Several variants of fibrocystic breast changes may be distinguished and may vary in cause and genetic predisposition. Adenosis involves an abnormal count and density of lobular units, while other lesions appear to mainly arise from ductal epithelial origins. Theres evidence that iodine deficiency contributes to fibrocystic breast changes by enhancing breast tissue sensitivity to estrogen. Diagnosis
This is an exclusion diagnosis, mostly done based on the clinical presentation after ruling out breast cancer. Nipple fluid aspiration can be used as a classification cyst type method (and to some extent improve breast cancer risk prediction) but its rarely used in practice. Biopsy or fine needle aspiration are rarely warranted.Fibrocystic breast disease is primarily diagnosed based on the symptoms, clinical breast exam and physical exam. During this examination, the doctor looks for unusual breast areas, both visually and manually. Also, the lymph nodes located in the axilla and lower neck are examined. A complete and accurate medical history is also helpful in the diagnosing process. If the patients medical history and physical exam findings are consistent with normal breast changes, no additional tests are needed; otherwise the patient will be asked to return a few weeks later for reassessment. Women may detect lumps in their breasts during self-examination, if this happens its strongly advised to visit a health professional right away. Imaging
In order to establish whether the lump is a cyst or not, several imaging tests may be performed, these may include: mammography, X-rays, MRIs and ultrasound studies.
The strength of the family history of breast cancer, available for 4808 women, was a risk factor that was independent of histologic findings. No increased risk was found among women with no family history and nonproliferative findings. In the first 10 years after the initial biopsy, an excess of cancers occurred in the same breast, especially in women with atypia." It is not well understood whether the lesions are precursors of breast cancer or only an indication of increased risk, for most types of lesions the chance of developing breast cancer is nearly the same in the affected and unaffected breast (side) indicating only coincidence of risk factors. For atypical lobular hyperplasia there is high incidence of ipsilateral breast cancers indicating a possible direct carcinogenetic link. Epidemiology
The estimated prevalence of fibrocystic breast changes in women over their lifetime vary widely in the literature, ranging from 30 to 60% over about 50 to 60% to about 60 to 75% of all women.The condition is most common among women between 30 and 50 years of age. Terminology
In ICD-10 the condition is called diffuse cystic mastopathy, or, if there is epithelial proliferation, fibrosclerosis of breast. Other names for this condition include chronic cystic mastitis, fibrocystic mastopathy  and mammary dysplasia. The condition has also been named after several people (see eponyms below). Since it is a very common disorder, some authors have argued that it should not be termed a "disease", whereas others feel that it meets the criteria for a disease.