We encountered a patient with GTF after esophageal surgery through the retrosternal route, who could be successfully treated with conservative therapy. Here, we identified two important clinical issues: diagnosis of GTF after esophageal surgery through the retrosternal route and successful treatment with only conservative therapy.

GTF after esophageal surgery through the retrosternal route is extremely rare. Most previous reports of GTF describe the occurrence of the fistula through the posterior mediastinal route. Some previous reports described that GTF occurred only in posterior mediastinal route reconstruction [1]. However, in our patient, GTF occurred during retrosternal route reconstruction. So far, only one case of GTF after esophageal surgery through the retrosternal route has been reported [2]. In the case, surgical treatment of GTF was finally needed. Our patient was the first case that conservative treatment was successful for GTF after esophageal surgery through retrosternal route (Table 1).

One reason of GTF after esophageal surgery through the retrosternal route is that the treatment for anastomotic leakage was prolonged. The fragile membranous portion of the trachea was perforated because of continuous exposure to the abscess. One case report described a patient diagnosed with pharyngeal abscess, subsequent descending necrotizing mediastinitis, and tracheal ulceration in the membranous portion that eventually perforated [3].

In the case of abscess formation from anastomotic leakage, the options of open drainage, percutaneous drainage, or endoscopic drainage [4] could have been considered. However, open drainage was not performed because the leakage site was on the posterior side of the anastomosis, with contrast pooling in the mediastinum, making drainage more difficult compared to a ventral anastomotic leak. Additionally, the mediastinum tends to become localized due to surrounding tissues, and the patient's general condition was stable at the time.

Similarly, percutaneous drainage was not performed due to the anatomical difficulty of reaching the posterior side of the anastomosis, as it was surrounded by the sternum and the aortic arch, as shown in Fig. 3. Endoscopic drainage was also avoided because it was only 10 days after surgery, and there was concern about stressing the anastomosis. The cavity gradually reduced over time with nasogastric decompression, and the patient’s condition remained stable, so drainage was not pursued.

For these reasons, we chose conservative management with nasogastric decompression alone. Conservative treatment has also been reported for mediastinal abscesses in cases with stable vitals, minimal signs of infection, and spontaneous, effective drainage [5]. However, we acknowledge that earlier drainage could have potentially prevented the GTF.

Another reason could be difficulty in the flow of digestive juices into the gastric tube due to anastomotic stenosis, causing abscess worsening. We believe that balloon dilatation significantly contributed to the treatment outcome.

Few case reports have discussed conservative, endoscopic, and surgical treatment for GTF, with a lack of standard management for GTF. Endoscopic treatment for GTF consists of stent insertion into the gastric tube and/or tracheobronchial tree, clip application, and fibrin glue injection [6, 7]. Surgical treatment of GTF includes resection of the perforated gastric conduit, closure of the bronchial fistula using a pectoralis muscle flap, latissimus dorsi myocutaneous flap or thymus pedicle flap, and reconstruction of the esophagostomy [2, 8,9,10].

Although surgical treatment shows high recovery rates, it is highly invasive [6]. In contrast, conservative and endoscopic treatments are less invasive and can improve the condition of GTF patients who are otherwise in stable condition.

One previous report summarized 70 cases of GTF, which were subdivided into five types: necrosis type, leakage type, ulcer type, compression type, and other types [6]. The site of the fistula determined the GTF type. In the leakage type, the site of the fistula was located at the same level as the anastomotic site, and when present in the higher trachea, the outcomes were better with conservative therapy.

Another report described the clinical characteristics and outcomes of 10 cases of GTF [11]. The leakage type in the higher trachea appeared between postoperative days 8–35 and had better outcomes with conservative therapy. Our patient had the leakage type of GTF, which met the above conditions for conservative therapy.

One case report described the following conditions for conservative treatment as the optimal management course: (1) absence of critical cough upon swallowing, fever, and recurrent pneumonia; (2) no hematological evidence of acute inflammatory reaction; (3) no evidence of gastric tube necrosis; (4) anastomotic leakage type of GTF appearing approximately two weeks after esophagectomy; and (5) the GTF located in higher trachea [12]. Our case met the above criteria, qualifying for conservative management, which was successful.

If the situation permits, conservative therapy may be the optimal management option because of its simplicity and minimal invasiveness.

Additionally, other minimally invasive methods, such as fistula closure using fibrin glue, PGA sheets [13], or histoacryl [14] have also been reported. In cases where the fistula does not change over time, unlike in this case where repeated balloon dilations gradually reduced the fistula, these methods could be considered.

However, surgical intervention is necessary in case of severe symptoms or failure of conservative treatment.

Most previous reports described that GTF was unique to mediastinal route reconstruction, which involved direct communication between the anastomosis site and adjacent trachea or main bronchus. However, as in this case, we found that GTF could also occur during retrosternal route reconstruction. There are two possible ways for GTF to occur in retrosternal route reconstruction. It can occur because the retrosternal route also includes a part of the neck where the gastric tube and trachea meet or because GTF can be formed through a mediastinal abscess consisting of suture failure at the anastomotic site. In this case, the reason was the latter.