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Clinically occult isolated right iliac mycotic aneurysm with duodenal involvement in a diabetic elderly man
Journal of Clinical Imaging 27 (2003) 129 – 131
Clinically occult isolated right iliac mycotic aneurysm with duodenal involvement in a diabetic elderly man Multislice CT diagnosis Sheung-Fat Koa,*, Fan-Yen Leeb, Shu-Hang Nga, Tze-Yu Leea, Yung-Liang Wana a
Department of Radiology, Chang Gung University, Chan Gung Memorial Hospital, 123, Ta-Pei Road, Niao-Sung Hsiang, Kaohsiung Hsien 833, Taiwan b Department of Cardiovascular Surgery, Chang Gung University, Chan Gung Memorial Hospital, Kaohsiung, Taiwan Received 25 January 2002; accepted 25 March 2002
Abstract A diabetic old man presented with vague abdominal discomfort and intermittent tarry stools for 2 days and gastric ulcers with bleeding was diagnosed after endoscopy. Multislice computed tomography (MSCT) clearly depicted an isolated right iliac mycotic aneurysm with retroperitoneal extension and duodenal involvement. Timely operation and effective antibiotic treatment resulted in complete recovery. To our knowledge, this is the first report of an isolated mycotic iliac artery aneurysm (IAA) complicated with an aneurysmo-duodenal fistula induced by Klebsiella pneumoniae. D 2003 Elsevier Science Inc. All rights reserved. Keywords: Mycotic aneurysm; Iliac artery; Arterioduodenal fistula; Multislice computed tomography; Klebsiella pneumoniae
1. Introduction
2. Case report
Iliac artery aneurysms (IAAs) are uncommon with a prevalence of 1 in 12,000 autopsies studied, most arising due to pre-existing atherosclerosis [1 – 3]. Mycotic aneurysms constitute only 0.06– 3.0% of all aneurysms [4,5] and isolated mycotic iliac artery aneurysms (IAA) are unusual [5]. Three cases of isolated iliac arterio-duodenal fistulae have been previously described and their preoperative diagnosis was difficult to make [3,6,7]. To our knowledge, only case of isolated mycotic IAA caused by Klebsiella pneumoniae in a diabetic patient has previously been described [8], and this is the first report of such mycotic IAA complicated with an aneurysmo-duodenal fistula. Recently, a four-channel multislice computed tomography (MSCT) scanner has been developed with marked improvement in performance as compared to conventional scanning technique [9,10]. This report highlights that MSCT is a promising noninvasive tool for elucidating clinically occult abdominal vascular lesions and their complications, thus, allowing for prompt and timely surgery where appropriate.
A 68-year-old male patient presented with vague abdominal pain and tarry stools for the preceding 2 days. He had a 10-year history of diabetes mellitus under regular treatment. Four months prior this admission, he received a right neck incision for drainage of a deep neck abscess, a culture from which yielded K. pneumoniae. Two months subsequently, a mild right leg edema arose although pelvic sonography and a Doppler study were negative. On admission, the patient’s physical examination revealed a body temperature of 36.5 °C, a heart rate 92 beats/min, a respiratory rate of 16/ min and a blood pressure of 95/60 mm Hg. Further, his right lower extremity appeared slightly edematous, but the arterial pulses of the bilateral lower extremities were normal. His abdomen was soft with no apparent tenderness or any palpable abdominal mass. Laboratory examinations were unremarkable apart from an elevated blood sugar level (234 mg%) and a mild anemia (hemoglobin 9.9 g% and a hematocrit of 29.3%). No leukocytosis was noted. An endoscopic examination revealed active gastric ulcers with recent bleeding and an abdominal sonogram demonstrated mild right hydronephrosis. Upper gastrointestinal bleeding was initially diagnosed and the patient was treated medially. Due to the patient’s persistent vague abdominal discomfort, CT
* Corresponding author. Fax: +886-7-7318762. E-mail address: [email protected] (S.-F. Ko).
