Sentence:  “A <WSD>schirrus</WSD> of the favourable kind, may continue a long time almost harmless, unless it compresses the neighbouring vessels pretty much; as is observed by Van Swieten, though that learned physician says, that so long as a <WSD>schirrus</WSD> possesses any part of the body, it is plain there is reason to be in continual dread of something worse succeeding, &c. for whatever incites the motions of the humours, and quickens circulation, as passions of the mind, errors in diet, motions of the body, bruises, falls, fevers, &c. may change a benign <WSD>schirrus</WSD> into a deplorable cancer. 
Meaning of the word marked with <WSD> tags:  A hard swelling of a gland or other organ.