Miettinen M, Monihan J M, Sarlomo-Rikala M, Kovatich A J, Carr N J, Emory T S, Sobin L H
Department of Soft Tissue Pathology, Armed Forces Institute of Pathology, Washington, DC 20306-6000, USA.
Am J Surg Pathol. 1999 Sep;23(9):1109-18. doi: 10.1097/00000478-199909000-00015.
Gastrointestinal stromal tumor or smooth muscle tumor (GIST) is the designation for a major subset of gastrointestinal mesenchymal tumors that histologically, immunohistochemically, and genetically differ from typical leiomyomas, leiomyosarcomas, and schwannomas. Because GISTs, like the interstitial cells of Cajal, the gastrointestinal pacemaker cells, express CD117 (c-kit protein), the origin of GISTs from the interstitial cells of Cajal has been recently proposed. Comparison of GISTs primary in the omentum and mesentery to GISTs primary in the tubular gastrointestinal tract is of particular diagnostic and histogenetic interest in view of the possible similarity of these tumors with the GIST group. In this study, we analyzed 14 omental and 12 mesenteric primary mesenchymal tumors representing smooth muscle tumors or GISTs. These tumors were phenotypically compared with gastric and small intestinal GISTs, leiomyomas of the esophagus, and leiomyosarcomas of the retroperitoneum. Most (13 of 14) omental and mesenteric (10 of 12) tumors showed histologic features similar to GISTs with elongated spindle cells or epithelioid cells with high cellularity; most of these tumors showed low mitotic activity. Omental and mesenteric GISTs were typically positive for CD117 and less consistently for CD34. They often showed alpha-smooth muscle actin reactivity but were virtually negative for desmin and S-100 protein. One omental and two mesenteric tumors showed features of leiomyosarcoma with ovoid, less elongated nuclei, cytoplasmic eosinophilia; all these tumors had significant mitotic activity. These tumors were positive for alpha-smooth muscle actin and two of them for desmin, but all were negative for CD34 and CD117, similar to retroperitoneal leiomyosarcomas. Tumor-related mortality occurred in the group of mesenteric GISTs, but not in the group of omental GISTs. In contrast, all three patients with a true leiomyosarcoma of the omentum or mesentery had documented liver metastases or died of tumor. In summary, we show that tumors phenotypically identical with GISTs occur as primary tumors in the omentum and mesentery. The occurrence of CD117-positive tumors outside the gastrointestinal tract militates against an origin of these tumors exclusively from the interstitial cells of Cajal.
胃肠道间质瘤或平滑肌肿瘤（GIST）是胃肠道间充质肿瘤的一个主要亚群，在组织学、免疫组织化学和遗传学上与典型的平滑肌瘤、平滑肌肉瘤和神经鞘瘤不同。由于GIST，如胃肠道起搏细胞卡哈尔间质细胞，表达CD117（c-kit蛋白），最近有人提出GIST起源于卡哈尔间质细胞。鉴于这些肿瘤与GIST组可能存在相似性，比较大网膜和肠系膜原发性GIST与胃肠道原发性GIST具有特殊的诊断和组织发生学意义。在本研究中，我们分析了14例大网膜和12例肠系膜原发性间充质肿瘤，这些肿瘤代表平滑肌肿瘤或GIST。将这些肿瘤与胃和小肠GIST、食管平滑肌瘤以及腹膜后平滑肌肉瘤进行表型比较。大多数（14例中的13例）大网膜和肠系膜肿瘤（12例中的10例）显示出与GIST相似的组织学特征，具有细长的梭形细胞或高细胞密度的上皮样细胞；这些肿瘤大多显示低有丝分裂活性。大网膜和肠系膜GIST通常CD117呈阳性，CD34阳性率较低。它们常显示α-平滑肌肌动蛋白反应性，但结蛋白和S-100蛋白几乎呈阴性。1例大网膜肿瘤和2例肠系膜肿瘤显示出平滑肌肉瘤的特征，细胞核呈卵圆形，拉长不明显，细胞质嗜酸性；所有这些肿瘤都有明显的有丝分裂活性。这些肿瘤α-平滑肌肌动蛋白呈阳性，其中2例结蛋白呈阳性，但所有肿瘤CD34和CD117均呈阴性，与腹膜后平滑肌肉瘤相似。肠系膜GIST组出现了肿瘤相关死亡，而大网膜GIST组未出现。相反，所有3例大网膜或肠系膜真性平滑肌肉瘤患者均有肝转移记录或死于肿瘤。总之，我们表明，在大网膜和肠系膜中，表型与GIST相同的肿瘤可作为原发性肿瘤出现。胃肠道外CD117阳性肿瘤的出现不利于这些肿瘤仅起源于卡哈尔间质细胞。
