Aigner Thomas, Oliveira André M, Nascimento Antonio G
Department of Pathology, University of Erlangen-Nürnberg, Erlangen, Germany.
Mod Pathol. 2004 Feb;17(2):214-21. doi: 10.1038/modpathol.3800036.
Extraskeletal myxoid chondrosarcoma is a rare mesenchymal soft-tissue malignancy of putative chondrocytic differentiation. Occasional overt cartilage formation, positivity for S-100 protein, and ultrastructural analysis have supported this view. However, most extraskeletal myxoid chondrosarcomas do not show chondroid tissue formation, and S-100 protein is found much less commonly than has been reported. Both these observations cast doubt on the histogenetic classification of extraskeletal myxoid chondrosarcoma as a chondroblastic entity. Mostly using matrix proteins as markers of mesenchymal cell differentiation, we investigated the biochemical matrix composition and cellular phenotype of the tumor cells in representative specimens from 14 extraskeletal myxoid chondrosarcomas. In all but one tumor specimen, which showed histomorphologically overt cartilage formation, only occasional staining for the proteoglycan aggrecan was found. Specimens from two tumors showed presence of collagen type II, and none was positive for collagen type X. Instead, collagen types I, III, and VI were diffusely positive. Also, S-100 protein was largely absent. Our results suggest that the basic cellular phenotype of extraskeletal myxoid chondrosarcoma is not chondrocytic or prechondrocytic and that extraskeletal myxoid chondrosarcoma is not a chondrosarcomatous entity. Extraskeletal myxoid chondrosarcoma consists most likely of primitive mesenchymal cells with focal, multidirectional differentiation. Chondrocytic differentiation is an unusual facet in the spectrum of differentiation patterns exhibited by these lesions.
骨外黏液样软骨肉瘤是一种罕见的间叶性软组织恶性肿瘤，具有假定的软骨细胞分化特征。偶尔出现的明显软骨形成、S-100蛋白阳性以及超微结构分析都支持这一观点。然而，大多数骨外黏液样软骨肉瘤并不显示软骨样组织形成，而且S-100蛋白的发现频率远低于已报道的情况。这两个观察结果都对骨外黏液样软骨肉瘤作为软骨母细胞性实体的组织发生学分类提出了质疑。我们主要使用基质蛋白作为间叶细胞分化的标志物，研究了14例骨外黏液样软骨肉瘤代表性标本中肿瘤细胞的生化基质组成和细胞表型。除了一个组织形态学上显示明显软骨形成的肿瘤标本外，在所有其他标本中仅偶尔发现蛋白聚糖聚集蛋白聚糖染色阳性。两个肿瘤的标本显示存在II型胶原，无一例X型胶原阳性。相反，I型、III型和VI型胶原呈弥漫性阳性。此外，S-100蛋白大多缺失。我们的结果表明，骨外黏液样软骨肉瘤的基本细胞表型不是软骨细胞性或软骨前体细胞性，并且骨外黏液样软骨肉瘤不是软骨肉瘤实体。骨外黏液样软骨肉瘤很可能由具有局灶性、多向分化的原始间叶细胞组成。软骨细胞分化是这些病变所表现出的分化模式谱中的一个不寻常方面。
