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Original Report |
1
Department of Radiology, University Hospital Antwerp, Wilrijkstraat 10, B-2650
Edegem, Belgium.
2
Department of Radiology, St.-Jan Ziekenhuis Z.O.L., Schiepse Bos 6, B-3600
Genk, Belgium.
3
Department of Gastroenterology, University Hospital Antwerp, B-2650 Edegem,
Belgium.
4
Department of Immunology, Allergology and Rheumatology, University Hospital
Antwerp, B-2650 Edegem, Belgium.
Received March 13, 2000;
accepted after revision July 6, 2000.
Address correspondence to A. I. De Backer.
Abstract
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CONCLUSION. Thickening of the small-bowel wall and mucosa with increased contrast enhancement, depiction of more layers of the small-bowel wall than normal, prominent mesenteric vessels, ascites, and fluid accumulation in the small bowel or together in the small bowel and the colon were the most significant CT findings in three patients with visceral angioedema. Findings appear to be transient.
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Clinical Findings
Clinical findings consisted of abdominal pain and distention (n =
3), nausea and vomiting (n = 2), and diarrhea (n = 2).
Patient 2 had recurrent complaints for many years, with symptoms lasting 1-2
days and sometimes accompanied by cutaneous swelling, wheezing, or dyspnea. In
patient 3, symptoms were followed by severe hypovolemic shock. Physical
examination showed diffuse abdominal tenderness without (n = 2) or
with (n = 1) rebound, hypoactive bowel sounds (n = 2),
severe hypotension (n = 1), and cutaneous swelling (n =
1).
Because of rebound tenderness, patient 1 underwent an exploratory laparotomy for suspected acute abdomen. Edematous bowel wall with patchy reddish discoloration and serous fluid in the peritoneal cavity were seen. No definite reason for the acute abdominal complaints was found.
Laboratory Analyses
Laboratory analyses in patient 1 showed C-reactive protein was 3.5 mg/dL
(0.1-1.0) and WBC count was 9500/mm3. Additional serum complement
studies obtained 1 day later showed C1q value of 0.15 g/L (normal range,
0.1-0.3 g/L), C3c value of 0.79 g/L (normal range, 0.75-1.40 g/L), and C4
value of 0.2 g/L (normal range, 0.1-0.4 g/L).
Blood analysis in patient 2 showed leukocytosis (WBC count of 11,000/mm3) with normal differentiation, C1-esterase inhibitor of 12 mg/dL (normal range, 25-41 mg/dL), C4 of 8 mg/dL (normal range, 14-56 mg/dL), and C1-esterase inhibitor functional activity of less than 15% (normal range, 69-127%).
Laboratory data in patient 3 were as follows: hemoglobin, 16.5 g/dL (normal range, 14-18 g/dL); hematocrit, 55% (normal range, 40-54%); WBC count, 9900/mm3 (normal range, 4400-10,000/mm3); C1-esterase inhibitor, 21 mg/dL (normal range, 25-41 mg/dL); C4, 15 mg/dL (normal range, 14-56 mg/dL); and C1-esterase inhibitor functional activity, 115% (normal range, 69-127%).
Imaging Findings
CT findings consisted of thickening of the small-bowel wall and mucosa with
increased contrast enhancement, depiction of more layers of the small-bowel
wall than normal, prominent mesenteric vessels, and ascites in all three
patients (Figs.
1A,1B
and 2). Fluid accumulation
within dilated small-bowel loops was seen in two patients who underwent CT
without administration of oral contrast medium; fluid accumulation in the
colon was noted in one of these patients
(Fig. 3A).
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Repeated CT of the abdomen was performed in two patients 4 and 9 days later, respectively, and showed a normal appearance of the small bowel without ascites (Fig. 3B).
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Acquired C1-esterase inhibitor deficiency often appears as a paraneoplastic syndrome associated with a variety of lymphoproliferative and other neoplastic and autoimmune disorders [9]. It is most commonly associated with lymphoma, multiple myeloma, Waldenström's macroglobulinemia, and chronic lymphocytic leukemia. Laboratory test results in patients with acquired C1-esterase inhibitor deficiency show low levels of C4 and C1 inhibitor during an acute attack [9, 10]. A low level of C1, which is seen in the acquired form of angioedema, is helpful in differentiating between acquired and hereditary variants [6]. Patients with acquired angioedema lack a family history and may have symptoms for many years before the diagnosis of an underlying malignancy [9, 10].
