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DOI: 10.1055/s-0032-1313850
Is the bacterium Tropheryma whipplei cause of the disease in a subgroup of patients with presumed sarcoidosis?
Introduction: Sarcoidosis is a granulomatous multiorgan disease of unknown cause. Recently we published a case report presenting a patient in whom a causal relationship between pulmonary sarcoidosis and infection with Tropheryma whipplei (T. whipplei) could be demonstrated1. To our best knowledge this is the first systematic study investigating the hypothesis, that in a subgroup of patients presumed sarcoidosis is caused by T. whipplei.
Patients and Methods: A total of 56 consecutive patients in whom a diagnosis of sarcoidosis was suspected clinically and confirmed histologically were included in this retrospective study. The study population comprised 21 male and 35 female patients, mean age±SD=53.6±16.2 (range 24–90) years.
PCR-examination for T. whipplei (which detects species-specific bacterial-ribosomal RNA) was performed in all patients, using formalin-fixed and paraffin-embedded specimens obtained from organs affected by sarcoidosis. Specimens were obtained from the following tissues: lung (n=22), lymph nodes (n=15), skin (n=7), liver (n=6) and other organs (n=6). All PCR-examinations were done in an international reference laboratory for Whipple's disease with extensive experience in this field.
Results: T. whipplei-RNA was detected in tissues affected by sarcoidosis in 2 of 56 patients (3.6%). Both patients with a positive PCR were women (age: 32 and 85 years, respectively) and had enlarged mediastinal and hilar lymph nodes. Histological examination of affected lymph nodes showed granulomatous lymphadenitis of sarcoid type, PAS-staining was negative. Both patients had no gastrointestinal symptoms. Further evaluation for the presence of Whipple's disease in these two patients is ongoing.
Conclusion: Our findings contribute further evidence to the hypothesis, that in a subgroup of patients presumed sarcoidosis is caused by infection with the bacterium T. whipplei. However, this hypothesis should be further evaluated in prospective studies.
1 Dzirlo L, Hubner M, Müller C, Blaha B, Formann E, Dellinger C, Petzelbauer P, Müllauer L, Huber K, Kneussl M, Gschwantler M. A mimic of sarcoidosis. Lancet 2007; 369:1832.