Breast bud tenderness or Thelarche: This is the most common cause of breast lumps in prepubescent girls, associated with the onset of puberty. It presents as tender breast enlargement and is a normal physiological process.

Fibroadenoma: A common benign breast tumor in adolescents, often presenting as a firm, mobile, and sometimes tender lump.
Cyst: Breast cysts can occur in adolescents and may cause pain, especially if they become large or rupture.
Infection or Abscess: Breast infections can cause painful lumps and are more common in adolescents, especially if there is a history of trauma or nipple piercing.
Fat Necrosis: Trauma to the breast can cause fat necrosis, leading to a painful lump.

Breast Cancer: Although extremely rare in children, breast cancer must be considered to avoid delayed diagnosis. It is crucial to investigate any unusual or persistent symptoms.
Phyllodes Tumor: These are rare tumors that can be benign, borderline, or malignant. They tend to grow quickly and can cause pain.
Potts Disease (Tuberculous Mastitis): In areas where tuberculosis is common, Potts disease can cause breast lumps and pain.

Hematoma: A collection of blood outside of blood vessels, which can occur after trauma and cause a painful lump.
Lipoma: A benign tumor composed of fat tissue, which is rare in the breast of a prepubescent girl.
Hamartoma: A benign growth that can occur in the breast, composed of a mixture of glandular, fibrous, and fatty tissues.
Neurofibroma: Part of neurofibromatosis type 1, which can rarely present as a breast lump in children.