Background: Extragenital Müllerian adenosarcomas are extremely rare tumours characterised by a stromal component of low-grade malignancy and by a benign glandular epithelial component.
Case Report: A 26-year-old woman was admitted to our clinic because of lower abdominal distension and left lower quadrant pain. Clinical and radiological examinations suggested an ovarian malignancy. Laparotomy revealed a cystic mass in the pouch of Douglas, originating from the left sacrouterine ligament. A total excision of the tumour was performed and showed low-grade adenosarcoma without sarcomatous overgrowth. Follow-up at 24 months after the surgery showed no evidence of recurrence.
Conclusion: Mullerian adenosarcoma located in the pouch of Douglas is rare. For treatment, success may be achieved with only excision of the tumour if there is no sarcomatous overgrowth or spread to adjacent tissues.