A case of chemical peritonitis and pleuritis caused by spontaneous rupture of a benign cystic ovarian teratoma that improved without surgical intervention.

Rupture of a benign cystic ovarian teratoma may result in severe chemical granulomatous peritonitis, a condition mimicking peritonitis carcinomatosa, with patients complaining of common abdominal symptoms. As the precipitating cause of rupture is often indeterminate and the rupture itself is hard to recognize, it is difficult to differentiate from peritonitis of other etiologies, such as gastrointestinal malignancy. We report the case of a 72-year-old female who presented with recurrent pyrexia and abdominal distension. Laboratory data showed signs of inflammation and a high level of carbohydrate antigen 125. Imaging examinations showed left-side-dominant pleural effusion, ascites with peritoneal adhesions, and a left cystic ovarian teratoma. Repeat paracentesis of both the pleural effusion and ascites demonstrated exudative characteristics, but there was no indication of malignancy or signs of infection, including those of tuberculosis. Although exploratory laparotomy was then recommended for conclusive diagnosis and ruling out such gynecological malignancy, the patient declined. Fortunately, laboratory data, radiological images, and other clinical findings gradually improved over the following 12 months. Moreover, a retrospective review of the computed tomography images revealed lipid particles in the ascites, indicative of teratoma rupture. The final diagnosis was chemical peritonitis and pleuritis caused by spontaneous rupture of the benign cystic teratoma. The present case was extremely rare with regard to its diagnosis and clinical progression. Our experience suggests that chemical peritonitis should be included in the differential diagnosis of peritonitis.