Squamous cell carcinoma arising within a mature cystic teratoma of the ovary in a postmenopausal woman: A case report and literature review

Malignant transformation of mature cystic teratomas (MCTs) of the ovary is rare, with squamous cell carcinoma (SCC) being the most common histologic subtype. Due to its nonspecific clinical presentation and similarity to benign dermoid cysts, preoperative diagnosis is often challenging, resulting in delayed recognition and poorer outcomes. Risk factors such as postmenopausal status, large tumour size, and elevated tumour markers should serve as red flags prompting clinical suspicion for malignant transformation within an ovarian teratoma. This report describes the case of a 52-year-old woman who presented with chronic abdominal distension, bloating, and early satiety. Imaging revealed large bilateral mature cystic teratomas with associated right-sided hydroureteronephrosis and an elevated CA-125 level. She underwent a total abdominal hysterectomy with bilateral salpingo-oophorectomy, omentectomy, appendectomy and peritoneal washings. Histopathology confirmed a moderately differentiated squamous cell carcinoma arising within a mature cystic teratoma, confined to the right ovary (pT1a). Squamous cell carcinoma arising in a mature cystic teratoma represents a rare but clinically significant form of malignant transformation. This case underscores the importance of considering malignancy in postmenopausal women with large or symptomatic ovarian dermoid cysts and highlights the role of comprehensive histopathological evaluation in establishing an accurate diagnosis and guiding optimal management. • Malignant transformation of ovarian mature cystic teratoma is rare, with squamous cell carcinoma being the predominant histologic subtype. • Advanced age, large tumour size, and elevated tumour markers are key clinical features associated with malignant transformation. • Preoperative differentiation from benign dermoid cysts remains challenging due to overlapping clinical and radiological findings. • Histopathological examination is essential for diagnosis, with immunohistochemistry serving as a supportive adjunct where available. • Early-stage disease confined to the ovary and managed with complete surgical staging is associated with favourable outcomes.