Fig. 2

Microscopic and immunohistochemical examinations for the right breast lesion. a A large papillary lesion was present within a dilated duct. b Groups of cribriform basaloid cells were present within the thickened fibrous septae adjacent to the papillary lesion, which showed bland basaloid cells with prominent cribriform architecture, intraluminal mucin and foci of sebaceous differentiation. c High power examination of the papillary lesion revealed similar basaloid cells with area of sebaceous differentiation. d Periphery of the papillary lesion showed intact layer of myoepithelial cells. e Immunostain for p63 and (f) CD117 in glandular structures showed positivity for dual population of myoepithelial cells and luminal epithelial cells. g Immunostain for p63 (g) and (h) CD117 in the papillary lesion also highlighted dual population of myoepithelial cells and luminal epithelial cells. i Both the glandular structures and the (j) papillary lesion were also positive for SOX10 immunostain. (Hematoxylin-eosin, original magnification ×2 [a], × 20 [b], ×40 [c, d]; Immunohistochemistry, original magnification × 20 [e, f, g, h]. × 20 [i, j])