Clinical history: 58 y/o female, operated on for a large unilateral ovarian cyst (see case 1). Slides are from unaffected ovary.
What is your diagnosis?
Discussion and answers
Diagnosis: Brenner tumour
Ovarian surface epithelial neoplasms composed of transitional (urothelial)-type epithelial cells (benign, low malignant potential (borderline), or malignant (malignant Brenner, transitional cell carcinoma)) comprise approximately 2% of all primary surface epithelial neoplasms. These tumours are thought to arise through metaplasia of the ovarian surface epithelium and are analogous to Walthard nests, which are transitional-type epithelial inclusions occurring beneath the serosa of the fallopian tubes and in the hilar region of the ovaries.
Most transitional cell tumours occurring within the ovaries are benign (Brenner tumours), and are typically incidental findings discovered at laparotomy for unrelated pelvic conditions in patients during the fourth to eighth decades (mean age 50 years).
Benign Brenner tumours are typically solid and unilateral, with a smooth external surface and firm yellow or white cut section containing small cysts (occasionally large cysts are present); they vary in size from < 2 to > 20 cm, but most are < 2 cm and up to one-third are microscopic.
Benign Brenner tumours are composed of well-demarcated nests of cytologically bland transitional-type epithelium enmeshed in prominent fibromatous stroma. Mitotic figures are rare to absent in benign Brenner tumours.
Transitional cell tumours are positive for cytokeratin, EMA, and WT1. Most exhibit a CK7-positive, CK20-negative profile, similar to other primary ovarian-surface epithelial tumours.