Objectives INTRODUCTION: Mesonephric-like Mullerian adenocarcinomas of the ovaries are extremely rare gynecological malignancies. Their embryological and histological origin remains debatable. The more prevalent tumorigenic theories support either development from Mesonephric duct remnants of the female genital tract, or development from Mullerian lesions that undergo Mesonephric differentiation.

Methods Case-report of a patient with ovarian Mesonephric-like Mullerian adenocarcinoma.

Results CASE REPORT: 64 years old female patient with medical history of hypothyroidism and dyslipidemia. During annual gynecological US-screening examination, a solid formation (4cm diameter) was found on the left ovary. An ensuing MRI tomography diagnosed a solid ovarian mass. Further staging with CTs and PET-CT scan excluded distant neoplasmatic dissemination. Subsequently, surgical total hysterectomy was performed. After histological evaluation, the analysis concluded to low-grade Mesonephric-like Mullerian adenocarcinoma of left ovary, adjacent to multiple foci of endometriosis. Due to tumor rarity, the histological results were re-checked and verified by multiple histology experts. The patient received adjuvant chemotherapy with 6 circles of Carboplatin/paclitaxel. Treatment was completed without significant side-effects, except for mild nausea and hand-foot syndrome. Follow-up examinations showed complete disease-remission. Currently, the patient is regularly monitored with scheduled-periodic assessments, without any sign of recurrence. Moreover molecular analysis revealed heterozygous somatic KRAS mutation NM_033360.4:c.35G>A:p.(Gly12Asp), and heterozygous genomic PMS2 mutation NM_000535.7:c.2559C>G p.(Ile853Met)

Conclusions CONCLUSION: Mesonephric-like Mullerian adenocarcinomas of ovaries are extremely rare tumors (<15 literature reports in Pubmed, Scopus). The most prevalent theory of tumorigenesis, involves cancer development from Mullerian lesions (eg foci of endometriosis) that undergo Mesonephric differentiation. Further research is necessary to illuminate the neoplastic nature of these lesions.