Nakamura Toshitsugu
Department of Diagnostic Pathology, Suwa Red Cross Hospital, Suwa, Japan.
Dermatopathology (Basel). 2018 Jul 19;5(3):86-97. doi: 10.1159/000490491. eCollection 2018 Jul-Sep.
Shadow cells are characterized by an eosinophilic cytoplasm and a ghost-like nuclear contour; the cell shape is preserved, in spite of nuclear disappearance. Shadow cell nests (SCNs) are frequently observed in pilomatricoma (PMX), where the transitional cells immediately adjacent to SCNs often have a crescent-shaped nucleus showing fragmentation similar to that of apoptotic bodies. They show nuclear accumulation of beta-catenin and DNA double strand breaks (as revealed by in situ 3'-tailing reaction or immunohistochemistry for single-stranded DNA [ssDNA]), while they are negative for cleaved caspase-3 or cleaved lamin A, suggesting that shadow cell differentiation (SCD) is a caspase-independent programmed cell death. SCD can be differentiated from epidermal keratinization (EK) and trichilemmal keratinization (TK) based on the expression pattern of beta-catenin, ssDNA, and caspase-14/CD138. SCD is observed not only in PMX, but also sometimes in basal cell carcinomas, gonadal teratomas, and various extra-cutaneous carcinomas. In particular, SCNs are found in 24$ of endometrial adenoacanthoma and are derived from squamoid morules. This establishes a link between basaloid cells in PMX and squamoid morules in endometrial adenoacanthomas as common precursors of shadow cells. Overall, it is suggested that SCD is different from, but partly similar to, apoptosis and that SCD and EK/TK should be differentiated from the standpoint of cell death/differentiation.
影子细胞的特征是嗜酸性细胞质和幽灵般的核轮廓；尽管细胞核消失，但细胞形状得以保留。影子细胞巢（SCNs）在毛母质瘤（PMX）中经常观察到，紧邻SCNs的过渡细胞通常有一个新月形细胞核，显示出与凋亡小体相似的碎片化。它们显示β-连环蛋白的核积累和DNA双链断裂（通过原位3'-末端加尾反应或单链DNA [ssDNA]免疫组织化学显示），而它们对裂解的半胱天冬酶-3或裂解的核纤层蛋白A呈阴性，这表明影子细胞分化（SCD）是一种不依赖半胱天冬酶的程序性细胞死亡。基于β-连环蛋白、ssDNA和半胱天冬酶-14/CD138的表达模式，SCD可与表皮角化（EK）和毛透明角化（TK）区分开来。SCD不仅在PMX中观察到，有时也在基底细胞癌、性腺畸胎瘤和各种皮肤外癌中观察到。特别是，SCNs在24%的子宫内膜腺棘皮瘤中发现，并且来源于鳞状小体。这在PMX中的基底样细胞和子宫内膜腺棘皮瘤中的鳞状小体之间建立了联系，它们是影子细胞的共同前体。总体而言，提示SCD不同于但部分类似于凋亡，并且SCD和EK/TK应从细胞死亡/分化的角度进行区分。
