General clinical presentation: In young women, fibroadenomas are smooth, round or lobulated, tough, well-defined, swollen and mobile, and are called breast mouse, hence the term “mammary mouse”. The diagnosis needs to be made carefully when the mobility is poor. One exception is fibroadenomas that originate from the posterior aspect of the breast because the ducts surrounding the posterior nipple restrict their movement. The good mobility of tumors in young women is due to the softness and flexibility of the envelope as well as the interstitial mammary gland at this age. These typical features are not evident in older women, where the degenerative fibrous degeneration surrounding the tumor reduces its mobility. Fibroadenomas sometimes seen in older women also present as small, stone-like, hard, isolated masses that remain moderately mobile. However, the stone hard component can easily be detected on mammography as arising from calcification. Rare clinical presentation: Very small superficial nodules formed by fibroadenoma-like tissue, 3-4 mm in diameter, are sometimes seen in young women and often remain unchanged for many years. It has been found that small fibroadenomas are present in 25% of normal mammary glands. Tumors are seen to increase in size during pregnancy, occasionally more dramatically. This may be related to the generalized glandular hyperplasia during pregnancy, caused by infarction or interstitial hyperplasia. A small number of fibroadenomas begin to become visible in the latter years of reproductive age and present as isolated masses. The growth rate is rapid. Similar rapid growth occurs between the ages of 13 and 18 years, so that “giant” fibroadenomas are bimodal at both ends of the reproductive years. Postmenopausal fibroadenomas are rare, suggesting that they degenerate along with the degeneration of the breast during menopause. During this process they may become calcified.