Intravenous Tamm-Horsfall protein polyps: report of a case in association with a hematoma that mimicked a renal neoplasm.

Tamm-Horsfall protein (THP) is a glycoprotein produced only in the thick ascending limb of the loop of Henle. Its primary physiological function is unknown, but it may have a role in host defense against infectious organisms. THP is the primary scaffolding protein in all varieties of tubular casts.