Primary diagnosis of Whipple disease manifesting as lymphadenopathy - Use of polymerase chain reaction for detection of Tropheryma whippelii

Whipple disease is a rare, chronic multisystem disease associated with the recently characterized organism Tropheryma. whippelii. Extraintestinal mani festation involving the central nervous system, heart, and joints occasiona lly occurs. Involvement of the abdominal lymph nodes, especially the mesent eric and periaortic nodes, is not uncommon. However, peripheral lymphadenop athy as the sole clinical manifestation of Whipple disease is rare. We desc ribe 2 patients with Whipple disease whose initial manifestation was lympha denopathy. Lymph nodes from both patients showed infiltration of the sinuse s by macrophages containing periodic acid-Schiff-positive, diastase-resista nt, sickle-like structures. Electron microscopic evaluation confirmed the p resence of rodlike organisms. DNA from each sample was amplified by the pol ymerase chain reaction using a specific set of oligonucleotide primers deve loped against the 16S ribosomal PNA coding sequence of T whippelii. The his topathologic features and differential diagnosis of lipogranitlomatous lymp hadenopathy secondary to Whipple disease, as well as use of molecular-based assays, are discussed.