sharklasers said:
How do you distinguish between fibrocystic change and a fibroadenoma? i guess if the patient is above 35, it would be fibrocystic change, but what about the 25-35 range?
Pvtbacon has listed the important clinical points: Age >35 (FC) vs. age <25 (FA), tender (FC) vs. non-tender (FA), multiple & bilateral (FC) vs. solitary (FA). Unfortunately, none of them are definitive enough to separate fibrocystic changes from fibroadenoma. So we turn to pathology:
Epithelial lesions of the breast can be malignant (carcinoma of the breast) or benign. Benign epithelial lesions of the breast (given the umbrella term "fibrocystic changes") can be non-proliferative or proliferative. Fibroadenoma, on the other hand, is a benign stromal tumor. So what we are comparing is a benign epithelial "condition" (fibrocystic changes) vs. a benign stromal tumor (fibroadenoma). Morphologically, fibrocystic changes show: (1) Cysts -as the name suggests- (which can be lined by atrophic or metaplastic apocrine cells, giving the "blue dome appearance", (2) fibrosis, and (3) adenosis (increase in # of acini). Fibroadenoma, on the other hand, has a cellular, myxoid stroma -not surprising, since it is a tumor derived from stroma-, which can compress the epithelium (giving the slit-like appearance) or become hyalinized. Epithelial cells found in fibroadenoma are not neoplastic; stromal cells are.
Summary: Fibrocystic changes: Benign epithelial lesion; fibroadenoma: benign stromal tumor. Now based on this, think about this question:
A 37 year old woman presents to the outpatient clinic with a self-discovered mass in her right breast. Physical examination reveals a non-tender but "lumpy-bumpy" right breast. Upon further radiological investigation and biopsy, the sample is assessed for a G6PD isoenzyme analysis. What would you think if the analysis showed the epithelial cells sharing the same G6PD isoenzyme? What if stromal cells shared the same G6PD isoenzyme?
Out of curiosity, are you just finished with your preclinical years or have you done more (i.e. clinical years or entered practice)?
I'm a graduate and I had to perform a mandatory service. But I'm glad I'm done.
Any non-conjugated polysaccharide vaccine only generates IgM immunity. This happens from circulating antigen from the vaccine directly running into/activating membrane-bound IgM on a B-cell that fits it. This is why it's "T-cell independent".
Here's what I don't get: what if somebody gets the vaccine, but they coincidentally don't have any B-cells with receptors that fit the antigen? I assume this is why it doesn't work in babies, but isn't there a chance that some adults just never made the right receptor also? I don't know, I'm probably overthinking this.
Welcome to the world of antigen diversity
How does the immune system respond against millions and millions of different types of antigens? A large section of immunology is devoted to answering that very question. What happens is our bodies generate a very large repertoire of B-cells through recombination of Ig genes (and various other mechanisms). Now, once these cells are generated, they don't sit idly by and wait for an antigen to come to themselves. They circulate throughout the body and they're drained into the lymphatic system where they can interact with antigens within the lymph node. They complete a whole tour of the body approximately within 24 hours. So it is very unlikely that the B-cell somehow misses encountering an antigen.
As for the babies, the issue here is about polysaccharide vs. protein antigen. T-cell independent activation is certainly possible by certain polysaccharide antigens like you've mentioned, but it is not a very effective method. Without T-cell interaction, there won't be isotype switching, affinity maturation, memory cell production, etc., which all aid in mounting an effective response. Neonatal immune system is not yet mature, so an immature system using an ineffective method doesn't really work. They can, however, respond to protein antigens: This is why hepatitis B vaccination can be effective in neonates.
