In the 'needle core biopsies" generally, a large bore needle is used and the operator, mostly a pathologist (medically trained) will feel the lump or lesion, hold it between his fingers and push the needle through the numb skin several times to get pieces of tissues and cells and then spread them out on a slide, or create "cell blocks" that re-capitulates the original tissues, this is a CYTOLOGICAL technique.
In the "tissue core biopsies", a special designed large bore cutting needle is used to get to deeper lumps not felt by the hand, but rather seen on ultrasound,and using a device that locates it, the trucut needle goes in and cuts out a piece of the tissue in the form of a cylinder (resembling the bore of the large needle), these are actual tissue samples and not cells, fragments or fine particulate matter from the lump. The tissue is processed as such and read as biopsies as done in HISTOLOGY as compared to the previous methodology called cytology.
The second METHOD of core biopsy is much more accurate, as it provides the tissue and the entire configuration of the lesion (cancer, adenoma, etc) within the tissue matrix. One can check online resources to see papers published on this topic.
PROSTATE INTRA-EPITHELIAL NEOPLASIA IS the weed you saw in the small garden patch, but it has not spread as yet, or let's say, there is cancer within the prostate and they mention PIN, it means they have identified the original early cancer that was confined to the glands of the prostate in the midst of this cancer that has broken through. Generally, if the core biopsies only show a PIN, there is no way to tell if this is going to become cancer and break out or be confined to the gland.The PIN cells look like the cancer cells, but have not broken through as yet. This is not the same in the Breast called DCIS, where if present, there will be surgical action taken to remove the whole area in its entirety.