A 49-year-old male was referred to our hospital for chronic diarrhea and weight loss.

Patient was previously treated for articular rheumatism with immunosuppressive therapy for 7 years without significant benefit.

Upon admission, hypochromic microcytic anemia, low serum cholesterol, elevated C-reactive protein and erythrocyte sedimentation rate were observed. Anti-transglutaminase antibodies were normal. Computed tomography (CT) showed multiple intra and retroperitoneal lymphadenopathy suspicious of lymphoma, admixed with some fatty tissue areas. Ultrasonography (US) performed to obtain fine-needle biopsy failed to demonstrate a target lesion, but the retroperitoneum appeared thickened by a diffuse non-homogeneous, hyperechoic fatty-like tissue (Figures 1A and B). Endoscopy showed erythema and erosions of the duodenum. Histology of duodenal biopsies showed modifications suggestive of Whipple's disease (WD) (Figures 2A and B), confirmed by specific polymerase-chain-reaction. The patient was given twice daily sulfametoxazole/trimetroprim for one year. The symptoms improved after 3 weeks of treatment and completely disappeared after 3 months. Follow-up CTs showed a progressive reduction of lymphadenopathy.

WD is a chronic multi-organ infectious disease caused by Tropheryma whipplei, commonly affecting middle-aged white men. About 1000 cases have been reported. Tropheryma whipplei is a ubiquitous pathogen. The transmission mode is still unclear although faecal-oral way has been suggested. The decreased production of interleukin-12 with reduced release of interferon-gamma by T-cells and defective macrophage activation might represent the predisposing pathogenetic mechanism. Several studies have shown that macrophages accumulating within the lamina propria appear unable to degrade phagocytosed bacteria.

WD may interest every organ. Gastrointestinal involvement occurs in 70% of cases with weight loss, diarrhoea and abdominal pain. Extraintestinal manifestations can involve joints, heart, lymphatic system, skin and central nervous system. WD is characterised by a long-lasting prodromal stage with variable and non-specific symptoms and a steady state frequently including weight loss and diarrhea. No serum or radiological findings are specific of WD. Sometimes endoscopy show erosive bulbitis or duodenitis. Immunohistochemistry allows the detection of Tropheryma whipplei in different bodily samples.

Differential diagnosis includes rheumatic disease, coeliac disease, sarcoidosis, lymphoma, Addison's disease and neurologic disorders. Disease identification is essential to avoid immunosuppressive therapy which has been observed to be associated with a rapid clinical deterioration in WD.

Our case confirms that WD should be considered as differential diagnosis in patients with gastrointestinal symptoms and arthropathy, especially in middle-aged men. In contrast with CT suggesting lymphoproliferative disease, US showed images consistent with fat deposits, a feature typically described in Whipple's disease. Findings of low density, highly fatty lymph nodes with a marked hyperechoic pattern in the mesentery and retroperitoneum may be associated with WD. An appropriate therapy can obtain clinical remission. However, it is well known that clinical relapse after treatment discontinuation may occur in 2-33% of cases after an average time of 5 years. Presently, optimal duration of the antibacterial treatment and follow up strategies are not yet well established. Further studies are needed to clarify these unresolved issues.