Intrathoracic splenosis secondary to previous penetrating thoracoabdominal trauma diagnosed during delayed diaphragmatic hernia repair.

Although intraperitoneal splenosis is a very common disease, intrathoracic splenosis is very rare. It is generally an asymptomatic disease that occurs after thoracoabdominal trauma, and is diagnosed as an intrathoracic mass that leads to unnecessary investigations to be differentiated from other benign or malignant lesions of the chest. We present a patient with an intrathoracic mass which was preoperatively diagnosed as a diaphragmatic hernia on chest X-ray and magnetic resonance imaging. We have intraoperatively recognized that many pieces of splenic tissue have been herniated through a diaphragmatic defect, and formed intrathoracic splenosis. We repaired the diaphragmatic hernia defect after excision of fragments of the spleen.