Malignant transformation of uterine serosal endometriosis to clear cell carcinoma in a postmenopausal patient: a rare case report.

BACKGROUND

Endometriosis is a prevalent benign condition among women of reproductive age. While the overall rate of endometriosis-associated malignancy is low, the risk of malignant transformation increases significantly in postmenopausal patients, with malignancy primarily occurring in ovarian lesions. Reports of malignancy in postmenopausal endometriosis affecting the serosal surface of the uterus are extremely rare. The clinical features are poorly understood, standardised diagnostic or treatment guidelines are lacking, and the mechanisms underlying this malignancy are unknown.

CASE PRESENTATION: The following case report details a 62-year-old postmenopausal woman who presented with dull lower abdominal pain. A colour Doppler ultrasound revealed a pelvic mass, and a preoperative CT scan suggested a possible tumour of left ovarian origin; tumour marker tests were negative. Laparoscopic exploration confirmed that the lesion originated from the serosal surface of the posterior uterine wall. Furthermore, no abnormalities were noted in the bilateral adnexa. The surgical intervention undertaken was a total hysterectomy, accompanied by bilateral adnexal resection, pelvic lymphadenectomy, pelvic peritoneal biopsy, and omental biopsy. Postoperative pathology confirmed the presence of endometriosis of the uterine serosa, accompanied by focal clear cell transformation. The patient did not receive adjuvant chemotherapy and was placed under close follow-up; a follow-up examination six months later revealed no abnormalities.

CONCLUSIONS

The transformation of uterine serosal surface endometriosis into clear cell carcinoma is an exceptionally rare occurrence. This case demonstrates the coexistence of benign endometriosis, atypical endometriosis and clear cell carcinoma components within a single histological section, providing crucial morphological evidence for investigating the pathological progression of malignant transformations in extra-ovarian endometriosis.