CASE REPORT article
Front. Med.
Sec. Obstetrics and Gynecology
Triple-negative ovarian apocrine carcinoma arising in a giant mature cystic teratoma: case report and case review
Inês Vaz 1,2
Teodor Svantesson 3
Manfred Kessler 2
Alexander Vogetseder 3
Andreas R. Günthert 1,2
1. gyn-zentrum, Luzern, Switzerland
2. Hirslanden Klinik Sankt Anna, Lucerne, Switzerland
3. Luzerner Kantonsspital Pathologie, Lucerne, Switzerland
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Abstract
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 tumour 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 tumour. 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 behaviour and optimize management of this rare tumour type.
Summary
Keywords
Apocrine carcinoma, case report, Mature cystic teratoma, ovarian cancer, triple-negative
Received
19 November 2025
Accepted
02 February 2026
Copyright
© 2026 Vaz, Svantesson, Kessler, Vogetseder and Günthert. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Inês Vaz
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