Revisiting the infracardiac bursa using multimodal methods: topographic anatomy for surgery of the esophagogastric junction

Proposal for T3 classification of esophagogastric junction carcinoma based on the interconnection of extramural anatomical structures

Classification of extramural invasion of esophagogastric junction carcinoma (EGJC) is not yet established. The anatomy surrounding the EGJ alters between the mediastinum and the abdominal cavity. This review proposed a T3 classification of EGJC based on anatomical continuity. Analysis of endoscopic ultrasound images, review of intraoperative images, and detailed observation of surgical specimens were followed by a review of the literature. In the EGJ, the muscularis propria of the esophagus is enclosed in mediastinal adipose tissue called the adventitia, which is surrounded by the diaphragmatic crus and contains the paraesophageal lymph nodes (LNs). After passing through the esophageal hiatus along with the vagus nerves and blood vessels, the adventitia joins the adipose tissue containing the paracardial LNs, which is covered by the peritoneum, and then further divides into the lesser and greater omentum. The connective tissue outside the muscularis propria of the stomach, including the adipose tissue of the omentum, is called the subserosa. According to the TNM classification, T3 esophageal and gastric cancer is defined as invasion of the adventitia and subserosa, respectively. Given that the adventitia is anatomically continuous with the subserosa, T3 tumors of the EGJ can be described as those that extend through the muscularis propria but do not invade the peritoneum or diaphragmatic crus. We propose classifying T3 EGJC as "tumor extends through muscularis propria" rather than using the separate terms "adventitia" and "submucosa". T4 could be "tumor perforates serosa or invades adjacent structures", as per the current gastric cancer classification.

Lung fusion with the liver in chick and quail embryos

Even in mammals with the diaphragm, the lung and liver are likely to attach mutually without separation by any structure in embryos. The aim of this study was to examine whether or not the lung attaches to the liver in embryonic development of birds without diaphragm. First, we ensured the topographical relation between the lung and liver in 12 human embryos at 5 weeks. After the serosal mesothelium was established, the human lung sometimes (3 embryos) attached tightly to the liver without interruption by the developing diaphragm in the pleuroperitoneal fold. Second, we observed the lung-liver interface in chick and quail embryos. At 3-5 days' incubation (stages 20-27), the lung and liver were fused at bilateral narrow areas just above the muscular stomach. Therein, mesenchymal cells, possibly derived from the transverse septum, were intermingled between the lung and liver. The interface tended to be larger in the quail than the chick. At and until 7 days' incubation, the fusion of the lung and liver disappeared and, instead, a membrane connected them bilaterally. The right membrane extended caudally to attach to the mesonephros and caudal vena cava. At 12 days' incubation, bilateral thick folds, containing the abdominal air sac and pleuroperitoneal muscle (striated muscle), separated the dorsally located lung from the liver. Therefore, the lung-liver fusion occurred transiently in birds. Rather than the presence of the muscular diaphragm, whether the lung and liver were fused seemed to depend on a timing and sequence of development of the mesothelial coverings of these viscera.

Whether the infracardiac bursa protect right pleura during laparoscopic radical operation of Siewert type II adenocarcinoma of esophagogastric junction?

BACKGROUND

Transthoracic single-port assisted laparoscopic five-step maneuver inferior mediastinal lymphadenectomy for Siewert type II adenocarcinoma of esophagogastric junction (AEG) has superiority in lower mediastinal lymph nodes dissection and digestive tract reconstruction. However, the right pleura was probably ruptured in this surgical technique. The aim of this study was to explore whether the infracardiac bursa (ICB) exposed could protect right pleura.

METHODS

We retrospectively collected and evaluated the clinical and pathological data of patients who underwent five-step maneuver of transthoracic single-port assisted laparoscopic lower mediastinal lymphadenectomy for Siewert II AEG at Guangdong Provincial Hospital of Chinese Medicine between May 2017 and February 2022.

RESULTS

A total of 49 patients were eligible, including 31 patients in ICB exposed group (group A) and 18 patients in ICB unexposed group (group B). There were no statistically significant differences in baseline characteristics between the two groups. 4 patients (12.9%) had right pleura rupture in group A, while 14 patients (77.8%) in group B, and the difference was statistically significant (p < 0.001). Compared with group B, the extubation time of endotracheal intubation (10.0 (6.0 ~ 12.0) vs. 13.0 (8.0 ~ 15.0) min, p = 0.003) and thoracic drainage tube stay (6.0 (5.0 ~ 7.0) vs. 8.0 (6.0 ~ 10.5) days, p = 0.041) were significantly shorted in the group A. The drainage volume of thorax (351.61 ± 125.00 vs. 418.61 ± 207.86 mL, p = 0.146) was non-significant less and the rate of complications (3.2% vs. 11.1%, p = 0.074) was non-significant lower in group A compared with group B. The postoperative hospital stay (9.0 (8.0,13.0) vs. 9.0 (8.0,12.0) days, p = 0.983) were similar in two groups. No serious adverse event occurred in any patient.

CONCLUSIONS

The ICB exposed could protect the right pleura and may promote postoperative recovery, which may be used as an anatomical marker in inferior mediastinal lymphadenectomy.

Three-dimensional morphogenesis of the omental bursa from four recesses in staged human embryos

The omental bursa (OB) is a complex upper abdominal structure in adults. Its morphological complexity stems from embryonic development. Approximately 200 years ago, the first theory regarding OB development was reported, describing that the OB developed from changes in the position of the stomach and its dorsal mesentery. Thereafter, the second theory reported that the OB originated from three recesses: the right pneumato-enteric recess (rPER), hepato-enteric recess (HER), and pancreatico-enteric recess (PaER). However, the first theory, focusing on the rotation of the stomach, is still described in certain modern embryology textbooks. These two coexisting embryological theories deter the understanding of the anatomical complexity of the OB. This study aimed to unify these two theories into realistic illustrations. Approximately 10 samples per stage among Carnegie stage (CS) 13 and CS21 were microscopically observed and histological serial sections of the representative samples were aligned using the new automatic alignment method. The aligned images were segmented computationally and reconstructed into 3D models. The rPER and the HER encompassed the right half circumference of the esophagus and the stomach at CS13 and CS14, the PaER spread dorsal to the stomach and formed a discoid shape at CS15 and CS16, the infracardiac bursa (ICB) was separated by the diaphragm at CS17 and CS18, and the fourth recess, which we called the greater omental recess (GOR), extended caudally from the PaER among CS19 and CS21. The present results indicate that the fourth recess is also the origin of the OB. These two theories over 200 years can be generally unified into one embryological description indicating a new recess as the origin of the OB.