吞噬后，黑素体复合物似乎随之形成。这些发现表明，不同的黑素细胞群体可能存在于色素性基底细胞癌中，并且含黑素体的凋亡细胞的吞噬作用的重复循环可能代表形成大的黑素体复合物的主要方式。本文的形态学观察和定量分析为进一步研究色素性基底细胞癌的其他病理改变提供了形态学基础。

Pigmentation is a characteristic clinical feature of basal cell carcinomas in Japanese patients. The pathogenesis of melanin pigment in pigmented basal cell carcinomas is poorly understood. We have combined the techniques of morphometric analysis and electron microscopy to assess accurately the morphologic aspects of melanocytes that occurred in pigmented and non-pigmented areas of pigmented basal cell carcinomas.n the pigmented areas melanocytes were not only located along the basal membrane but also interspersed between tumor cells in the central parts of the tumor nest, and had large and numerous dendrites. In the non-pigmented areas melanocytes were only basally located, showed fewer dendrites, and frequently showed abortive melanosomes ; However, melanocytes in these two different portions were in the active state of melanogenesis and proliferation.Ultrastructural cytomorphometric analysis also showed significant differences in most of the nuclear and cell parameters including nuclear and cell area, the nuclear/cell area ratio, cell perimete and cell form factor between these two types of melanocytes. Particularly melanocytes in the pigmented areas were twice the cell size of the latter. In addition, the melanosomes remained almost completely in the apoptotic tumor cells, and the phagocytosis of the melanosome-containing apoptot cells by the neighboring tumor cells appeared to be followed by the formation of the melanosome complexes.These findings suggest that different populations of melanocytes are probably present in pigmented basal cell carcinomas, and repeated cycles of phagocytosis of melanosome-containing apoptotic cells may represent the predominant way of forming large melanosome complexes. The present morphological observation and quantitative analysis provide a morphological basis for furthe studies to interpret other pathologic changes in pigmented basal cell carcinomas.