0899-7071/03/$ – see front matter D 2003 Elsevier Science Inc. All rights reserved. PII: S 0 8 9 9 - 7 0 7 1 ( 0 2 ) 0 0 4 8 8 - 6
130
S.-F. Ko et al. / Journal of Clinical Imaging 27 (2003) 129–131
was used to assess the abdominal condition. A MSCT (Volume Zoom, Siemens, Forchheim, Germany) scanning unit was used and settings including a collimation of 4 1.5 mm, a pitch of 4.0, a half-second rotation time, 140 kV and 120 mAs. A 100-ml of contrast material (Optiray, 350 mg/ ml, Mallinckrodt Medical, Australia) was administered with an injection rate of 2 ml/s via the right antecubital vein with a scan delay of 40 s and a total scan time of 20 s. After the examination, the raw data were immediately reconstructed to 1.5-mm thickness and were subsequent postprocessed with multiplanar reconstructions. CT images showed an approximately 10 6-cm arterial out-pouching with a narrow neck arising at the junction of the right external and internal iliac arteries. Its surrounding inflammatory changes, retroperitoneal extension and duodenal involvement were also demonstrated, but there was no leakage of contrast medium to the bowel lumen (Fig. 1). No other aneurysm formation was found in the atherosclerotic abdominal aorta and the left iliac artery. A mycotic IAA involving the duodenum was impressed. During surgery, the surgeons found a 10-cm right iliac mycotic aneurysm invading the third portion of the duodenum resulted in an aneurysmo-duodenal fistula (1.5 cm in diameter) that was partially occluded by blood clots. Proximal ligation of the right common iliac, external and internal arteries, aneurysmectomy, femoro-fermoral bypass with 8-mm ringed GORE-TEX graft, debridement of the retroperitoneal inflammatory tissue and duodenorrhaphy were performed as a result of the collaboration of the vascular and general surgeons. A pathological examination revealed a mycotic aneurysm with an aneurysmo-duodenal fistula. Necrosis of the anuerysmal wall with areas of fibrous tissue and focal aggregations of bacterial clumps were also noted. Both a blood culture and culture from the resected anuerysmal wall proved positive for K. pneumoniae. The patient recovered uneventfully subsequent to antibiotic treatment and his right lower extremity edema resolved. He was discharged 2 weeks later and he was well at a 5-month follow-up medical examination.
3. Discussion
Fig. 1. (A) Axial MSCT scan showing a large right iliac mycotic aneurysm displacing the inferior vena cava (white arrow). The neck of the aneurysm (black arrowhead), the periaortic inflammatory masses (white arrowheads) and infiltrations in the adjacent fat are clearly shown. (B) Coronal oblique multiplanar reconstruction view demonstrating the retroperitoneal extension of the right iliac mycotic aneurysm (black arrows) involving the duodenal loop (D). Note the lateral bulging of the inferior vena cava (white arrows) while the abdominal aorta and left iliac artery are not affected.
Most IAAs appear to lack apparent symptoms and, when such a condition does become symptomatic, associated mass and erosion effects upon adjacent structures may elicit renal colic, hematuria, sciatic nerve root pain, hematuria, hematochezia or vascular symptoms [1– 3]. Predisposing factors of mycotic aneurysm include bacterial endocarditis, intravenous drug abuse, immunocompromise, alcoholism, prior arterial trauma due to catheterization or surgery, vertebral osteomyelitis or abscess elsewhere, existing arterial graft and diabetes mellitus [4,5]. The most common infecting organisms are Salmonella species, Staphylococcus aureus and Streptococcus pneumoniae. An isolated mycotic IAA caused by K. pneumoniae is exceedingly rare and only one such case in a diabetic patient has previously been described
S.-F. Ko et al. / Journal of Clinical Imaging 27 (2003) 129–131
