Which type of ovarian tumor is likely to produce estrogen and cause precocious puberty in an 8-year-old girl?

A granulosa cell tumor is a type of sex-cord-stromal tumor that can produce estrogen. These tumors arise from the granulosa cells of the ovarian follicles and have the ability to secrete estrogen due to their cellular characteristics. In prepubertal girls, elevated estrogen levels can lead to early sexual maturation or precocious puberty, which is the premature development of secondary sexual characteristics.

Granulosa cell tumors are particularly significant in this context because they are known to cause increased estrogen production, manifesting in symptoms such as breast development and menstruation in young girls. The hormonal effects can lead to rapid changes associated with puberty, thus causing precocious puberty.

Other ovarian tumors listed do not typically produce significant amounts of estrogen or are less common in this age group. For instance, cystadenocarcinomas and fibromas are not primarily associated with estrogen production, and dermoid cysts (teratomas) contain diverse tissue types but do not usually secrete hormones leading to precocious puberty. The specific estrogen-secreting capability of granulosa cell tumors makes them the most likely cause in this scenario.