Angiotensin-converting enzyme inhibitors are drugs used to treat hypertension and congestive heart failure. Angioedema has been reported to be a rare side effect of angiotensin-converting enzyme inhibitors. The mechanism has been proposed to be a biochemical reaction related to the kallikrein-kinin system [2]. Angiotensin-converting enzyme (which is identical to kininase II) releases the carboxy terminal dipeptide Phe—Arg (phenylalanine-arginine) and inactivates the monopeptide bradykinin, which is a highly potent activator of the L-arginine nitric oxide system; the L-arginine nitric oxide system causes vasodilatation and increases vascular permeability. The angiotensin-converting enzyme inhibitor increases the concentration of bradykinin. Angioedema associated with angiotensinconverting enzyme inhibitors occurs with a frequency of 0.1-0.2% and has an onset of less than 7 days after initiation of treatment, although more chronic forms may be possible [11, 12]. The frequency, duration, and severity of attacks vary, but most cases are mild and resolve within 24-48 hr after discontinuation of the drug. A temporal relation between the initiation of medication and angioedema should be valuable as a diagnostic criterion [2, 12]. In cases of angioedema induced by angiotensin-converting enzyme inhibitor, the levels of C1 and C4 are not altered and the C1-esterase inhibitor functional activity is normal. Facial and peripheral angioedema are well-known idiosyncratic reactions to ionic contrast medium. On the contrary, angioedema of the small bowel has been reported in only one anecdotal case [5].
Gastrointestinal complaints may be the presenting feature in patients with angioedema, although the combination of gastrointestinal complaints with cutaneous or upper respiratory involvement is often seen [4, 5]. Abdominal pain may be the only symptom but is mostly associated with distention, nausea, and vomiting followed by watery diarrhea in the late course of the attack [1, 3, 10]. These symptoms are seldom life-threatening, are usually self-limiting, and are attributed to edema of the bowel wall and fluid accumulation into the intestinal lumen. Bowel necrosis, bowel perforation, or other related life-threatening complications have not, to our knowledge, been reported. Severe hypovolemic shock has been reported rarely and is thought to be a consequence of extensive fluid sequestration in the intestinal wall, intestinal lumen, and peritoneal cavity [1].
The nonspecific clinical presentation that is often seen and the variation in intensity of symptoms may lead to a significant delay in diagnosis or to unnecessary exploratory laparotomy for suspected acute abdomen [4]. Surgical exploration may show nondiagnostic findings including ascites and bowel edema. Although angioedema has no features that distinguish it from acute abdominal conditions requiring immediate surgical exploration, the absence of peritoneal signs, fever, or leukocytosis and the presence of bowel sounds may justify a more conservative treatment [10].
Gastrointestinal symptoms may pre-date the development of cutaneous or respiratory symptoms by many years in patients with the hereditary form of angioedema [4]. Because mortality in undiagnosed patients, mostly those with edema of the larynx, may occur, a detailed clinical history and a rigorous complement assessment are mandatory in these patients [3, 6].
Clinical diagnosis of angioedema of the gastrointestinal tract is seldom considered until repeated attacks occur. In some patients, however, findings on conventional radiographs of the abdomen and barium followthrough examination may suggest correct diagnosis. During acute attacks, multiple dilated small-bowel loops with regular thickened mucosal folds and a stacked-coin appearance, thumbprinting, and wall thickening may be seen [9, 10]. Airfluid levels may also be present. Both the small and large intestines may be involved, including jejunum, ileum, duodenum, and colon in descending frequency of involvement [9]. Findings appear to be segmental and transient with a return to normal after an attack.
Abdominal sonography and CT may depict bowel edema and the presence of ascites more reliably than conventional radiographs of the abdomen and barium follow-through. Intestinal wall edema and mesenteric edema result in thickening of the small-bowel wall and mucosa with increased contrast enhancement and prominent mesenteric vessels. CT often shows a striking contrast between the edematous submucosa of low attenuation separating the outer muscular layers and serosa from brightly enhancing thickened mucosa. Fluid distention of the small bowel is a constant finding during acute attacks, whereas fluid accumulation in the colon may often be present regardless of the severity of the attack.
When clinical or radiologic findings are suggestive of angioedema, serum levels of C4 and C1-esterase inhibitor and C1-esterase inhibitor functional activity complement levels must be measured and a the patient's medical history must be reviewed carefully for the use of angiotensin-converting enzyme inhibitors. When a significant elevation in the WBC count, a fever, chills, or peritoneal signs are present, further investigation should be performed promptly to exclude other causes.
The differential diagnosis based on the radiographic findings includes ischemia, shock bowel, Henoch-Schönlein purpura (vasculitis), intramural bleeding from trauma, anticoagulation therapy, hemophilia, nephrotic syndrome, infections, and inflammatory bowel disease [10, 11]. In patients with angioedema, the radiographic findings are entirely reversible, appear to be segmental, and are seen only during an acute episode. The correct diagnosis allows unnecessary surgical exploration or testing to be avoided and consequently leads to an effective therapy. In patients with acquired angioedema, a paraneoplastic syndrome should be ruled out.
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