[8]. Occasionally, IAA may be complicated by an arterioenteric fistula that is often present with severe abdominal pain and catastrophic intestinal hemorrhage [1 –5]. In retrospect, for this patient, the only early clue to his condition was the leg edema, which arose due to compression on the right iliac vein. The presence of tarry stools and the endoscopic findings of gastric ulcers, as well as an absence of any massive bleeding and a lack of any palpable abdominal mass, were indeed misleading. Since the causative organism of the neck abscess and the mycotic aneurysm was the same, it is plausible that the bacteria in the neck abscess disseminated hematogenously and was subsequently entrapped in the atherosclerotic plaque at the bifurcation of the internal and external iliac arteries, leading to the formation of the mycotic aneurysm. Despite fistulization of the duodenum and positive cultures for K. pneumoniae, there were no inflammatory symptoms and signs such as fever and/or leukocytosis, probably ascribed to the relatively poor immunity status of this diabetic old man. Because mycotic aneurysm is unusually suspected clinically under such a diagnostic scenario, imaging studies play an important role in the detection of this disease [4,5]. However, only 35% of IAA can be detected on the plain radiograph [1]. The mid-portion of iliac arteries is often obscured by overlying gas-filled bowels on sonogram. Angiography is invasive and, in practical term, it is not ideally suitable for screening purposes. Magnetic resonance imaging can demonstrate aortoiliac lesions but it is a timeconsuming study and is not always available on a 24-h emergency basis. CT may be an effective noninvasive method in revealing clinically subtle mycotic aneurysms [4,5]. Early CT findings of include periaortic mass and an increased fat density around the lesion, while for the advanced disease, a rapidly enlarging saccular aneurysm, disrupted calcified aortic wall, paraaortic gas, enlarged lymph nodes or retroperitoneal hematoma may be found alone or in combination [4,5]. Noteworthily, as in our case, enteric fistulization complicated by mycotic aneurysm may not be demonstrated all the time, because contrast medium leakage to the bowel may be intermittent or the fistula may temporarily be occluded by clots [3]. Recently, MSCT with data collection through multiple interleaving helices and a subsecond gantry rotation represents a quantum leap in helical CT development that offer an eight-fold increase in performance when compared to the conventional CT instru-
131
ment [8]. Increased volume coverage, improved z-axis resolution, better image quality and reduced image noise and artifact further facilitate the application of MSCT in poorly cooperative and/or emergency patients [9,10]. MSCT allows complete evaluation of the entire abdomen and pelvis within 15– 20 s. In addition, immediate multiplanar and three-dimensional reconstructions of raw data can provide vascular images comparable to arteriograms [4,9,10], and the whole procedure can be completed within 2 min. As seen in our case, MSCT allowed direct visualization of IAA, its pathoanatomic relationships to the adjacent and distal structures and associated perivascular changes. In summary, this report documented an unusual case of mycotic IAA caused by K. pneumoniae with retroperitoneal extension forming a clinically unexpected ilioduodenal fistula in a diabetic old man. MSCT appears to be a rapid, effective noninvasive tool for the delineation of abdominal or pelvic vascular diseases and their potential complications.
References [1] Sacks NPM, Huddy SPJ, Wegner T, Giddings AEB. Management of solitary iliac aneurysms. J Cardiovasc Surg 1992;33:679 – 83. [2] Lowry SF, Kraft RO. Isolated aneurysms of the iliac artery. Arch Surg 1978;113:1289 – 93. [3] Nicolaou DD, Mysko WK. Enteric fistulization of a common iliac artery aneurysm: an unusual cause of gastrointestinal hemorrhage and shock. Am J Emerg Med 1996;14:272 – 5. [4] Sueyoshi E, Sakamoto I, Kawahara Y, Matsuoka Y, Hayashi K. Infected abdominal aortic aneurysm: early CT findings. Abdom Imaging 1998;23:645 – 8. [5] Alarco´n M, Quiroga S, Sebastia´ MC, Pe´rez M, Pallisa E, AlvarezCastells A. Arteriovenous fistula secondary to iliac mycotic aneurysm: helical CT findings. Abdom Imaging 2000;25:55 – 8. [6] Grosfeld JL, Eng K. Right iliac artery-duodenal fistula in infancy: massive hemorrhage due to ‘‘whisk-broom’’ bristle perforation. Ann Surg 1972;176:761 – 4. [7] Abraumson PD, Jameson JB. Rupture of iliac aneurysm into duodenum: an unusual cause of gastrointestinal hemorrhage. Arch Surg 1955;71:658 – 61. [8] Tatebe S, Kanazawa H, Yamazaki Y. Mycotic aneurysm of the internal iliac artery caused by Klebsiella pneumoniae. Vasa 1996; 25:184 – 7. [9] Klingenbeck-Regn K, Schaller S, Flohr T, Ohnesorge B, Kopp AF, Baum U. Subsecond multi-slice computed tomography: basic and applications. Eur J Radiol 1999;31:110 – 24. [10] Hui H, Pan T, Shen Y. Multislice helical CT: image temporal resolution. IEEE Eng Med Biol Mag 2000;19:384 – 90.
