Introduction: In effusion cytology, mesothelial cells can occasionally present with striking intracytoplasmic accumulation of rod- and crystal-like cytoplasmic lamellar inclusions (LIs). Their nature and function are poorly understood, and their diagnostic relevance is unknown. Objective: The aim of this study was to explore the nature of LIs in mesothelial cells and determine their prevalence and diagnostic utility in routine practice. Material and Method: We reviewed a consecutive series of cytological specimens of reactive (n = 102) and malignant effusions (n = 90), respectively. Malignant effusions included malignant mesotheliomas (n = 63) and carcinomas (n = 27). LIs of one effusion were analyzed by electron microscopy (EM). Results: LIs were found exclusively in benign mesothelial cells in 14% (14/102) of reactive and in 4% (1/27) of malignant effusions with carcinomatosis. They were absent in effusions of malignant mesothelioma. EM revealed mainly straight lamellar, less tubular, structures in cisternae of the hyperplasic rough endoplasmic reticulum (rER). Conclusion: Cytoplasmic LIs located within hyperplastic rER can be found in up to 14% of effusions restricted to benign mesothelial cells. They can be used as an indirect morphological clue favoring the diagnosis of benign effusion and helping the cytologist to differentiate between reactive and malignant mesothelial cells in daily practice.
Acta Cytologica

中文翻译：

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良性间皮细胞增生性内质网内的层状包裹体。

简介：在积液细胞学中，间皮细胞偶尔会出现棒状和晶体状细胞质层状内含物（LIs）的明显胞质内积累。他们的性质和功能了解甚少，其诊断意义还不清楚。目的：本研究的目的是探讨间皮细胞中LIs的性质，并确定其在常规实践中的流行程度和诊断用途。材料和方法：我们分别回顾了一系列连续的反应性（ n = 102）和恶性积液（ n = 90）的细胞学标本。恶性积液包括恶性间皮瘤（ n = 63）和癌（ n= 27）。通过电子显微镜（EM）分析一次积液的LI。结果： LIs仅在良性间皮细胞中有14％（14/102）的反应性和4％（1/27）的癌性恶性积液中发现。他们不存在恶性间皮瘤的积液。EM显示增生性粗糙内质网（rER）的水箱中主要是直板层状，较少管状。结论：增生性rER内的细胞质LIs最多见于14％的良性间皮细胞积液中。它们可以用作间接形态学线索，有助于诊断良性积液，并帮助细胞学家在日常实践中区分反应性和恶性间皮细胞。
细胞学学报