Whipple's Disease Mimicking Sarcoidosis.

Whipple's disease is a rare systemic disease caused by a infection. Although older literature reports a low rate of incidence, case reports continue to rise due to increased awareness of the disease. Classic Whipple's disease presents as weight loss, diarrhea, and arthralgia and may involve the heart, central nervous system (CNS), or any other organ system. Some patients with Whipple's disease do not have the classic signs and symptoms of the disease.  We present a case of Whipple's disease in a patient with poor appetite, weight loss, and granulomatous inflammation of various organs, including the kidneys and spleen, mimicking sarcoidosis. She had presented three years earlier with acute kidney injury (AKI) and hypercalcemia. The renal biopsy revealed diffuse granulomatous interstitial nephritis. Both AKI and hypercalcemia resolved with prednisone; however, her weight loss and decreased appetite continued. The initial positron emission tomography (PET) scan showed increased fluorodeoxyglucose (FDG) avidity in the spleen and large intestine, and the splenic biopsy revealed non-caseating granulomas. A diagnosis of sarcoidosis was made, and she was started on methotrexate with prednisone. Nevertheless, the weight loss and poor appetite were relentless. A repeat PET scan showed increased FDG avidity in loops of the small and large intestines. A small intestinal biopsy revealed positive periodic acid-Schiff (PAS) and negative acid-fast bacilli (AFB) revealing the diagnosis of Whipple's disease. Whipple's disease should be considered in the differential diagnosis of sarcoidosis, especially in those patients worsening on standard immunosuppression.