| Glandular | Tumor is composed of glands. | Figure 3A |
| Acinar | Tumor is composed of small glandular clusters with small lumens. While this is a subclass of glandular, it is very characteristic of MMTV-induced tumors. | Figure 3B |
| Cribriform | Tumor is composed of sheets or nests of cells forming lumens with round, punched out spaces.. | Figure 3C |
| Papillary | Tumor has finger-like projections composed of epithelium covering a central fibrovascular core. | Figure 3D |
| Solid | Tumor is composed of solid sheets of epithelial cells with little or no glandular differentiation. | Figure 3E |
| Squamous | Tumors composed solely of squamous cells with or without keratinization, absence of glandular pattern. | Figure 2E |
| Fibroadenoma | Tumor is composed of a proliferation of both myxoid fibrous stroma and glands. | Figure 3G |
| Adenomyoepithelioma | Tumor is composed of myoepithelium and glands. | Figure 2F |
| Adenosquamous | Tumor has both glandular and squamous differentiation. | Figure 2C |
| Not Otherwise Specified (NOS) | Tumor does not have any of the other common descriptor patterns. |
NOTE: The images noted in these and other tables can be viewed by clicking here.