What common feature is associated with fibrocystic breast changes?

Bilateral mobile cystic masses that are often tender are indeed a common feature associated with fibrocystic breast changes. This condition is characterized by the presence of multiple cysts that can fluctuate in size and tenderness, especially during the menstrual cycle. The term "fibrocystic" indicates that there are both fibrous and cystic (fluid-filled) components within the breast tissue.

These masses are typically well-defined, and their mobility is a significant distinguishing characteristic; they can easily be moved under the skin when palpated. The tenderness often results from hormonal fluctuations, particularly related to the menstrual cycle, which can lead to heightened sensitivity and discomfort in the breast tissue.

The other options presented do not accurately capture the features of fibrocystic changes. Firm, immobile lumps can be indicative of other breast conditions and are not typically associated with fibrocystic changes. Constant pain in both breasts might suggest a different underlying issue rather than the cyclical tenderness characteristic of fibrocystic conditions. Lastly, the development of unusual skin patches is not a typical symptom of fibrocystic changes and may suggest other dermatological or breast conditions instead.