Should spring water cysts of the mediastinum require excisional resection? A case report.

Introduction And Importance: Mediastinal cysts account for 20-32% of all mediastinal lesions. Complete surgical excision is the standard therapy for mediastinal cysts. Translucent cysts containing crystal-clear fluid are called "spring water cysts." We experienced a case of mediastinal spring water cyst fenestrated under video-assisted thoracoscopy with a miniaturized endoscope (mini-VATS) as an alternative to excisional resection.

Case Presentation: A 49-year-old woman presented with back pain. Chest CT revealed a posterior mediastinal mass measuring 4.2 × 1.8 × 3.2 cm closed to the tenth thoracic vertebra. Chest MRI demonstrated hypo-intensity on T1-weighted images and hyper-intensity on T2-weighted images. It was estimated that the posterior mediastinal mass did not contain a tumor component. The tumor was growing and symptomatic; therefore, we performed surgical cyst fenestration without excision of the cyst under mini-VATS. The patient experienced complete relief of symptoms. Fluid accumulation in the cyst was not observed on CT images 12 months postoperatively.

Clinical Discussion: Kozu et al. reported that all 108 primary mediastinal cysts were resected completely and were recurrence-free after a mean follow-up of 41 ± 26 months. In the case of a functional hydrocele such as spring water cyst, we believe that even if fluid is produced, the thoracic pleura is capable of absorbing the fluid, and the cyst wall might not recur even if the wall is left in place. Fluid drainage through fenestration may prevent recurrent fluid collection.

Conclusion: Fenestration of non-neoplastic mediastinal cysts under mini-VATS might be a less invasive radical procedure compared to complete resection.