Transmission electron microscopy helpfulness in Whipple's disease masked by immunosuppressant therapy for arthritis

A 61‐year‐old woman received a diagnosis of undifferentiated non‐erosive arthritis in 2010 and assumed methotrexate and steroids in 2014. After 1 year, she experienced watery diarrhea, vomiting, fever, weight loss, and severe hypoalbuminemia, thus being admitted into our Unit. Esophagogastroduodenoscopy showed duodenal lymphangiectasia and duodenal biopsy samples several foamy PAS‐positive macrophages and villous subtotal atrophy. Transmission electron microscope demonstrated several extracellular and intracellular rod‐shaped bacteria (Tropheryma whipplei). Therefore, we diagnosed Whipple's disease. Our patient assumed doxycycline/hydroxychloroquine with prompt remission of gastrointestinal symptoms. At 1 year of follow‐up, she was symptom‐free, histological reassessment showed almost complete mucosal healing and transmission electron microscope demonstrated bacteria breaking/disappearance. The present report demonstrates that: (i) rheumatological manifestations are common onset symptoms of Whipple's disease; (ii) immunosuppressive therapy may delay the diagnosis and worsen clinical presentation; (iii) transmission electron microscopy for specific bacteria detection/disappearance is an helpful diagnostic tool, when available.