Introduction/Background Vaginal adenosis occurs when normal squamous cell mucosa is replaced with metaplastic glandular epithelium. One known risk factor for vaginal adenosis is in-utero diethylstilbestrol (DES) exposure. DES is a synthetic oestrogen prescribed in the past to prevent miscarriages and preterm labour. Adenosis may present with a variety of symptoms including pain, vaginal bleeding and discharge.

Case report A 46-year-old female presented with symptoms of vaginal pain and discharge. Pap test result showed atypical glandular cells. HPV testing was negative. History of intrauterine exposure to DES was negative. Speculum examination revealed oedematous vaginal walls covered with discharge. She had dilatation and curettage (DEC), and her histopathological results showed atypical lobular endocervical glandular hyperplasia. Subsequently, she underwent cervical conisation, and her results were consistent with invasive cervical adenocarcinoma with negative margins. MRI demonstrated no residual neoplastic tissue with cystic changes on the proximal and middle third of the vagina. She was referred for radical hysterectomy. The results showed no signs of residual neoplastic tissue, however vaginal surgical margins passed through vaginal adenosis. She was referred to oncology for radiotherapy. After one year, the patient presented again with vaginal pain and her speculum examination revealed bleeding lesions at the vaginal entrance. These lesions were biopsied and the result was consistent with adenocarcinoma (malignant transformation of the vaginal adenosis). The immunotherapy test for programmed death ligand 1 (PD-L1) was positive. The patient is currently under chemotherapy and immunotherapy.

Conclusion In this very rare case, malignant transformation of endocervical glands and vaginal adenosis happened in a close period. Malignant transformation of vaginal adenosis cannot be controlled or predicted. In women without known DES exposure, the correlation between vaginal adenosis and a primary vaginal malignancy is even more unclear. Treatment is controversial, with a combination of surgical treatment, radiotherapy, chemotherapy and immunotherapy.

Disclosures No conflicts of interest are reported.