Hiya.

Not sure about the false positive thing. But biopsies are generally accurate (I'm not saying they don't have a failure rate, i genuinely dunno). They usually fall within 3 categories, positive, negative and inconclusive. The inconclusive ones tend to be the most time-consuming ones because whilst not the positive or negative outcome doctors are looking for, it means they can still be highly suspect. This is common with biopsies that only take a small part of the tumour/lymph, rather than the entire thing. When they look at biopsies, they're looking at the cell structure. For example, my wife's breast cells came back as highly irregular, thus cancerous. Even amongst the irregular findings, there's varying degrees. I think that's how they decide how aggressive the cancer is. The more irregular, the more aggressive, if i recall correctly.  Not saying this is how it works in all cases, but it's how it was explained to us.

As for finding your primary, your body's lymph system usually drains in a certain way, so if one node is enlarged, and cells are found within, it points to a certain area being the culprit. But as you are finding out, it's not always a straight forward task.

Thanks for your reply

Another problem with cancer, it needs to be a certain size before it will get picked up with scans. So your primary might be very small, thus they can't locate it.

Sometimes the primary is never found. That is usually referred to as cancer/carcinoma of unknown primary [CUP]

Another problem with cancer, it needs to be a certain size before it will get picked up with scans. So your primary might be very small, thus they can't locate it.

Sometimes the primary is never found. That is usually referred to as cancer/carcinoma of unknown primary [CUP]