Unnoticed Chest Cyst Grew From 4.8 to 13 cm Over Eight Years, Case Report Shows

A cyst in the chest that went unnoticed on a hospital scan grew from 4.8 cm to 13 cm over eight years, filling with blood and eventually forcing surgeons to perform a technically demanding operation that included removing part of the muscular wall of the esophagus. The case, published in the journal General Thoracic and Cardiovascular Surgery Cases, documents in detail how a congenital lesion that most people never learn they have can silently expand, produce symptoms that mimic a malignancy, and become far harder to remove once inflammation has taken hold.

The patient was a man in his 20s with no significant medical history who arrived at a local clinic with a three-day history of epigastric pain and nausea. Upper gastrointestinal endoscopy found nothing abnormal, and he was treated with oral medication. When his symptoms rapidly worsened, chest and abdominal computed tomography performed at another hospital revealed a large mediastinal mass in the visceral compartment measuring 13 cm in diameter. Because the imaging findings suggested malignancy, he was urgently referred and admitted to the reporting department.

On admission, his temperature was 37.9 degrees Celsius, his blood pressure 139/80 mmHg, his heart rate 101 beats per minute, and his oxygen saturation 99 percent on room air. Laboratory tests showed leukocytosis, with a white blood cell count of 10,540 per microliter, and an elevated C-reactive protein level of 10.35 mg/dL, indicating inflammation. Tumor markers were all within normal limits, including carcinoembryonic antigen, cytokeratin fragment, progastrin-releasing peptide, alpha-fetoprotein, human chorionic gonadotropin, anti-acetylcholine receptor antibody, and soluble interleukin-2 receptor.

Contrast-enhanced CT revealed a 13 x 9.3 x 4.5 cm mass in the visceral compartment according to the ITMIG mediastinal compartment classification, extending from below the tracheal bifurcation down to the level of the gastric cardia. The mass showed heterogeneous internal density without significant contrast enhancement and was accompanied by bilateral pleural effusions. Magnetic resonance imaging showed heterogeneous hyperintensity on T1-weighted images and mixed high and low signal intensities on T2-weighted images, a pattern the authors interpreted as suggesting hemorrhage. The tumor margins were well defined, with no evidence of infiltration into surrounding organs. The differential diagnoses included malignant peripheral nerve sheath tumor, solitary fibrous tumor, and a cystic lesion complicated by infection or intracystic bleeding.

The crucial clue came from the archives. Eight years earlier, a CT scan performed at another hospital for the evaluation of abdominal pain had shown a 4.8 cm cystic lesion below the tracheal bifurcation. The lesion was not recognized or reported at the time, so no specific evaluation or follow-up was ever carried out. Comparing the two scans suggested substantial enlargement of the lesion with intracystic hemorrhage. The team considered endoscopic ultrasound-guided fine-needle aspiration biopsy to establish the diagnosis, but abandoned the procedure because the patient’s symptoms had worsened after a previous endoscopic procedure and because of the potential risks of bleeding or mediastinitis.

After admission, the patient’s symptoms improved with antibiotic therapy and fasting, but difficulty with oral intake persisted because the tumor was compressing the esophagus, and follow-up CT showed only minimal shrinkage. Surgical resection was therefore performed on hospital day 12 to establish a definitive diagnosis and relieve symptoms. The operation began thoracoscopically through a three-port approach with the patient in the left lateral decubitus position, using a right thoracic approach based on the tumor’s location and extension. The tumor, covered by mediastinal pleura, was identified between the vertebral body and the lung, with no adhesions to the diaphragm.

