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 manifestation involving the central nervous system, heart, and joints occasionally occurs. Involvement of the abdominal lymph nodes, especially the mesenteric and periaortic nodes, is not uncommon. However, peripheral lymphadenopathy as the sole clinical manifestation of Whipple disease is rare. We describe 2 patients with Whipple disease whose initial manifestation was lymphadenopathy. Lymph nodes from both patients showed infiltration of the sinuses by macrophages containing periodic acid-Schiff-positive, diastase-resistant, sickle-like structures. Electron microscopic evaluation confirmed the presence of rod-like organisms. DNA from each sample was amplified by the polymerase chain reaction using a specific set of oligonucleotide primers developed against the 16S ribosomal RNA coding sequence of T. whippelii. The histopathologic features and differential diagnosis of lipogranulomatous lymphadenopathy secondary to Whipple disease, as well as use of molecular-based assays, are discussed.