Biologically, what are Sirchos?
Are they a Tumor?
Mi Yodeya is a question and answer site for those who base their lives on Jewish law and tradition and anyone interested in learning more. It only takes a minute to sign up.Sign up to join this community
As Rabbi Yaacov Dovid Lach explains in his book Chullin Illuminated they are a fibrous adhesion that connect parts of the lungs to each other or to the surrounding walls of the chest cavity. In healthy lungs they are not present and thus indicate a problem. The exact nature of this problem is a matter of dispute (it either is caused by a previously present wound healing but the wound can be expected to reopen, or the adhesion could cause a tear in the lung in the future as these parts of the lung are supposed to free standing to allow for the expansion and contraction of breathing).
Adhesions themselves can be caused by wounds or infection, so either side of the dispute is a plausible explanation of the adhesion. However, modern biology seems to attribute them in cattle to infection, thus favoring the notion that the problem is a future tear in the lung, not a past one.
The general condition in cattle is described as lung leasions. Here is a link with pictures of several different ways that it presents. WARNING: Some may find such images disturbing. Link.
I wasn't able to find a discussion of whether or not modern biology considers holes in lungs a possible outcome of lung leasions.