['To study the relationship of mammographic appearance of nonpalpable breast cancer to the pathologic characteristics.', 'The mammographic appearance of nonpalpable breast cancer may be associated with pathologic variables having prognostic significance, which could influence clinical management.', 'The authors correlated the mammographic appearance and pathologic characteristics of 543 nonpalpable malignancies diagnosed in a single institution between July 1993 and July 1999. Cancers were divided into four groups based on mammographic presentation: mass, calcification, mass with calcification, and architectural distortion.', 'The majority of masses (95%), masses with calcifications (68%), and architectural distortions (79%) were due to invasive cancers, whereas the majority of calcifications (68%) were due to ductal carcinoma in situ (DCIS). Among invasive cancers, calcifications were associated with more extensive intraductal carcinoma, more Her2/neu immunoreactivity, and more necrosis of DCIS. Lymphatic invasion was more common in cancers presenting as a mass with calcifications. Sixty-nine percent of DCIS associated with invasive cancers presenting as calcifications were of high grade according to the European Organization for Research and Treatment of Cancer. Calcifications in noninvasive tumors were associated with necrosis in DCIS. Two thirds of cancers presenting as architectural distortion had positive margins (65%) compared with 35% to 37% of other mammographic presentations. Mammographic presentation was not significantly related to tumor differentiation or estrogen or progesterone receptor status. The ratio of invasive to noninvasive malignancies increased progressively with increasing age from 1:1 in patients younger than 50 years of age to 3:1 in patients older than 70 years, whereas the proportion presenting as calcifications declined from 63% in patients younger than 50 years to 26% in patients older than 70 years.'] Does mammographic appearance of nonpalpable breast cancer reflect pathologic characteristics?