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Case Report |
1
Department of Diagnostic Radiology, University of Ulsan College of Medicine,
Asan Medical Center, 388-1 Poongnap-dong, Songpa-gu, Seoul, 138-736,
Korea.
2
Department of Diagnostic Pathology, University of Ulsan College of Medicine,
Asan Medical Center, Seoul, 138-736, Korea.
3
Department of Gastroenterology, University of Ulsan College of Medicine, Asan
Medical Center, Seoul, 138-736, Korea.
Received September 2, 1999;
accepted after revision November 23, 1999.
Address correspondence to H. K. Ha.
Introduction
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On abdominal sonography on the 15th day after her admission, variable-sized, multiple, hypoechoic nodules were found in both lobes of the liver. Follow-up abdominal CT was then performed on the same day and showed that although the bowel wall thickening of the ileum had improved, bowel wall definition had been completely lost at multiple sites because of the absence of or poor contrast enhancement along with extraluminal fluid and air collections (Fig. 1B). Also noted were multiple low-density nodules (Fig. 1C) in the liver, which had not been seen on initial CT.
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Because of the suggestion of a hepatic abscess, she underwent sonographically guided needle biopsy of the liver nodules. The consistency of the mass was hard and no pus was aspirated. Because of the patient's symptoms and signs of diffuse peritonitis, the patient underwent emergent laparotomy before physicians received the results of the biopsy. On the surgical field, both the jejunum and ileum showed diffuse hemorrhagic and edematous bowel wall thickening; the intestine from the jejunum, 70 cm below the Treitz's ligament to the ileum 60 cm above the ileocecal valve, showed multisegmented areas of necrosis and hemorrhage with multiple sites of bowel perforation (Fig. 1D). Segmental resection of the necrotic small bowel with end-to-end anastomosis was performed.
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Microscopic examination of the resected bowel showed extensive fungal proliferation in the necrotic tissue and vascular spaces. The fungi had thick, nonseptated hyphae with right-angled branches; these findings are characteristic of infection with Mucoraceae. Microscopic examination of the hepatic nodules obtained from the sonographically guided biopsy specimen also showed characteristic hyphae with severe coagulative necrosis caused by thrombotic involvement of the hepatic vessels.
After surgery, IV amphotericin B was administered, after which the patient's symptoms improved considerably. However, liver dysfunction became progressively aggravated despite intensive medical treatment. The patient died of hepatic failure 4 months after surgery.
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In contrast to the involvement of other organs, the gastrointestinal variant usually complicates local disease processes, such as intractable peptic ulceration, amoebic colitis, persistent peritonitis, and malnutrition [1,2]. With few exceptions, gastrointestinal mucormycosis pursues a fulminant and rapidly fatal course [3], and survival is largely dependent on proper diagnosis accompanied by surgical resection of infected bowel with administration of IV amphotericin B.
Regardless of the involved sites, histologic examination of the lesions shows broad, irregularly shaped, and nonseptated hyphae with right-angle branching [1,2,3,4,5,6]. Fungi of the order Mucorales exhibit a remarkable tendency to infiltrate the walls of blood vessels, especially arteries. They grow profusely into the vessel lumen and initiate acute vasculitis and thrombosis of major blood vessels. As a result of such vascular thrombosis, ischemic infarction can occur in any organ [2,6]. In some instances, venous involvement with thrombosis causes hemorrhagic necrosis [4].
Limited reports in the literature describe the radiologic findings of mucormycosis involving the abdomen [6]. Contrast-enhanced CT studies of our patient showed diffuse circumferential wall thickening with areas of both intense and poor contrast enhancement, especially in the small intestine. Pathologic correlation of the resected bowel with CT showed that poorly enhanced areas coincided with the areas of necrosis and infarction with mucosal ulceration and perforation caused by fungal proliferation in the necrotic tissues and vascular spaces, whereas intensely enhanced areas represented the areas of edema and hemorrhage in the submucosa and muscle layers caused by congestive changes. Therefore, such CT findings might easily be confused with chemotherapy-induced necrotizing enteropathy if they were seen in patients with lymphoma or leukemia who had received chemotherapeutic regimens [7].
Another interesting feature of this patient was the presence of multiple, hypoattenuated nodules in the liver, simulating multiple hepatic abscesses or metastases. In other reports of hepatic mucormycosis [5,8], postmortem macroscopic and microscopic examinations of liver tissues revealed thrombus in the hepatic vessels, irregular areas of necrosis, and extensive ischemic necrosis of hepatocytes. In our patient, histologic study of the nodules revealed that hypoattenuation resulted from coagulative necrosis of the hepatic tissues caused by acute thrombotic occlusion of the hepatic vessels. Such findings may not be pathognomonic for mucormycosis. However, the absence of mass effect to the surrounding hepatic anatomic structures would be helpful in suggesting the possibility of abscess caused by angioinvasive organisms, such as Mucor, Aspergillus, Candida, Cryptococcus, Torulopsis, and Pseudomonas aeruginosa [6].
Finally, our experience suggests that mucormycosis and other opportunistic fungal infections should be considered in the differential diagnosis of what appears to be an inflammatory bowel process that occurs acutely in a patient with some form of immunosuppression, including cancers such as leukemia and lymphoma, diabetes, or even systemic lupus erythematosus.
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