Clinically occult isolated right iliac mycotic aneurysm with duodenal involvement in a diabetic elderly man Multislice CT diagnosis Sheung-Fat Koa,*, Fan-Yen Leeb, Shu-Hang Nga, Tze-Yu Leea, Yung-Liang Wana a
Department of Radiology, Chang Gung University, Chan Gung Memorial Hospital, 123, Ta-Pei Road, Niao-Sung Hsiang, Kaohsiung Hsien 833, Taiwan b Department of Cardiovascular Surgery, Chang Gung University, Chan Gung Memorial Hospital, Kaohsiung, Taiwan Received 25 January 2002; accepted 25 March 2002
Abstract A diabetic old man presented with vague abdominal discomfort and intermittent tarry stools for 2 days and gastric ulcers with bleeding was diagnosed after endoscopy. Multislice computed tomography (MSCT) clearly depicted an isolated right iliac mycotic aneurysm with retroperitoneal extension and duodenal involvement. Timely operation and effective antibiotic treatment resulted in complete recovery. To our knowledge, this is the first report of an isolated mycotic iliac artery aneurysm (IAA) complicated with an aneurysmo-duodenal fistula induced by Klebsiella pneumoniae. D 2003 Elsevier Science Inc. All rights reserved. Keywords: Mycotic aneurysm; Iliac artery; Arterioduodenal fistula; Multislice computed tomography; Klebsiella pneumoniae
1. Introduction
2. Case report
Iliac artery aneurysms (IAAs) are uncommon with a prevalence of 1 in 12,000 autopsies studied, most arising due to pre-existing atherosclerosis [1 – 3]. Mycotic aneurysms constitute only 0.06– 3.0% of all aneurysms [4,5] and isolated mycotic iliac artery aneurysms (IAA) are unusual [5]. Three cases of isolated iliac arterio-duodenal fistulae have been previously described and their preoperative diagnosis was difficult to make [3,6,7]. To our knowledge, only case of isolated mycotic IAA caused by Klebsiella pneumoniae in a diabetic patient has previously been described [8], and this is the first report of such mycotic IAA complicated with an aneurysmo-duodenal fistula. Recently, a four-channel multislice computed tomography (MSCT) scanner has been developed with marked improvement in performance as compared to conventional scanning technique [9,10]. This report highlights that MSCT is a promising noninvasive tool for elucidating clinically occult abdominal vascular lesions and their complications, thus, allowing for prompt and timely surgery where appropriate.
A 68-year-old male patient presented with vague abdominal pain and tarry stools for the preceding 2 days. He had a 10-year history of diabetes mellitus under regular treatment. Four months prior this admission, he received a right neck incision for drainage of a deep neck abscess, a culture from which yielded K. pneumoniae. Two months subsequently, a mild right leg edema arose although pelvic sonography and a Doppler study were negative. On admission, the patient’s physical examination revealed a body temperature of 36.5 °C, a heart rate 92 beats/min, a respiratory rate of 16/ min and a blood pressure of 95/60 mm Hg. Further, his right lower extremity appeared slightly edematous, but the arterial pulses of the bilateral lower extremities were normal. His abdomen was soft with no apparent tenderness or any palpable abdominal mass. Laboratory examinations were unremarkable apart from an elevated blood sugar level (234 mg%) and a mild anemia (hemoglobin 9.9 g% and a hematocrit of 29.3%). No leukocytosis was noted. An endoscopic examination revealed active gastric ulcers with recent bleeding and an abdominal sonogram demonstrated mild right hydronephrosis. Upper gastrointestinal bleeding was initially diagnosed and the patient was treated medially. Due to the patient’s persistent vague abdominal discomfort, CT
* Corresponding author. Fax: +886-7-7318762. E-mail address: [email protected] (S.-F. Ko).
