British Journal of Radiology (2003) 76, 22-25
© 2003 British Institute of Radiology
doi:
CT findings in patients with familial Mediterranean fever during an acute abdominal attack
R Zissin, MD
1
V Rathaus, MD
1
G Gayer, MD
2
M Shapiro-Feinberg, MD
1 and
M Hertz, MD
2
1 Department of Diagnostic Imaging, Sapir Medical Center, Kfar Saba 44281 and 2 Department of Diagnostic Imaging, Chaim Sheba Medical Center, Tel Hashomer, Tel Aviv, affiliated to the Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
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Abstract
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The aim of this study is to present the abdominal CT findings of patients with familial Mediterranean fever (FMF) examined during an acute abdominal attack. CT scans of 17 patients (10 women and 7 men; age range 11–45 years) were retrospectively reviewed. Attention was directed to mesenteric or peritoneal abnormalities and to the presence of appendiceal pathology. Patients were divided into two groups; group A (n=14) consisted of patients with an acute abdominal attack caused by FMF, and group B (n=3) consisted of patients whose attack proved to be owing to a separate pathology requiring surgery. Characteristic CT findings of acute abdomen in FMF included mesenteric pathology (n=12), mainly of engorged vessels with thickened mesenteric folds, mesenteric lymphadenopathy (n=6) and ascites (n=6). Signs of focal peritonitis were found in four patients. Radiologists should be familiar with such CT findings of peritoneal irritation in patients with FMF during an acute attack, and may suggest this clinical diagnosis in the proper clinical setting in a patient who has not been previously diagnosed. Alternatively, the radiologist should be aware of the possibility of a concurrent acute appendicitis or other acute abdominal pathology in patients with known FMF and should search for it.
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Introduction
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Familial Mediterranean fever (FMF) is an autosomal, recessively inherited disease resulting from a mutation in the gene for FMF [1]. The disease occurs in ethnic groups originating in the Mediterranean area, mainly in Sephardi Jews, Arabs, Turks and Armenians. Globalization in recent years has led to a rise of cross-border migration in Europe and the United States, which has led to a steady increase of the foreign population in many countries and FMF can therefore be encountered in many countries away from the Mediterranean.
The diagnosis of FMF is usually clinical since there are no specific imaging or laboratory tests, other than a molecular genetic test that is not widely available. The clinical picture is characterized by repeated, self-limited episodes of fever and inflammation of synovial and serous surfaces, mainly of the peritoneum and joints [1–3]. In 90% of cases the first attack occurs before 20 years of age. Patients usually experience no symptoms in between attacks. An acute abdominal attack usually presents with severe, diffuse abdominal pain and rigidity, and fever, a clinical setting commonly defined as an "acute abdomen". Physicians not familiar with the disease, or who have relatively little experience, may find it difficult to differentiate an attack of FMF from other acute abdominal conditions necessitating intervention, such as acute appendicitis and small bowel obstruction. In these circumstances imaging studies are useful for prompt and accurate diagnosis.
Nowadays, abdominal CT has evolved an important imaging technique for evaluating patients with acute abdomen. It is a rapid, cost effective examination with a high positive predictive value for pre-operative diagnosis in these patients [4–6]. As there are only a few reports on the CT findings in patients with known FMF examined during a typical abdominal crisis [7, 8], we present the CT findings in 17 such patients.
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Material and methods
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The clinical data and imaging studies of 17 patients with known FMF who had been admitted to our medical center with an acute abdominal attack, and had undergone an abdominal CT for diagnosis, were retrospectively reviewed. These patients underwent CT when the clinical picture was thought by the patient to be different from the usual presentation, or the physician in charge was not certain of the diagnosis.
These patients were examined over a period of 22 months (from September 1999 to June 2001). In this period a further 28 patients with FMF were referred with acute abdominal attack. The latter did not undergo CT as their symptoms were thought to be typical of FMF. All 45 patients had been diagnosed as suffering from FMF based on criteria set out in the literature [1].
The study population (n=17) included 7 men and 10 women with ages ranging from 11 years to 45 years (mean age 30.6 years). Six patients had previously undergone appendectomy. All patients presented with abdominal pain, accompanied by fever in 14 patients. Abdominal pain was diffuse in nine patients, located in the right lower quadrant (RLQ) in four, in the epigastrium in two and in the flank in one and in the periumbilical area in one.
