What is the etymology of sarcomatoid?

The elements of the word are Greek, although the word itself probably ever existed in Greek. In Greek, "sarkoma" simply meant a fleshy growth, a combination of "sarx," flesh (the same element as in "sarcophagus") and the suffix "-oma," which originally just made an abstract noun of a verb but now means specifically a tumor. (Why it was added to nouns as well is something of a puzzle.) So today "sarcoma" means specifically a cancer. The stem of the Greek word "sarkoma" (the form to which other endings would be added) is "sarkomat-." The "-oid" suffix ("-oeides" in Greek) means "like" or "resembling." (The "droids" in the Star Wars movies are actually "androids"--manlike beings.) So "sarcomatoid" means "cancer-like" or "resembling cancer.".