Acquired intrathoracic kidney

A 63 year old female with neurofibromatosis was referred to the Pulmonary Clinic of the University Hospital for evaluation of a right thoracic mass. Physical examination revealed subcutaneous nodules over the trunk area, café au lait spots, and dullness to percussion with decreased breath sounds at the right lung base. The chest X ray showed a 4 cm mass at the right lung base. Computerized tomography of the chest demonstrated a right posterior diaphragmatic hernia with displacement of the liver and kidney into the thoracic cavity. Renal scan confirmed the location of the kidney in the right hemithorax showing normal renal cortical function. Intrathoracic kidney is a very rare finding, most are found in males and are asymptomatic. They are usually found in the left hemithorax and associated to a normal diaphragm. Only 0.25% are associated with a diaphragmatic hernia. In our patient, there was a history of mild trauma five years earlier, but this did not clearly explain how the kidney became ectopic. Acquired intrathoracic kidney should be considered in the differential diagnosis of a lung mass to avoid an unnecessary thoracotomy and nephrectomy.