S5190 Diagnosis of Whipple Disease in a Patient Misdiagnosed With Seronegative Rheumatoid Arthritis: Uncovering the Cause of Anemia and Positive Occult Blood

Introduction: Whipple’s disease is a rare bacterial infection caused by Tropheryma whipplei and most commonly affects White men of European descent. It can affect not only the gastrointestinal tract, but also the musculoskeletal, cardiovascular and neurological systems. Early diagnosis is key to preventing significant health issues. Case Description/Methods: A 63-year-old man with past medical history of hypertension, hyperlipidemia, atrial fibrillation status post ablation, not on anticoagulation, unexplained congestive heart failure with EF 40%-45% and seronegative rheumatoid arthritis (RA) on upadacitinib presented to emergency department with shortness of breath, diarrhea, and abdominal distension for 3 days. Hemoglobin (Hg) on admission was 10 with a baseline of 12. The patient's last colonoscopy was 3 years prior showing tubular adenoma in cecum and diverticulosis in sigmoid/descending colon. Patient had no prior esophagogastroduodenoscopy (EGD). Guaiac stool was positive. He denied any history of reflux, antacid, NSAID, tobacco or alcohol use. Patient underwent EGD to rule out gastritis, esophagitis, peptic ulcers or arteriovenous malformation. Findings included severe gastritis with erosions in the gastric body and antrum and severe duodenitis in the bulb, third and fourth portion of duodenum. Differentials included Histoplasmosis and Whipple's disease. Pathology showed expansion of the duodenal villi by foamy macrophages and scattered dilated lacteals. The foamy macrophages contained PAS-positive diastase resistant coarse granules, characteristic of Whipple's disease. They were positive for GMS, but morphology is consistent with bacillary forms not the larger ovoid budding yeast of histoplasmosis. Patient started intravenous ceftriaxone for 4 weeks and then transitioned to Bactrim twice a day for 1 year. Patient was taken off upadacitinib and prednisone as his joint pain was likely from Whipple disease and not RA. He lost 30 lbs prior to his diagnosis and gained it back 1 year later. Migratory arthritis and GI symptoms have improved significantly. Pathology report from repeat EGD 1 year later showed 80% reduction in number of foamy histiocytes with pale staining PAS indicative of therapeutic response. Bactrim was extended to 2 years per protocol as there was improvement. Discussion: This case highlights the importance of early diagnosis of Whipple’s disease to prevent widespread damage. It is important to keep Whipple’s disease in the differential especially in patients with seronegative rheumatoid factor with persistent arthritis not improving on immunosuppressive therapy.