To our knowledge, there are no reports on the relationship between chronic diarrhea and FMF. The present case suggests that FMF should be considered to be a cause of chronic diarrhea, especially when organic gastrointestinal diseases are excluded.
FMF is characterized by self-limiting fever episodes, usually accompanied by serositis, arthralgia, and arthritis . The diagnosis of FMF is made based on patient history, inflammatory markers, and genetic testing . Several clinical diagnostic criteria sets have been proposed for diagnosis of FMF. The Tel Hashomer criteria, Livneh criteria, and Turkish pediatric criteria all rely on clinical symptoms, family history, and colchicine response [7,8,9]. In the diagnosis of Japanese patients with FMF, modified Tel Hashmer criteria (Fig. 3) have been suggested . These include: recurrent febrile episodes (three or more episodes lasting 12 h to 3 days with fever ≥ 38 °C), and eight minor criteria as shown in Fig. 3. A diagnosis of FMF is determined if the patient exhibits the major criteria and one or more minor criteria. Differential diagnoses include infections, malignancy, and autoinflammatory diseases. In the present case, we diagnosed FMF because of recurrent febrile episodes and a favorable response to colchicine.
With regard to treatment for FMF, there are limited RCTs assessing interventions for patients with FMF in the most recent Cochrane Database . Based on the evidence, daily colchicine may reduce the number of attacks. It has also been described that canakinumab probably reduces the number of attacks, and anakinra or canakinumab probably reduce CRP in colchicine-resistant participants. Thus, further research should be carried out to establish standard therapy for FMF.
With regard to a relationship between FMF and gastrointestinal disorders, accumulating evidence has suggested that some FMF patients exhibit intestinal mucosal lesions resembling inflammatory bowel diseases (IBD) [11, 12]. Uslu et al.  demonstrated that disease-causing MEFV mutations and the FMF disease rate were increased among patients with IBD. This increase was prominent among CD patients. Thus, FMF is considered to be a possible cause in patients with chronic intestinal mucosal lesions. However, in the present case, upper and lower gastrointestinal endoscopy detected no mucosal lesions in the gastrointestinal tract. These findings suggested that chronic diarrhea and abdominal pain came from functional but not organic gastrointestinal diseases such as IBD. Ekinci et al. examined a relationship between FMF and functional gastrointestinal disorders . In their report on Turkish people, D-IBS was observed in 3 out of 103 FMF patients (2.9 %) and 2 out of 100 healthy subjects (2 %), respectively, suggesting that coexistence of FMF and D-IBS was not high in FMF when compared with healthy control. In other words, we suggest that D-IBS was observed incidentally in patients with FMF. In the present case, D-IBS developed from FMF rather than other causes incidentally because colchicine completely prevented not only typical FMF-induced febrile attacks but also severe diarrhea and abdominal pain.
The present case demonstrates that FMF can present IBS-like symptoms without intestinal mucosal lesions. In clinical practice, we do not usually rule in/out FMF when IBS is considered to be a highly possible diagnosis in patients with diarrhea and abdominal pain without any organic abnormality. FMF can be diagnosed even if mutation of MEFV gene is not detected. In Japan, MEFV gene mutation is not detected in approximately 5% of patients with FMF . The present case suggests that patients with FMF may manifest gastrointestinal disease mimicking IBS, because colchicine potently improved not only periodic fever but also gastrointestinal symptoms such as diarrhea and abdominal pain.
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