Introduction: Uterine tumour resembling ovarian sex cord tumour (UTROSCT) is a very rare tumour of uncertain histogenesis, included in the current classification of endometrial stromal tumours of the World Health Organization. Main symptoms and/or clinical findings: 48-year-old woman with no history of interest, con-sulted for hypermenorrhoea in recent cycles. The gynaecological examination was normal. Main diagnoses, therapeutic interventions, and results: The ultrasound study showed a sub-mucosal nodular lesion of 26 x 21 mm. A diagnostic hysteroscopy was performed, identifying a submucosal myoma not accessible for outpatient removal. Surgical hysteroscopy was perfor-med, proceeding to myomectomy with loop diathermy. Histologically, smooth muscle tissue was observed massively infiltrated by cells with scant cytoplasm and positive glandular differentia-tion for cytokeratins, interpreted as fragments of the myometrial wall infiltrated by carcinoma. An extension study and hysterectomy were performed. No residual neoplasia was identified in the surgical piece. A previous biopsy was re-evaluated and an immunohistochemical study was extended, showing positivity for sexual cord, epithelial, and smooth muscle markers. Given these findings, the definitive diagnosis was UTROSCT. Conclusion: UTROSCT generally shows benign behaviour. However, it is considered to be of uncertain malignant potential, due to its low rate of recurrence and rare metastases. From the histopathological point of view, it is important to recognize this entity, since its histology is varied, mimicking a wide range of tumours, both benign and malignant, making it necessary to perform an immunohistochemical study for its correct diagnosis. & COPY; 2022 Elsevier Espana, S.L.U. All rights reserved.