Jeffrey P B, Biava C G, Davis R L
Department of Anatomic Pathology University of California, San Francisco Long-Moffit Hospitals.
Am J Clin Pathol. 1995 Mar;103(3):271-9. doi: 10.1093/ajcp/103.3.271.
"Chondroid chordoma" is a controversial and confusing entity that was originally described by Heffelfinger and colleagues as a biphasic malignant neoplasm possessing elements of both chordoma and cartilaginous tissue. Because the premise for this distinction was based strictly on histomorphologic criteria, the light microscopic, immunohistochemical, and electron microscopic features of the chondroid and chordoid areas of five chondroid chordomas of the skull base were evaluated separately, and compared to five typical chordomas and six low grade chondrosarcomas. Using light microscopy, chondroid chordoma revealed areas that resembled typical chordoma (chordoid areas) and areas that resembled low grade chondrosarcoma (chondroid areas). However, both the chordoid and chondroid areas had an epithelial phenotype and stained strongly for cytokeratin and EMA as well as S-100. 5'-nucleotidase, an enzyme that has been described in chordoma but not in chondrosarcoma, was found in both the chordoid and chondroid areas of one chondroid chordoma. Electron microscopic studies of both the chordoid and chondroid areas in four of the tumors demonstrated both tonofibrils and desmosomes. Chordoma demonstrated immunohistochemical and electron microscopic features that were nearly identical to chondroid chordoma. Chordoma was cytokeratin, EMA, S-100, and 5'-nucleotidase positive. Ultrastructurally, chordoma exhibited variably-sized vacuoles, abundant rough endoplasmic reticulum (RER), and desmosomes with tonofilaments. In contrast to chondroid chordoma, chondrosarcoma consistently stained for only S-100 protein and was cytokeratin, EMA and 5'-nucleotidase negative. Ultrastructurally, chondrosarcoma demonstrated a flocculogranular matrix, glycogen, abundant RER, and scalloped cellular outlines, but lacked desmosomes with tonofilaments. These findings indicate that "chondroid chordoma" is a variant of chordoma with histologic features that may mimic chondrosarcoma. Despite the resemblance of these hyalinized areas to cartilaginous tissue, these tumors retain their epithelial phenotype. Biphasic differentiation is not present. These findings undermine the original premise for distinguishing "chondroid chordoma" from typical chordoma. The authors propose that these tumors be classified as "hyalinized chordomas," rather than "chondroid chordoma," to clarify their histogenesis and avoid confusion with chondrosarcomas of the base of the skull.
“软骨样脊索瘤”是一种存在争议且容易混淆的病变，最初由赫费尔芬格及其同事描述为一种具有脊索瘤和软骨组织成分的双相恶性肿瘤。由于这种区分的前提严格基于组织形态学标准，因此分别评估了5例颅底软骨样脊索瘤的软骨样和脊索样区域的光镜、免疫组化及电镜特征，并与5例典型脊索瘤和6例低级别软骨肉瘤进行比较。光镜下，软骨样脊索瘤可见类似典型脊索瘤的区域（脊索样区域）和类似低级别软骨肉瘤的区域（软骨样区域）。然而，脊索样和软骨样区域均具有上皮表型，细胞角蛋白、上皮膜抗原（EMA）及S-100均呈强阳性。在1例软骨样脊索瘤的脊索样和软骨样区域均发现了5'-核苷酸酶，该酶在脊索瘤中有描述，但在软骨肉瘤中未发现。对4例肿瘤的脊索样和软骨样区域进行电镜研究，均显示有张力原纤维和桥粒。脊索瘤的免疫组化和电镜特征与软骨样脊索瘤几乎相同。脊索瘤细胞角蛋白、EMA、S-100及5'-核苷酸酶均为阳性。超微结构上，脊索瘤表现为大小不一的空泡、丰富的粗面内质网（RER）以及带有张力丝的桥粒。与软骨样脊索瘤不同，软骨肉瘤仅S-100蛋白持续呈阳性，细胞角蛋白、EMA及5'-核苷酸酶均为阴性。超微结构上，软骨肉瘤显示有絮状颗粒基质、糖原、丰富的RER及呈扇贝状的细胞轮廓，但缺乏带有张力丝的桥粒。这些发现表明，“软骨样脊索瘤”是脊索瘤的一种变异型，其组织学特征可能类似软骨肉瘤。尽管这些玻璃样变区域类似软骨组织，但这些肿瘤仍保留其上皮表型。不存在双相分化。这些发现削弱了将“软骨样脊索瘤”与典型脊索瘤区分开来的最初前提。作者建议将这些肿瘤归类为“玻璃样变脊索瘤”，而非“软骨样脊索瘤”，以阐明其组织发生并避免与颅底软骨肉瘤混淆。
