Galactorrhea: This condition is characterized by the spontaneous flow of milk from the breast, unassociated with childbirth or nursing. It can be caused by various factors including hormonal imbalances, certain medications, or issues with the pituitary gland. The presence of a milky discharge from both breasts, especially if it's spontaneous and not related to childbirth or breastfeeding, points towards galactorrhea as the most likely diagnosis.

Hyperprolactinemia: Elevated levels of prolactin can cause galactorrhea. This condition can result from various causes, including pituitary tumors, thyroid disorders, or certain medications. The symptoms of hyperprolactinemia, including galactorrhea, make it a likely diagnosis for milky discharge from both breasts.
Prolactinoma: A type of pituitary tumor that secretes prolactin, leading to hyperprolactinemia and potentially galactorrhea. Given its direct link to prolactin levels and galactorrhea, it's considered a likely diagnosis.
Hypothyroidism: In some cases, hypothyroidism can lead to an increase in prolactin levels, resulting in galactorrhea. Although less common, it remains a possible cause for milky discharge from the breasts.

Pituitary Macroadenoma: A larger pituitary tumor that can cause an overproduction of prolactin, leading to galactorrhea. It's crucial not to miss this diagnosis due to the potential for the tumor to compress surrounding structures, leading to serious complications.
Breast Cancer: Although rare, certain types of breast cancer, such as invasive ductal carcinoma, can present with nipple discharge. It's essential to rule out breast cancer due to its severe implications and the need for prompt treatment.

Idiopathic Galactorrhea: Galactorrhea without an identifiable cause. While it's a diagnosis of exclusion, it remains a possibility if other causes are ruled out.
Neurogenic Galactorrhea: Caused by conditions affecting the nervous system, such as spinal cord injuries or thoracic surgery, which can lead to galactorrhea. This is less common but should be considered in patients with relevant medical histories.
Ectopic Prolactin-Producing Tumors: Rare tumors outside the pituitary gland that produce prolactin, potentially causing galactorrhea. These are uncommon but represent a rare cause of galactorrhea that should not be overlooked.