Although the tumor was in contact with the inferior vena cava, bronchus, and pericardium, it was successfully dissected from those structures, and no communication with the bronchial tree was identified. The tumor was, however, firmly adherent to the lower esophagus, and partial resection of the esophageal muscularis was required to achieve complete removal. During dissection, dark hemorrhagic fluid leaked from the cyst, confirming intracystic hemorrhage. Rapid cytological examination of the cyst fluid found no findings suggestive of malignancy, and bacterial culture of the cyst contents was negative. The esophageal muscularis defect was repaired with continuous 4-0 PROLENE sutures, endoscopic insufflation confirmed the absence of leakage, and the repair site was reinforced with free pericardial fat. The operation lasted 6 hours and 30 minutes with blood loss of 700 mL, and no transfusions were required.

Histopathological examination revealed a cyst lined with ciliated columnar epithelium, the defining feature of a bronchogenic cyst, together with intracystic hemorrhagic changes and proliferation of granulation tissue around the cyst. Postoperatively, fasting therapy was continued, oral intake began on postoperative day 8, and no leakage or other complications were observed at the esophageal repair site. The patient advanced to a solid diet and was discharged home on postoperative day 20. Six months after surgery he remained asymptomatic, with no imaging evidence of recurrence or residual cyst, and he has returned to work.

Bronchogenic cysts are congenital cystic lesions arising from the primitive foregut and account for approximately 8 percent of all mediastinal tumors, according to the report. Most are asymptomatic and are detected incidentally on imaging, but they may become infected, hemorrhage, or enlarge. In this case, the enlarged cyst compressed the esophagus and gastric cardia, producing gastrointestinal symptoms rather than the chest or back pain and dyspnea more commonly reported. The authors note that in their review of previously reported hemorrhagic bronchogenic cysts, reported sizes ranged from 34 to 90 mm, making their 130 mm lesion larger than those cases, and that previously reported cases presented with hemothorax, whereas in this patient the hemorrhage was confined within the cyst. Intracystic hemorrhage also altered the imaging characteristics, producing heterogeneous internal attenuation and signal intensity that made differentiation from a malignant solid tumor challenging, even though malignancy in bronchogenic cysts is rare, reported in approximately 0.7 percent of adult cases.

The authors draw a broader management lesson from the case. Citing a report that approximately 45 percent of initially asymptomatic patients eventually developed symptoms requiring surgery, and that surgery after symptom onset tended to be technically more challenging even when operative mortality and morbidity were similar, they argue that the potential for substantial enlargement and increasing surgical complexity should be considered when determining the timing of resection. They also acknowledge important limitations: because only two imaging time points were available, the case cannot determine whether the cyst enlarged gradually over the entire eight-year period or whether a substantial part of the enlargement occurred more acutely in association with the intracystic hemorrhage. The team further notes that although bacterial culture of the cyst contents was negative, a superimposed infection could not be completely ruled out because antibiotic therapy before surgery may have reduced the sensitivity of the culture, and the granulation tissue seen histologically may have reflected a secondary inflammatory response to the hemorrhage. As a single-case report, the findings describe one patient’s course rather than a general treatment recommendation, and the authors note that the optimal management of asymptomatic bronchogenic cysts remains controversial.

Subject of Research: A case report of a previously unrecognized bronchogenic cyst that enlarged substantially over eight years and required complex surgical resection.

Article Title: Massive enlargement of a previously unrecognized bronchogenic cyst over 8 years with intracystic hemorrhage and complex surgical resection: a case report

Article References: Kobayashi, S., Fukui, E., Nagata, H., Kimura, K., Kimura, T., Kanou, T., Ose, N., & Shintani, Y. (2026). Massive enlargement of a previously unrecognized bronchogenic cyst over 8 years with intracystic hemorrhage and complex surgical resection: a case report. General Thoracic and Cardiovascular Surgery Cases, 5(1), Article 48. https://doi.org/10.1186/s44215-026-00284-z

Image Credits: AI Generated

DOI: 10.1186/s44215-026-00284-z

Keywords: bronchogenic cyst, mediastinal mass, intracystic hemorrhage, case report, thoracic surgery, computed tomography, magnetic resonance imaging, esophageal muscularis, congenital foregut cyst, surgical resection, incidental finding, inflammatory adhesions