Usual and unusual locations of intrathoracic mesothelial cysts. Is endoscopic resection always possible?

Mesothelial intrathoracic cysts are congenital lesions classically located in the anterior cardiophrenic angle (pleuro-pericardial cysts). Locations elsewhere in the thorax are infrequent. The aim of the study was to describe a 10-year, single-institution experience with endoscopic management of mesothelial cysts by video-assisted thoracoscopy (VT) or video-assisted mediastinoscopy (VM), regardless of their location.

From January 1992 to December 2002, 13 patients (four males and nine females, mean age 49.9 years, range 22-75) underwent surgery for a mesothelial cyst. Information on past history, clinical and radiological presentation, indications for surgery, the surgical procedure and postoperative outcome were collected retrospectively and inserted in a dedicated database. A follow-up visit was performed on December 2002 in all of the patients.

In five patients the cyst was in the right cardio-phrenic angle, in three cases it was in the left cardiophrenic angle. Five cysts were located in the mediastinum (right paratracheal space in two cases, anterior mediastinum in one case, paravertebral mediastinum in two cases). Mean lesion diameter was 7.5 cm (+/-4) x 5 cm (+/-2). Cyst density ranged between 1 and 10 Hounsfield units (HU) in 11 patients. It was respectively 38 and 52 UH in the other two patients. All patients were classed ASA 1 or 2 according to the guidelines of the American Society of Anesthesiologists (ASA). Indications for surgery included the presence of symptoms, uncertain diagnosis, practice of a particular sport or professional activity, and radiological evidence of compression of the superior vena cava (namely for the two paratracheal lesions). Eleven patients were operated on by VT. Two patients with a right paratracheal lesions were operated on by VM. Mean operating time was 60+/-14 min (range 45-80). No postoperative complications were recorded. The mean postoperative stay was 4.3+/-1.2 days (5 days for VT and 2.5 days for VM). Pathology studies confirmed the diagnosis of mesothelial cyst in all cases.

Mesothelial cysts have a heterogeneous distribution within the thorax, and nearly 40% are located elsewhere than in the cardiophrenic angle. Endoscopic resection by VT or VM can be proposed as the treatment of choice even for mesothelial cysts in unusual locations.