Triple-negative ovarian apocrine carcinoma arising in a giant mature cystic teratoma: Case Report and Case Review
Background
Mature cystic teratoma (MCT) of the ovary is one of the most common benign ovarian neoplasms in women of reproductive age. Malignant transformation is rare, occurring in approximately 1–2% of cases, and transformation into apocrine carcinoma is exceptionally uncommon. To date, only four such cases have been reported.
Case presentation
We describe a 68-year-old woman with a giant ovarian tumor that had been slowly growing for over 40 years. Imaging revealed a 35 cm cystic mass, consistent with malignant degeneration and serum CA-125 was elevated (559 U/mL). The patient underwent exploratory laparotomy with complete removal of a 11 kg right ovarian tumor. Histopathological examination revealed a mature cystic teratoma of the ovary with malignant transformation into high-grade apocrine carcinoma. The tumor involved the cyst wall multifocally and showed no capsular rupture. Immunohistochemistry showed AR and EGFR positivity, ER and PR negativity, and HER2 score 2+ (FISH negative). The PET-CT showed 2 pericaval lymph nodes possible reactive after surgery. The postoperative course was uneventful, and from the outset the patient refused a comprehensive staging with hysterectomy, omentectomy and lymphadenectomy. At 6-month follow-up, CA-125 remained normal (<8 U/mL), with no evidence of recurrence.
Conclusion
Ovarian apocrine carcinoma arising in MCT is exceedingly rare. Complete surgical excision remains the cornerstone of treatment, as no standard systemic therapy has been established. Further accumulation of similar cases is essential to better understand the biological behavior and optimize management of this rare tumor type.