Mesothelial cyst derived from chest wall pleura growing after thoracic surgery: a case report

BACKGROUND: Intrathoracic mesothelial cysts almost always arise in the mediastinum, and extramediastinal mesothelial cysts are extremely rare. Here we describe a case of mesothelial cyst derived from the chest wall pleura growing after thoracic surgery. CASE PRESENTATION: A 63-year-old Japanese woman was referred to our department. She had undergone total hysterectomy for cervical carcinoma and two lung wedge resections for metastatic lung cancer on the upper and lower lobes of her right lung and lower lobe of her left lung. After the thoracic surgery, an intrathoracic chest wall mass was found, which grew gradually. Computed tomography demonstrated a 2.0 × 1.8 cm low-density mass without contrast effect. Magnetic resonance imaging demonstrated a low-intensity mass in T1-weighted imaging and a high-intensity mass in T2-weighted imaging. Thoracoscopic excision of the mass was performed. The cystic mass was thought to be derived from her chest wall and was pathologically diagnosed as mesothelial cyst. Five years after the surgery, she has no evidence of recurrence of the cyst or cervical carcinoma. CONCLUSIONS: The genesis of extramediastinal mesothelial cysts may be related to inflammation. From this perspective, extramediastinal mesothelial cysts may have different characteristics from pericardial cysts and resemble peritoneal inclusion cysts. Although, extramediastinal mesothelial cysts are not established, their characteristics resemble peritoneal inclusion cysts; therefore, such interesting intrathoracic cysts should be carefully resected considering the risk.