Laboratory findings revealed leukocytosis in 14 patients ranging from 11 500 mm-3 to 23 000 mm-3.
CT scans were obtained on an Elscint 2400 Elite (non-helical) scanner (Philips Shefayem, Israel) or a Picker Mx Twin-flash (helical) scanner (Philips Shefayem, Israel) with 8.8–10 mm collimation and 0.8–1.0 cm interval from the diaphragm to the symphysis pubis. All patients received diluted, water soluble contrast material orally; 1000 ml administered over 2 h prior to examination and an additional 250 ml just before the study. 80–100 ml intravenous iodinated contrast medium (Iopromide) was given routinely. Injection was either manually by bolus (n=7) or with a power injector at a flow rate of 1.5 ml s-1 and a scanning delay of 70 s (n=10).
All CT studies were reviewed retrospectively, especially for the following findings:
- Abnormalities indicating peritoneal pathology, e.g. ascites, increased markings within the peritoneal fat and omental infiltration, or mesenteric abnormalities, e.g. engorgement of mesenteric vessels and thickened mesenteric leaves.
- Lymphadenopathy and/or splenomegaly.
- Appendiceal pathology.
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Results
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Patients were divided into two groups; group A included patients whose abdominal attack proved to be a typical FMF manifestation (n=14), and group B included patients who proved to have true acute abdomen and underwent surgery (n=3). Table 1
shows the abnormal abdominal CT findings in the 14 patients whose abdominal condition was related to FMF only (group A). On CT, mesenteric pathology was the most common finding, present in 12 of the 14 patients (85.7%), with congested mesenteric vessels as well as thick mesenteric leaves in 9 patients (Figures 1 and 2), engorged vessels only in two and thickened folds alone in one. Clustered (three or more) and enlarged (>5 mm in short axis) mesenteric lymph nodes were seen in 6 patients, in the interenteric mesenteric root in 4 (Figure 2a) and in the RLQ in 2. Additional enlarged nodes were present in the retroperitoneum in one patient (Figure 2a). Ascites was found in six patients (Figure 3). In four of these there were signs of focal peritonitis. These manifested as focal peritoneal thickening in the pelvis and increased markings within the mesenteric fat of higher attenuation than the uninvolved peritoneal fat in two patients (Figure 2b), and as slight omental infiltration (Figure 3) in the other two patients. Splenomegaly was demonstrated in three patients. Dilated small bowel loops were seen in two of these patients and a thick-walled ascending colon in the other. This may have been the result of the FMF attack, as a colonoscopy performed 6 weeks later in this patient was normal and healing had probably taken place. All 14 patients recovered following conservative therapy.
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Table 1. CT findings in 14 patients (group A) with familial Mediterranean fever during acute abdominal attack (Most patients had more than one finding)
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Figure 1. A 31-year-old man with known familial Mediterranean fever presented with abdominal pain, nausea and vomiting. Contrast-enhanced CT at the mid-abdomen shows engorged mesenteric vessels with a thickened mesenteric fold (white arrow).
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Figure 2. A 22-year-old man with known familial Mediterranean fever presented with fever, lower abdominal pain and tenderness. (a) Contrast enhanced CT scan at the upper abdominal level shows engorged mesenteric vessels and slightly enlarged mesenteric lymph nodes (small arrows). An enlarged retroperitoneal lymph node is also demonstrated. (b) Contrast enhanced CT a scan at the pelvic level shows slight infiltration of the intra-abdominal fat with higher attenuation than the uninvolved peritoneal fat (arrowheads), thickening of the parietal peritoneum anteriorly (arrow) and some mural thickening of the small bowel loop (small arrows), compatible with focal mild peritonitis.
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Figure 3. A 45-year-old woman with known familial Mediterranean fever presented with epigastric pain. Contrast enhanced CT shows omental infiltration (arrowhead), engorged mesenteric vessels and a small amount of ascites in both paracolic gutters.
