Abstract
A 63-year-old man experienced abdominal pain with vomiting upon waking, and was diagnosed with acute gastroenteritis in emergency outpatient care. Symptoms persisted through outpatient follow-up, and he returned 4 days later. Blood testing showed elevated inflammatory reactions, and abdominal CT showed enlargement of the appendix accompanied by an abscess, so emergency surgery was performed under a presumptive diagnosis of acute appendicitis. On postoperative examination, CT showed thickening of the small intestinal wall and a cystic lesion. Intraoperative findings included a cystic lesion 7cm in diameter in the small intestine, which had ruptured and formed an abscess in the periphery. We therefore excised about 20 cm of the small intestine, including the cyst, and performed secondary resection of the appendix, which had exhibited signs of inflammation. Histopathological findings suggested that the cyst was derived from the mesothelium, and mesothelial cyst was diagnosed. Mesothelial cyst derived from the small intestine is extremely rare, and we report our experience with this case in which spontaneous rupture resulted in acute abdomen.
