Department of Gastroenterology, National Cancer Center Hospital East, Kashiwa City, Chiba, Japan.
BMC Gastroenterol. 2013 Aug 19;13:129. doi: 10.1186/1471-230X-13-129.
Laterally spreading tumors (LSTs) are generally defined as superficial lesions ≥10 mm in diameter that typically extend laterally rather than vertically along the colonic wall. LSTs are usually categorized into 2 subtypes: granular type and nongranular type. Large nodules or depressed areas in granular-type LSTs (LST-Gs) are endoscopic findings of a cancerous component and sometimes represent submucosal invasion. However, the lateral growth and development of LST-Gs remains unclear.
This case report describes a case of 79-year-old woman who underwent total colonoscopy due to a positive fecal occult blood test and was detected a LST-G, about 30 mm in diameter in the lower rectum. The lesion consisted of not only aggregated small and large nodules typically seen in LST-Gs but also the hardly elevated flat parts. In the flat part, there were dilated round pits and no evident capillary vessels. Three months later, the flat part increased in height, the dilated round pits were partly replaced by type IIIL pits, and capillary vessels were evident. The lesion was removed by endoscopic submucosal dissection, and diagnosed pathologically as tubular adenoma. We performed the sequence analyses on KRAS, BRAF, NRAS and PIK3CA genes in flat part and nodular part separately, and a mutation of KRAS gene at codon 146 was observed at only nodular part, suggesting probable that nodular part be a precancerous lesion.
This is a unique and suggestive case, providing information on progression of LST-Gs at the very early stage to carcinogenesis.
侧向伸展性肿瘤（LST）通常被定义为直径≥10mm 的表浅病变，其特征为沿结肠壁侧向而非垂直方向延伸。LST 通常分为 2 个亚型：颗粒型和非颗粒型。颗粒型 LST（LST-G）中的大结节或凹陷区域是癌性成分的内镜表现，有时代表黏膜下浸润。然而，LST-G 的侧向生长和发展尚不清楚。
本病例报告描述了一名 79 岁女性的病例，因粪便潜血试验阳性而行全结肠镜检查，于直肠下段发现一个直径约 30mm 的 LST-G。该病变不仅包含 LST-G 中常见的聚集性大小不等的结节，还有难以抬高的平坦部分。在平坦部分，有扩张的圆形凹陷，没有明显的毛细血管。3 个月后，平坦部分高度增加，扩张的圆形凹陷部分被 IIIL 型凹陷取代，毛细血管明显。病变通过内镜黏膜下剥离术切除，病理诊断为管状腺瘤。我们分别对平坦部分和结节部分的 KRAS、BRAF、NRAS 和 PIK3CA 基因进行了测序分析，仅在结节部分观察到 KRAS 基因 146 密码子的突变，提示结节部分可能是癌前病变。
这是一个独特且提示性的病例，提供了 LST-G 向癌变早期进展的信息。
