Collision tumour of the ovary, malignant Brenner tumour and mature cystic teratoma
Jennifer Johnson, Mid-Yorkshire Teaching NHS Trust
Background
A 69-year-old woman was referred for an urgent ultrasound scan of her pelvis by her General Practitioner (GP), due to a history of left lower abdominal pain for a few months. On examination, the GP thought that there was a palpable mass in the LIF. There was no previous imaging of the pelvis available for comparison and the patient was otherwise fit and well.
Case Summary
Ultrasound examination revealed two large cystic lesions arising from the pelvis measuring 19.5cm and 10.5cm diameter respectively. The smaller lesion contained an internal echogenic component with ultrasound appearances typical for a dermoid cyst. The larger lesion contained both cystic and solid components with internal vascularity noted within the solid area. The left ovary appeared normal and separate to these lesions and the right ovary was not seen. A small amount of pelvic free fluid was noted. An upper abdominal survey was unremarkable. The findings were reported as a large cystic lesion with some suspicious features and a possible co-existing dermoid cyst. CT scan confirmed the ultrasound findings with the larger lesion demonstrating borderline to malignant characteristics. The patient underwent a TAH and BSO. Post-operative histopathology demonstrated two adjacent, but not admixed lesions. The smaller lesion was a benign cystic teratoma and the larger lesion was a Stage 1A malignant Brenner tumour. No further treatment was required. Collision tumours are uncommon. They represent two histologically distinct lesions within the same organ but no mixing of cell types. Diagnosis can sometimes only be made post-operatively but in this case was suspected from the initial ultrasound scan. This case is even more unusual as Brenner tumours are rare ovarian tumours which are mostly benign with only 2%–5% demonstrating malignant change.