 Welcome back to our USMLE Question of the Day with MedSmarter. Let's get to the question. As always, we start with the last sentence, which is the question of the vignette, and then we know what the question is going to be asking us. Which of the following would most likely be found in the biopsy of this mass? A 20-year-old woman presents to her physician's office with a small, firm mass in the lower, inner quadrant of her right breast that seems mobile when palpated. It is not tender. There are no overlying skin changes or nipple discharge. She has no family or personal history of breast cancer, so which of the following would most likely be found on biopsy of this mass? Take a minute, read the question again and the answer choices, come up with your answer, and put it in the comment box below. Okay, so the first thing we're going to do is we're going to find the things that are most important for us in this question. So age, 20-year-old female has a small, firm mass, and the location is in the lower, inner quadrant of her right breast. It is mobile. It is non-tender. Then there's no skin changes or nipple changes associated with this. We can also see that there's no personal or family history of breast cancer, so we don't have some risk factors. So let's look and see what could our possible answers be. Starting at the top with A, blue dome cysts and some atypical epithelial hyperplasia. Blue dome cysts are classically found with fibrocystic change of the breast, and I don't believe this is fibrocystic change of the breast, so I'm going to eliminate answer A. B, cells in a single file form. That is classic for infiltrating lobular carcinomas. I don't think this is a carcinoma at all. I think this is probably more like a fibroadenoma, so we're going to mark out B because this is not a classic cancer presentation. C, fibrosin stroma around normal-looking glands. That is a very good example of what a fibroadenoma is because they're small, firm, mobile masses, so they have normal glands around them with some fibrostoma. So I think C might be my answer. Let's continue on and read the rest of our answers first. D, large cells with clear halos. That's pageus disease. No, this is not pageus disease of the breast because of the skin. There's no skin changes. And then E, multicentric lobes with lymphocytic infiltrates. Lymphocytic infiltrates are classic of a bad prognosis with a cancer specifically, and I don't believe that's what we're dealing with, so we're going to mark E out, which leaves us with our final answer of C, which is a fibrosin stroma around normal-looking glands. And the correct answer is C, which is fibrosin stroma around normal-looking glands. What this is indicative of and what this question is telling us is a fibroadenoma. These are benign changes, typically in young females in the breast. It's a common tumor. They are classically described as small, firm, and mobile masses. We don't have any association with malignancy with these, and if you did a biopsy, you would see the fibrosin stroma with a normal ducts and normal glands. These blue dome cysts in A are seen with fibrocystic diseases of the breast, and specifically fibrocystic diseases of the breast do increase our risk of carcinoma. B, cells in a single file formation, as we mentioned earlier, is infiltrating lobular carcinomas. So you see either clustered or linear formations with these cells. Answer D, this is Padgett's disease. And with Padgett's disease, you do often see some skin findings associated with the development of this disease. And then finally, E, these are anytime you, like I said earlier, anytime you see any lymphocytic infiltrates, that is an inflammatory carcinoma, and that inflammatory carcinoma has poor prognosis.