Discussion of the case
The middle-aged male patient had a 6-month history of symmetric arthritis (predominantly involving the lower limb), inflammatory back pain, episodes of recurrent diarrhea, and one previous hospital admission for diarrhea, which led to reactive arthritis. He had other systemic features like fever and vague abdominal discomfort. His inflammatory parameters were significantly elevated, though the rheumatoid factor and ANA were negative. Chest X-ray was normal and pelvis AP view indicated bilateral sacroiliitis.
Differential diagnosis
Based on the aforementioned clinical features, the differential diagnoses to be considered are seronegative spondyloarthropathy and enteropathic arthritis – either reactive arthritis or inflammatory bowel disease-associated arthritis. If the diarrhea is due to other causes, the possibilities are ankylosing spondylitis and rheumatoid arthritis (uncommon presentation). Brucellosis could be a possibility, but recurrent diarrhea is not a characteristic symptom of the disease. Moreover, the high levels of ESR and CRP rule out the possibility of having any other metabolic diseases.
Discussion
The presence of predominant lower limb arthritis and inflammatory back ache are suggestive of seronegative spondyloarthropathy. However, an episode of diarrhea, around 6 months before the onset of first symptoms of arthritis, suggests reactive arthritis.
There are different diagnostic and classification criteria proposed for diagnosing reactive arthritis-like European Spondyloarthropathy Study Group criteria (ESSG) and the European Spondyloarthropathy Study Group preliminary criteria for the classification of spondyloarthropathy.1 Preliminary criterion proposed for the classification of Reiter's syndrome by Wilkens et al. (1981) is also useful as a diagnostic criterion.2 At the Third International Workshop on Reactive Arthritis (1996), a group of researchers proposed a set of non-validated criteria for research purposes.3 These criteria include the presence of typical peripheral arthritis (predominantly lower limb and asymmetric oligoarthritis) and evidence of preceding infection (clinical diarrhea or urethritis in the preceding 4 weeks; laboratory confirmation is essential if there is no clear evidence of infection). The tests to confirm the infections are not often performed in routine practice. Sieper et al. have suggested an algorithm for diagnostic confirmation, which is based on pre-test probability and clinical suspicion.4
Although the patient history suggests frequent diarrhea, the persistence of increased frequency of infection is unusual and should raise suspicion of an alternative diagnosis. This should include a possible inflammatory bowel disease, retroviral infection, or other infective conditions. Since HIV was negative, the other possible infection is brucellosis. The episodes of high-grade fever, lower limb arthritis, and inflammatory back pain suggest the possibility of brucellosis. Arthritis has been reported to be one of the only presentations of infection caused by brucellosis. Inflammatory back pain is the commonest musculoskeletal presentation reported in the Indian series. Fever with abdominal discomfort is another presentation. The current case had intermittent episodes of fever. However, diarrhea, one of the predominant presentations in the patient, is not commonly noted in brucellosis. But screening for brucellosis is worthwhile, since the reported incidence of brucellosis is 1.2% in the south Indian population, with 3% of the patients presenting with only musculoskeletal symptoms.5
Since the absence of occupational exposure and persisting diarrhea were contradicting the possibility of brucellosis, the patient was subjected to colonoscopy and biopsy. The colonoscopy and biopsy concluded it was a case of Crohn's disease.
Final diagnosis
Crohn's disease with arthritis
Take Home message
Ø Atypical presentation of reactive arthritis, including recurrent diarrhea should raise the suspicion of inflammatory bowel disease.
Ø Other possible infectious diseases should be considered while evaluating for inflammatory back ache.
References
- Dougados M, van der Linden S, Juhlin R, Huitfeldt B, Amor B, Calin A, et al. The European Spondylarthropathy Study Group preliminary criteria for the classification of spondylarthropathy. Arthritis Rheum. 1991 Oct;34(10):1218–27.
- Willkens RF, Arnett FC, Bitter T, Calin A, Fisher L, Ford DK, et al. Reiter's syndrome. Evaluation of preliminary criteria for definite disease. Arthritis Rheum. 1981 Jun;24(6):844–9.
- Sieper J, Braun J. Problems and advances in the diagnosis of reactive arthritis. J Rheumatol. 1999 Jun;26(6):1222–4.
- Sieper J, Rudwaleit M, Braun J, van der Heijde D. Diagnosing reactive arthritis: Role of clinical setting in the value of serologic and microbiologic assays. Arthritis & Rheumatism. 2002 Feb 1;46(2):319–27.
- Mantur BG, Amarnath SK, Shinde RS. Review of clinical and laboratory features of human brucellosis. Indian J Med Microbiol. 2007 Jul;25(3):188–202.
