UC Davis

•Chronic chemical peritonitis caused by spontaneous rupture of a mature cystic teratoma may result in prolonged hospitalization and respiratory decline and can mimic a gynecologic malignancy.•Earlier surgical intervention for mature teratoma may prevent morbidity.•Inclusion of a gynecologic oncologist is advised for management discussions and/or surgical back-up.•Complex benign gynecologic surgeries may have some benefit for gynecologic oncologic trainees, which can be used for later oncologic cases.