Rupture of a huge infectious abdominal chronic expanding hematoma

A 72-year-old woman was referred to our hospital with the diagnosis of peritonitis due to the rupture of a huge abdominal cystic tumor, 27 cm in diameter. Abdominal computed tomography 14 years before revealed the tumor, which was 18 cm in diameter. She had undergone no examinations or treatment in the interim. She was in shock upon presentation to our hospital. She was intubated immediately and underwent an emergent laparotomy. The huge ruptured tumor with adherent small intestine was resected. The tumor weighed 6 kg and consisted of solid and cystic components filled with 4 kg of brown feces-like fluid. Bacteroides fragilis was detected in a fluid specimen. The cystic component of the tumor was filled with old blood clots, and a portion of the tumor wall was highly calcified. Old blood and fibrin with blood vessels of various sizes inside the tumor were observed during the pathologic evaluation; there were no malignant features. The final pathologic diagnosis was a chronic expanding hematoma (CEH). The patient had an uneventful recovery and was discharged 16 days post-operatively. She was involved in a traffic accident approximately 30 years before the current hospital admission; however, she did not recall if she had abdominal pain at that time. A CEH is a benign lesion, but rupture of a CEH can be life-threatening.