This Rare Disease Can Be Misdiagnosed as Rheumatoid Arthritis

Whipple’s disease (WD) is an uncommon disease that is caused by the bacteria known as Tropheryma whipplei. Infection with T. whipplei bacteria causes damage to the villi, which are the tissues that are responsible for absorbing nutrients in the small intestine. This, in turn, leads to digestion interference by obstructing the breakdown of foods and blocking the body’s ability to absorb necessary nutrients. Whipple’s disease mainly affects the gastrointestinal system but it can also affect other organs such as the heart, lungs, joints, skin and brain.

Common signs and symptoms of Whipple's disease

The most common signs and symptoms of Whipple’s disease include chronic joint pain, joint manifestations, persistent diarrhea, abdominal pain, excessive weight loss, tiredness, and fever. Over 90% of patients with WD experience weight loss, while more than 70% complain of either arthralgias or diarrhea. Caucasian men between the ages of 40 and 60 are more likely to develop this disease as opposed to any other group.

A diagnosis of Whipple’s disease can be determined after around 6 years due to the slow onset of joint symptoms. Moreover, diagnosis is often delayed due to the fact that WD is commonly misdiagnosed as another inflammatory disorder, such as rheumatoid arthritis (RA). A recently published study aimed to identify the symptoms of WD, why it is often mistaken for RA, and what is the appropriate treatment for the disease. Researchers analyzed 7 patients who were misdiagnosed with rheumatoid arthritis. The average age of the patients was 54 and the average time from the onset of their symptoms until diagnosis of Whipple’s disease was 5 years. During this time period, only 6 patients received immunosuppressive treatment, even though WD should be treated with antibiotics. “Without antibiotic treatment the natural course of WD may be fatal; erroneously induced immunosuppressive treatment may even accelerate the clinical progression of the disease” wrote the authors.

What leads to incorrect diagnosis?

Following diagnosis of Whipple’s disease, all 7 patients were started on antibiotic treatment for 12-20 months. The researchers determined that it was likely that the patients received a diagnosis of rheumatoid arthritis due to the fact that they suffered from joint manifestations mimicking symptoms of RA. Moreover, the disease affected the small joints in all of the patients, whereas in Whipple’s disease, the small joints are rarely affected. “The fact that bone erosions of the small joints are rather characteristic for RA and are part of the 1987 ACR-classification criteria for RA might have led to the wrong diagnosis in the reported patients” wrote the authors.

During this time, the authors recommended re-assessing seronegative RA patients with prolonged course of the disease and unsatisfactory response to treatment because thorough diagnosis of Whipple’s disease requires testing of TW-polymerase chain reaction to synovial fluid. TW-polymerase chain reaction is sensitive test that magnifies the DNA of the T. whipplei bacteria from tissue samples. “It is possible that destructive arthritis is misinterpreted even by radiologists and that a wrong interpretation of radiographs may lead to the wrong diagnoses. Thus, both rheumatologists and radiologists should increase their awareness for rare diseases like WD as a reason for erosive bone changes,” noted the authors.