0899-7071/03/$ – see front matter D 2003 Elsevier Science Inc. All rights reserved. PII: S 0 8 9 9 - 7 0 7 1 ( 0 2 ) 0 0 4 8 8 - 6
130
S.-F. Ko et al. / Journal of Clinical Imaging 27 (2003) 129–131
was used to assess the abdominal condition. A MSCT (Volume Zoom, Siemens, Forchheim, Germany) scanning unit was used and settings including a collimation of 4 1.5 mm, a pitch of 4.0, a half-second rotation time, 140 kV and 120 mAs. A 100-ml of contrast material (Optiray, 350 mg/ ml, Mallinckrodt Medical, Australia) was administered with an injection rate of 2 ml/s via the right antecubital vein with a scan delay of 40 s and a total scan time of 20 s. After the examination, the raw data were immediately reconstructed to 1.5-mm thickness and were subsequent postprocessed with multiplanar reconstructions. CT images showed an approximately 10 6-cm arterial out-pouching with a narrow neck arising at the junction of the right external and internal iliac arteries. Its surrounding inflammatory changes, retroperitoneal extension and duodenal involvement were also demonstrated, but there was no leakage of contrast medium to the bowel lumen (Fig. 1). No other aneurysm formation was found in the atherosclerotic abdominal aorta and the left iliac artery. A mycotic IAA involving the duodenum was impressed. During surgery, the surgeons found a 10-cm right iliac mycotic aneurysm invading the third portion of the duodenum resulted in an aneurysmo-duodenal fistula (1.5 cm in diameter) that was partially occluded by blood clots. Proximal ligation of the right common iliac, external and internal arteries, aneurysmectomy, femoro-fermoral bypass with 8-mm ringed GORE-TEX graft, debridement of the retroperitoneal inflammatory tissue and duodenorrhaphy were performed as a result of the collaboration of the vascular and general surgeons. A pathological examination revealed a mycotic aneurysm with an aneurysmo-duodenal fistula. Necrosis of the anuerysmal wall with areas of fibrous tissue and focal aggregations of bacterial clumps were also noted. Both a blood culture and culture from the resected anuerysmal wall proved positive for K. pneumoniae. The patient recovered uneventfully subsequent to antibiotic treatment and his right lower extremity edema resolved. He was discharged 2 weeks later and he was well at a 5-month follow-up medical examination.
3. Discussion
Fig. 1. (A) Axial MSCT scan showing a large right iliac mycotic aneurysm displacing the inferior vena cava (white arrow). The neck of the aneurysm (black arrowhead), the periaortic inflammatory masses (white arrowheads) and infiltrations in the adjacent fat are clearly shown. (B) Coronal oblique multiplanar reconstruction view demonstrating the retroperitoneal extension of the right iliac mycotic aneurysm (black arrows) involving the duodenal loop (D). Note the lateral bulging of the inferior vena cava (white arrows) while the abdominal aorta and left iliac artery are not affected.
Most IAAs appear to lack apparent symptoms and, when such a condition does become symptomatic, associated mass and erosion effects upon adjacent structures may elicit renal colic, hematuria, sciatic nerve root pain, hematuria, hematochezia or vascular symptoms [1– 3]. Predisposing factors of mycotic aneurysm include bacterial endocarditis, intravenous drug abuse, immunocompromise, alcoholism, prior arterial trauma due to catheterization or surgery, vertebral osteomyelitis or abscess elsewhere, existing arterial graft and diabetes mellitus [4,5]. The most common infecting organisms are Salmonella species, Staphylococcus aureus and Streptococcus pneumoniae. An isolated mycotic IAA caused by K. pneumoniae is exceedingly rare and only one such case in a diabetic patient has previously been described
S.-F. Ko et al. / Journal of Clinical Imaging 27 (2003) 129–131
