Etymology: William S. Frei, German dermatologist, 1885-1943
a test performed to confirm a diagnosis of lymphogranuloma venereum. Killed antigen, originally derived from infected patients, is injected intradermally in one forearm, and a control material is injected into the other arm. If a red, thickened papule develops at the site of injection of antigen, the test result is positive. See also Chlamydia.