Radiologic appearance of nonpalpable intramammary lymph nodes.

Sixty-four well circumscribed nonpalpable lesions, mammographically evaluated as benign and cytomorphologically verified as lymph nodes, were studied concerning mammographic appearance, size and location within the breast. The great majority, 72%, were situated within the upper-outer quadrant, but lymph nodes were also diagnosed in other areas of the breast. Of the verified lymph nodes 50 (78%) had a lower density at the center than at the periphery. These were the only well circumscribed nodules with a low density center observed in a total of 3,623 nonpalpable lesions stereotaxically needled during the same period. Three of the lymph nodes were verified histopathologically. Till now, none of the other 61 lesions has turned out to be a malignant tumor during a follow-up time from 9 to 15 years. Thus a lesion presenting roentgenologically as a well circumscribed nodule with a central area of decreased density compared to the peripheral part can be confidentially diagnosed as a lymph node by the mammograms alone and no further investigation is indicated.