Introduction/Background Endometriosis, a benign disease, may transform into malignant tumors in up to 1% of cases. Clear cell carcinoma (CCC) is one of the most common histopathological types of rare malignant tumors in caesarean scar endometriosis, with only about 45 cases that have been reported.

Methodology We present the case of a patient with CCC in caesarean scar endometriosis and a literature review.

Results A 52-year-old Polish woman, postmenopausal for six years, was admitted with a subcutaneous mass developed within the caesarean section scar. Large needle biopsy revealed CCC in endometriosis. In medical history one C-section delivery was followed by two natural labours. There was no record of scar or abdominal endometriosis, or other gynecological diseases. Evaluation of the abdomen revealed a mass, size 33.2x17.5 mm, in the caesarean scar. CT scan confirmed an unilocular mass without other noteworthy findings. At surgery, the tumor was resected with a macroscopic margin of 1 cm, followed by a total laparoscopic hysterectomy with bilateral salpingo-oophorectomy and pelvic lymphadenectomy. Histopathological examination confirmed CCC in endometriosis, resected radically with a negative margin, with no other site of CCC. The tumor board qualified the patient for observation, with no adjuvant chemotherapy recommended. During follow-up, six and eleven months post-surgery, no pathologies were observed.

The review of the literature confirmed that 92% of women had a caesarean section, but most of the cases presented a history of endometriosis. Up to 64% of reported cases were discovered in an advanced stage, required chemotherapy and radiotherapy apart from surgical treatment, and had poor prognosis.

Conclusion CCC in endometriosis arising in caesarean section scar is an invasive and rare disease with a poor prognosis; most of the cases are diagnosed at an advanced stage of malignancy.

According to our case, early investigation and invasive surgical treatment without chemotherapy may be effective.

Disclosures No conflict of interests.