Breast cysts are fluid filled, round or ovoid masses derived from the terminal duct lobular unit (TDLU). Cysts begin as fluid accumulation in the TDLU as a consequence of distension and obstruction of the efferent ductule (11). Breast cysts are influenced by hormonal function and therefore typically develop in premenopausal and perimenopausal women as a consequence of lobular development, cyclic changes, and lobular involution (12).
Microscopically the cyst inner lining is flat or completely denuded and myopeithelial layer is recognizable.
Cysts are mostly occurs in women between 35-50 years old. It is uncommon for postmenopausal women to develop breast cysts, unless they are taking postmenopausal hormone replacement