Columnar alteration with prominent apical snouts and secretions - A spectrum of changes frequently present in breast biopsies performed for microcalcifications

We have noted in breast biopsies performed for microcalcifications a spectr um of lesions in the terminal duct lobular unit (TDLU) characterized by col umnar epithelial cells with prominent epical cytoplasmic snouts, intralumin al secretions, and varying degrees of nuclear atypia and architectural comp lexity. The appearance of some of these lesions is worrisome, but diagnosti c difficulties arise because the histologic features do not fulfill establi shed criteria for the diagnosis of atypical ductal hyperplasia or ductal ca rcinoma in situ (DCIS). We have termed such lesions columnar alteration wit h prominent apical snouts and secretions (CAPSS). The purpose of this study was to define the pathologic spectrum and mammographic features of these l esions. We reviewed histologic sections and mammograms from 100 consecutive breast biopsies performed for microcalcifications. The prevalence and hist ologic features of CAPSS and the association with other histologic findings were recorded. CAPSS was identified in 42% of cases. At the lower end of t he spectrum were lesions similar to columnar alteration of lobules but in w hich apical cytoplasmic secretion and nuclear stratification were more pron ounced and cells with a hobnail configuration were common. More advanced le sions showed columnar epithelial cell tufts, bridges, and micropapillations with prominent apical cytoplasmic snouts and with greater degrees of nucle ar stratification and atypia. At the upper end of the spectrum were lesions that could arguably be considered DCIS. Calcifications were present within CAPSS in 74% of cases, were frequently psammomatous, and were typically no nbranching and often round on mammography. Columnar alteration of lobules w as more common in biopsies with than without CAPSS (74 versus 36%, p < 0.00 1). Ductal carcinoma in situ was seen with similar frequency in biopsies wi th and without CAPSS (38 versus 41%). However, DCIS in cases with CAPSS was more often of the low-grade micropapillary-cribriform type than in cases w ithout CAPSS (56 versus 17%, p < 0.01), and CAPSS and DCIS commonly coexist ed in the same or adjacent TDLUs. In conclusion, 1) CAPSS encompasses a spe ctrum of lesions bounded at the lower end by columnar alteration of lobules and at the upper end by low-grade DCIS. Lesions recently described by Page as "hypersecretory hyperplasia with atypia" fall within this spectrum. 2) Some CAPSS lesions present architectural or cytologic features that create diagnostic difficulties and raise the possibility of atypical ductal hyperp lasia or DCIS; however, the level of cancer risk associated with CAPSS lesi ons that do not fulfill established criteria for atypical ductal hyperplasi a or DCIS is unknown and requires evaluation in follow-up studies.