This case report details the successful surgical treatment of a case of gastric GIST near the cardia using a modified CLEAN-NET. Additionally, we present a video demonstration showcasing the technique, which does not employ the circular incision of conventional CLEAN-NET. Instead, it utilizes a semicircular seromuscular layer incision exclusively on the side opposite the cardia, necessitating preservation.

Previous studies have outlined techniques for combined laparoscopic and intraoperative endoscopy surgery. The laparoscopic and endoscopic cooperative surgery (LECS) procedure, developed by Hiki et al. in 2008, integrates endoscopic mucosal dissection and laparoscopic gastric wall resection to delineate the exact cutting line [3]. The combination of laparoscopic and endoscopic approaches to neoplasia with a non-exposure technique (CLEAN-NET) is an LECS-related procedure developed by Inoue et al. in 2012. Thus, nonexposed, full-thickness resection is performed after a seromuscular incision that preserves the continuity of the mucosa that works as a barrier [2]. The CLEAN-NET is generally indicated for tumors up to 3 cm in diameter and calls for the incision of the seromuscular layer in a circular shape around the base of the tumor [1, 2, 4, 5]. Additionally, intragastric surgery has been reported as a procedure for partial gastrectomy that does not require lymph node dissection [6,7,8].

The CLEAN-NET surgical procedure is straightforward when the tumor can be extruded from the lumen through the seromuscular layer incision site and full-thickness resection can be entirely performed using a linear stapler [5]. However, if the tumor is close to the cardia, which requires reliable preservation of the cardia, full-thickness resection using a linear stapler is challenging. In such cases, the gastric wall, including the tumor, is removed at the mucosal level using a linear stapler, and the seromuscular layer defect is manually sewn laparoscopically [9]. This requires a more complicated surgical technique and is more difficult to perform than full-thickness resection using a linear stapler.

The seromuscular layer incision proposed in this case report for the modified CLEAN-NET differs from the circular incision around the base of the tumor, as in conventional CLEAN-NET. Instead, it is a semicircular incision made near the base of the tumor, specifically on the opposite side of the cardia. Using two laparoscopic forceps, the tumor was easily pushed out through the seromuscular layer incision with optimal and minimal length relative to the tumor size. When clamping the gastric wall, including the tumor, full-thickness resection is easily performed with only the linear stapler if attention is paid to full-thickness clamping of the gastric wall on the side opposite to the cardia, because the gastric wall on the side of the cardia is preserved in full-thickness. Because the optimal and minimal seromuscular layer incision suppressed excessive extension of the gastric wall during clamping, tumor resection was easily achieved using a single 60 mm linear stapler. Because the seromuscular layer incision is shorter than that of conventional CLEAN-NET, the likelihood of mucosal damage is reduced; this is expected to improve the feasibility of non-exposed surgery. Intraoperative endoscopy to confirm cardia preservation and residual tumor absence also improved the accuracy of this method. One advantage of LECS is the use of endoscopic air inflation to expand the stomach after tumor resection, confirming the absence of pseudodiverticula with seromuscular layer defect on the staple line. In cases with lesions close to the cardia, the surgical field opposite to the cardia is suitable for lesions on the anterior wall; even in cases with lesions on the posterior wall, as in the present case, the surgical field of view opposite to the cardia is favorable because the stomach is inverted cranially. Therefore, a semicircular seromuscular layer incision in this surgical procedure can be performed with a good surgical field view for both anterior and posterior wall lesions. To the best of our knowledge, this is the first report of a modified CLEAN-NET with a semicircular incision in the seromuscular layer.

The surgical procedure described in this case report has several limitations. While the application of CLEAN-NET to early gastric cancer surgery has recently been reported [10, 11], only tumors of certain sizes may be extracted out of the lumen through the minimal semicircular seromuscular layer incision. Thus, it is not a suitable surgical procedure for substantial or small GIST or flat tumors, such as early gastric cancer, as pushing the tumor extraluminally is difficult. Although this surgical procedure has some advantages, its indications are limited to submucosal tumors, such as GIST, that are 2–3 cm in size. This limitation is relatively minor as transitioning to conventional CLEAN-NET is straightforward; it involves simply changing the seromuscular layer incision from semicircular to circumferential.

In conclusion, although surgical procedures for treating gastric GIST near the cardia demand meticulous attention to tumor size, which can present challenges, the modified CLEAN-NET with a semicircular seromuscular layer incision emerges as a potentially valuable option for surgical procedures. It leverages the benefits of conventional CLEAN-NET while streamlining the surgical technique, offering a promising approach for these complex cases.