[8]. Occasionally, IAA may be complicated by an arterioenteric fistula that is often present with severe abdominal pain and catastrophic intestinal hemorrhage [1 –5]. In retrospect, for this patient, the only early clue to his condition was the leg edema, which arose due to compression on the right iliac vein. The presence of tarry stools and the endoscopic findings of gastric ulcers, as well as an absence of any massive bleeding and a lack of any palpable abdominal mass, were indeed misleading. Since the causative organism of the neck abscess and the mycotic aneurysm was the same, it is plausible that the bacteria in the neck abscess disseminated hematogenously and was subsequently entrapped in the atherosclerotic plaque at the bifurcation of the internal and external iliac arteries, leading to the formation of the mycotic aneurysm. Despite fistulization of the duodenum and positive cultures for K. pneumoniae, there were no inflammatory symptoms and signs such as fever and/or leukocytosis, probably ascribed to the relatively poor immunity status of this diabetic old man. Because mycotic aneurysm is unusually suspected clinically under such a diagnostic scenario, imaging studies play an important role in the detection of this disease [4,5]. However, only 35% of IAA can be detected on the plain radiograph [1]. The mid-portion of iliac arteries is often obscured by overlying gas-filled bowels on sonogram. Angiography is invasive and, in practical term, it is not ideally suitable for screening purposes. Magnetic resonance imaging can demonstrate aortoiliac lesions but it is a timeconsuming study and is not always available on a 24-h emergency basis. CT may be an effective noninvasive method in revealing clinically subtle mycotic aneurysms [4,5]. Early CT findings of include periaortic mass and an increased fat density around the lesion, while for the advanced disease, a rapidly enlarging saccular aneurysm, disrupted calcified aortic wall, paraaortic gas, enlarged lymph nodes or retroperitoneal hematoma may be found alone or in combination [4,5]. Noteworthily, as in our case, enteric fistulization complicated by mycotic aneurysm may not be demonstrated all the time, because contrast medium leakage to the bowel may be intermittent or the fistula may temporarily be occluded by clots [3]. Recently, MSCT with data collection through multiple interleaving helices and a subsecond gantry rotation represents a quantum leap in helical CT development that offer an eight-fold increase in performance when compared to the conventional CT instru-
131
ment [8]. Increased volume coverage, improved z-axis resolution, better image quality and reduced image noise and artifact further facilitate the application of MSCT in poorly cooperative and/or emergency patients [9,10]. MSCT allows complete evaluation of the entire abdomen and pelvis within 15– 20 s. In addition, immediate multiplanar and three-dimensional reconstructions of raw data can provide vascular images comparable to arteriograms [4,9,10], and the whole procedure can be completed within 2 min. As seen in our case, MSCT allowed direct visualization of IAA, its pathoanatomic relationships to the adjacent and distal structures and associated perivascular changes. In summary, this report documented an unusual case of mycotic IAA caused by K. pneumoniae with retroperitoneal extension forming a clinically unexpected ilioduodenal fistula in a diabetic old man. MSCT appears to be a rapid, effective noninvasive tool for the delineation of abdominal or pelvic vascular diseases and their potential complications.
References [1] Sacks NPM, Huddy SPJ, Wegner T, Giddings AEB. Management of solitary iliac aneurysms. J Cardiovasc Surg 1992;33:679 – 83. [2] Lowry SF, Kraft RO. Isolated aneurysms of the iliac artery. Arch Surg 1978;113:1289 – 93. [3] Nicolaou DD, Mysko WK. Enteric fistulization of a common iliac artery aneurysm: an unusual cause of gastrointestinal hemorrhage and shock. Am J Emerg Med 1996;14:272 – 5. [4] Sueyoshi E, Sakamoto I, Kawahara Y, Matsuoka Y, Hayashi K. Infected abdominal aortic aneurysm: early CT findings. Abdom Imaging 1998;23:645 – 8. [5] Alarco´n M, Quiroga S, Sebastia´ MC, Pe´rez M, Pallisa E, AlvarezCastells A. Arteriovenous fistula secondary to iliac mycotic aneurysm: helical CT findings. Abdom Imaging 2000;25:55 – 8. [6] Grosfeld JL, Eng K. Right iliac artery-duodenal fistula in infancy: massive hemorrhage due to ‘‘whisk-broom’’ bristle perforation. Ann Surg 1972;176:761 – 4. [7] Abraumson PD, Jameson JB. Rupture of iliac aneurysm into duodenum: an unusual cause of gastrointestinal hemorrhage. Arch Surg 1955;71:658 – 61. [8] Tatebe S, Kanazawa H, Yamazaki Y. Mycotic aneurysm of the internal iliac artery caused by Klebsiella pneumoniae. Vasa 1996; 25:184 – 7. [9] Klingenbeck-Regn K, Schaller S, Flohr T, Ohnesorge B, Kopp AF, Baum U. Subsecond multi-slice computed tomography: basic and applications. Eur J Radiol 1999;31:110 – 24. [10] Hui H, Pan T, Shen Y. Multislice helical CT: image temporal resolution. IEEE Eng Med Biol Mag 2000;19:384 – 90.