Adult cystic breast lymphangioma is an extremely rare condition, especially in the inner upper quadrant of the breast.

Cystic lymphangiomas of the breast are benign lymphatic malformations.

Cystic lymphangiomas of the breast are typically located in the upper outer quadrant, the tail of Spence, and subareolar area.

Surgical excision with histopathology examination provides definitive diagnosis of cystic lymphangioma.

Complete surgical excision remains the most effective treatment modality for adult cystic lymphangioma of the breast.