Feulgen DNA content and mitotic activity in proliferative breast disease. A comparison with ductal carcinoma in situ.

Nuclear Feulgen DNA content was measured by cytophotometry and the number of mitoses per 40 high power fields was determined in hyperplastic and atypical hyperplastic lesions of fibrocystic disease in 18 patients, in ductal carcinoma in situ in 14 patients and in ductal carcinoma in situ associated with infiltrating carcinoma in 11 patients. These parameters were also investigated in the hyperplastic lesions accompanying ductal carcinoma in situ and ductal carcinoma in situ associated with infiltrating carcinoma. The nuclear Feulgen DNA content could not discriminate between atypical hyperplasia and ductal carcinoma in situ. Although differences in the mitotic count between hyperplastic and atypical breast lesions were not statistically significant, there was a statistically significant greater mitotic count in ductal carcinoma in situ alone or associated with infiltrating carcinoma. These findings suggest that the mitotic count is useful for the differential diagnosis between atypical hyperplasia and ductal carcinoma in situ. In addition, hyperplastic lesions associated with ductal carcinoma in situ, with or without infiltrating carcinoma, exhibited a statistically significant higher mitotic count than those in benign fibrocystic disease. Hyperplastic breast lesions exhibiting high mitotic counts may indicate the presence of a neighbouring ductal malignancy and suggest an increased proliferative activity in breast tissue in the neighbourhood of malignancy.