[Whipple's disease. Histologic diagnosis after the discovery of Tropheryma whippelii]

Since the microbiological discovery of Tropheryma whippelii, Whipple's disease has attracted to new attention in clinical medicine. As small intestinal biopsy is the diagnostic procedure, the impact of knowledge about the histopathological features of Whipple's disease and its differential diagnosis has increased. PAS-positive macrophages in the intestinal mucosa are the diagnostic hallmark, but further subtyping of cells is important. In Whipple's disease macrophages with intensely PAS-positive granular particles in the cytoplasm (type 1) should be distinguished from cells with faintly PAS-positive cytoplasm without granular particles (type 3). The latter type of macrophages may persist even for many years but does not affect a diagnosis of intestinal remission. However, as systemic infection with T. whippelii is common, but intestinal biopsy specimens are not representative for other organs, additional investigations are performed. These include analysis of the cerebrospinal fluid by means of cytology and polymerase chain reaction, even in patients without neurological symptoms. For ascertaining eradication of T. whippelii in the cerebrospinal fluid, polymerase chain reaction is more reliable than cytology.