Uneven distribution and significant concentration of apocrine metaplasia in lower breast quadrants.

Two hundred human breasts removed for clinical cancer by radical mastectomy were analyzed to determine whether apocrine metaplasia and apocrine cysts have predilective sites in the four mammary quadrants. One block of tissue randomly removed for each quadrant was examined in one or more histologic sections. The results showed a concentration of apocrine metaplasia and apocrine cysts in the lower mammary quadrants (17.5% versus 8.2%), which is highly significant (chi 2 = 15.25; P less than 0.001). The different distribution between breast cancer (showing predilection for the upper quadrants) and apocrine metaplasia is emphasized, together with the highly significant association between apocrine metaplasia and breast cancer. Based on these data, the usefulness of the clinical detection of cysts in the lower mammary quadrants and needle aspiration of their fluid for the morphologic or biochemical diagnosis of apocrine metaplasia in the screening and management of women at risk is suggested.