Great. Most of u got the answer. Both of the cases are intracystic papillary carcinoma.

The H&E slide in the second case is not very good. You can see it more clearly in the p63 stained slide, which demonstrates papillary glandular structure. The pattern is not like solid papillary ca. I discuss a lot about the features of solid papillary ca (SPC) in one case recently. But I cannot find it now.

Intracystic papillary ca is called encapsulated papillary ca (EPC) now. Microscopically, it is characterized by one nodule of papillary ca surrounded by a thick fibrous capsule. The histologic apperance of the papillary proliferation can have any of the features of papillary DCIS. Myoepithelial cells are not present in the papillae of EPC, same as in papillary DCIS. However, in contract to papillary DCIS, myoepithelial cells are also absent in the periphery of the tumor nodule of EPC. This is the most important feature of EPC. See my above two cases. Currently most people consider the lesion is a vaiant of papillary DCIS, even though some think it may represent a low grade invasive carcinoma. Studies have demonstrate that EPCs have excellent prognosis with adequate local therapy alone. One of our fellows recently demonstrated that collagen IV stain may be useful for differential dx of EPC. The stain is positive in EPC, but negative for invasive carcinoma.