[The dangers of mammography in diagnosing a palpable lump in the breast]

The success of mammography screening programmes in the detection of unsuspected and impalpable breast cancer has led to reliance on a negative mammographic report as assurance that no malignancy is present even in palpable breast lumps. Pre-operative mammography was performed on 38 patients with palpable lumps who were subsequently proven by histology to have carcinoma of the breast. In 4 patients (10.8%) the mammogram was negative; 3 were also assessed as benign clinically. In 5 cases (13.5%) the report was negative but biopsy was recommended; 3 of the 5 were assessed as benign clinically. Therefore, in 9 of the 38 patients (24%) malignancy was not diagnosed unequivocally on mammography, although 3 of these patients had clinical stigmata of malignancy. Twenty-nine patients (76%) were diagnosed correctly by mammography; 5 of these cases were assessed as benign clinically. Six of the 38 cases (16%) were thought to be benign on both mammography and clinical examination. Thus, even confirmation by mammography that a breast lump without clinical signs of malignancy is indeed benign, does not rule out the possibility of carcinoma.