Granulosa cell tumors in mares are commonly associated with increased production of which hormone?

• A. Estrogen
• B. Testosterone
• C. Progesterone
• D. Cortisol

Answer: (A)

Granulosa cells in the ovary are the cells that normally produce estrogen. When a granulosa cell tumor develops, these cells continue and often increase estrogen production, leading to signs driven by estrogen excess such as persistent estrus, vulvar edema, and even stallion-like behavior in mares. That’s why the hormone commonly elevated with these tumors is estrogen. The other hormones listed are not typically produced in excess by granulosa cell tumors—testosterone relates to different tumor types or tissues, progesterone to luteal or placental sources, and cortisol to the adrenal gland.