[2] Brenner tumours very rarely can occur in other locations, including the testes.

[3] On gross pathological examination, they are solid, sharply circumscribed and pale yellow-tan in colour.

Histologically, there are nests of transitional epithelial (urothelial) cells with longitudinal nuclear grooves (coffee bean nuclei) lying in abundant fibrous stroma.

The coffee bean nuclei are the nuclear grooves exceptionally pathognomonic to the sex cord stromal tumour, the ovarian granulosa cell tumour, with the fluid-filled spaces Call–Exner bodies between the granulosa cells.

Histologically, Leydig cell tumours of the testes and ovarian stromal Leydig cell tumours (ovarian hyperandrogenism and virilization) both have characteristic Reinke crystals.