The natural history of macroscopic cysts in the breast.

Macroscopic cysts of the breast, defined as clinically apparent lesions, are common causes of masses in the breast. In a 14 year study of 4,207 patients, cysts in the breast were diagnosed by percutaneous aspiration in 286 women who had cysts on 561 occasions. These cysts accounted for the presenting problem in 4 per cent of 15,600 visits to the clinic. Patients with cysts were observed for a mean period of 70 months. The patient was aware of a mass 83 per cent of the time, but cysts were discovered in asymptomatic patients in 17 per cent. The majority of cysts (76 per cent) were in premenopausal women (mean age of 48 years), with peak occurrence between age 40 and 50 years. Only 5 per cent were in women who were more than 60 years of age, none of whom had concurrent or subsequent carcinoma. Cysts did not recur in 60 per cent of the patients. There were two to five recurrences in 36 per cent and more than five recurrences in 4 per cent. Patients with more than five recurrences were five years younger than the over-all group when the first cyst appeared and the events developed over a period of time ranging from 51 to 161 months (mean of 96 months) and appeared at intervals averaging 17 months. Only three patients who were postmenopausal had more than one cyst. Carcinoma occurred in three patients (1 per cent) diagnosed between three and five years after the first cyst was discovered. Macrocystic disease seems to be a condition of women who were perimenopausal. An association between these cysts and carcinoma has not been proved.