Abstract
Empyema necessitans is a rare complication of untreated pleural space infections. Untreated empyema that spontaneously burrows through the parietal pleura can present with a subcutaneous abscess. In the following case report, we present a 55 year old male who presented with an intermittent left chest mass later to be diagnosed as empyema necessitans. The patient suffered from a hemothorax treated by tube thoracostomy three years prior. The patient had been seen several times and no mass could be appreciated. The patient was diagnosed with empyema necessitans on computed tomography and treated with a left thoracotomy. Empyema necessitans can develop if pleural infections are left untreated. We present an unusual presentation of this rare complication. Empyema necessitans should be kept in the differential diagnosis of patients with left chest masses or abscesses.