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The three patients in group B proved to have true acute abdomen necessitating a definitive operative procedure; appendectomy in two patients and enterotomy with extraction of a foreign-body bezoar in the other. On CT, two patients had signs of acute appendicitis (Figure 4). Both also had splenomegaly and thickened mesenteric leaves. A small amount of ascites was also seen in one of these patients and enlarged mesenteric and retroperitoneal lymph nodes, as well as dilated small bowel loops, in the other. The third patient had dilated small bowel loops and a small amount of peritoneal fluid. On surgery a foreign body was found obstructing the jejunum. On questioning, the patient recalled having inadvertently swallowed the cap of a soda bottle one month earlier. He also stated that the abdominal pain was different from the pain experienced in previous FMF attacks. The post-operative course in these three patients was uneventful.
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Figure 4. A 21-year-old woman with known familial Mediterranean fever presented with low grade fever, right lower quadrant pain, nausea and diarrhoea. Contrast enhanced CT shows a slightly distended, fluid filled appendix in transverse section (arrowhead), compatible with acute appendicitis. At surgery this diagnosis was confirmed.
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Discussion
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FMF, also named recurrent polyserositis, is characterized by acute relapsing, most frequently abdominal attacks, that typically first appear at a young age. Such an acute episode has a sudden onset of pain associated with fever, and improves within 12–24 h as the attack runs its course [1–3]. Abdominal rigidity and pain with predilection of the RLQ and low-grade leukocytosis are often found [9]. The most important clinical point is therefore to differentiate an acute attack of FMF from coincidental surgical emergencies such as acute appendicitis. Adhesive small bowel obstruction (SBO), which has been reported with an incidence of up to 3% in the paediatric age group with FMF, is another life-threatening complication [10].
In the past, exploratory laparotomy and emergency appendectomy were often performed in patients with FMF during an acute attack who had a provisional diagnosis of acute appendicitis. A normal appendix was found in most of these cases [11]. Preventive elective appendectomy has even been suggested in patients with FMF [11] but has not ultimately been recommended by others [1].
Currently, abdominal CT has been reported to have high sensitivity, accuracy and specificity in diagnosing or ruling out acute appendicitis, and this imaging modality may replace exploratory emergency surgery [5]. Abdominal CT also plays an important role in establishing the diagnosis of small bowel obstruction and its severity [12, 13].
Three of the 17 patients (21%) with a known diagnosis of FMF in this study were found to have surgical emergencies on CT; two patients had findings of acute appendicitis and one had CT signs of a complicated SBO. In the other 14 patients, CT findings were compatible with mild peritonitis, excluding an acute surgical emergency and justifying conservative treatment.
The common CT features of mesenteric pathology found in this series and in two previous reports [7, 8] correlate with the macroscopic findings on laparoscopy or laparotomy during an acute attack. They include oedematous and hypaeremic peritoneal folds and greater omentum with vascular markings, interenteric exudates and fibrinonodular changes, while microscopic examination discloses a sterile non-specific inflammation [8, 9]. Such CT findings are, however, non-specific and appear in various diseases affecting the mesentery previously reported by Mindelzun et al [14] as the "misty mesentery", resulting from mesenteric infiltration by inflammatory cells, fluid, tumour and fibrosis.
Mesenteric lymphadenopathy was found in 6 and splenomegaly in 3 of the 14 patients with an acute abdominal attack of FMF discussed herein. Enlarged mesenteric lymph nodes have been reported in patients during an acute abdominal attack of FMF, either on laparotomy or on CT studies [7, 8]. Splenomegaly has been reported in 20% of patients with FMF [2].
In conclusion, CT signs of mesenteric and peritoneal irritation are common in a patient with known FMF during an acute abdominal attack. Radiologists should be familiar with this entity and may suggest the diagnosis of FMF when mesenteric pathology, a small amount of ascitic fluid, omental infiltration and splenomegaly are present on CT of a young patient with an appropriate ethnic background examined for an "acute abdomen". Alternatively, the radiologist should be alerted to the possibility of adhesive SBO or a coincidentally acute appendictis in patients with known FMF, and should search for it.
Received for publication June 17, 2002.
Revision received September 9, 2002.
Accepted for publication September 24, 2002.
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Abstract
Introduction
