We report a rare co-occurrence of an adenoma malignum and an adenocarcinoma in a 30-year-old woman with Peutz-Jeghers syndrome. The woman was diagnosed with Peutz-Jeghers syndrome based on an endoscopic biopsy after vaginal bleeding. A pelvic examination and an MRI revealed the co-occurrence of a 4×5 cm protruding adenocarcinoma of FIGO stage Ib2 based on a punch biopsy and a 4.5×5.7 cm multilocular cystic mass above the solid cancer. The patient received two courses of neoadjuvant chemotherapy, followed by a laparoscopic radical hysterectomy with pelvic lymph node dissection. Pathologic findings were consistent with adenocarcinoma (40%) and adenoma malignum (60%) confined to the cervix. Three courses of adjuvant chemotherapy were performed and no clinical evidence of recurrence was seen during a 12 month follow-up period. This study will contribute to defining the best diagnosis and treatment for these rare complicating tumors.