Small bowel infarction due to fibro muscular dysplasia: a case report and literature review

On reassessment of abdomen it was more tender with both guarding and rebound tenderness. She underwent laparotomy which showed complete infarction of small bowel, Gall bladder and spleen. Large bowel was infracted up to splenic flexure. Liver also appeared ischaemic. No procedure could be carried out and abdomen was closed. She subsequently died after around six hours in the post operative period. An autopsy was requested in view of operative findings. Post mortem examination confirmed the presence of organized thrombus at the origin of celiac and superior mesenteric arteries. In the aorta there was eccentric intimal thickening with loss of smooth muscle and a proliferation of elastic tissue [Figure 1]. The nature of the lesion was confirmed as intimal fibro muscular dysplasia and thrombosis causing stenosis and subsequent occlusion of the origin of superior mesenteric and celiac artery [Figure 2]. Intimal fibro muscular dysplasia of aorta causing stenosis of the origin of superior mesenteric and celiac artery was rare in medical literature.

FMD is an idiopathic non-atherosclerotic and non-inflammatory vascular disease that primarily affects medium and small size arteries. It is more commonly seen in female patients (M: F ratio 1:3.5) in the middle thirds of their lives [1]. It causes arterial lumen to become irregular, so thrombus formation and subsequent distal embolisation can occur. Most commonly involved sites include renal (63%-89%) and cerebral arteries (25%-38%). Less commonly affected sites are mesenteric (9%) (Table 1), subclavian (9%) and iliac (5%) arteries [2, 3]. Multi vessel disease occurs in 24%-28% of patients. Diagnosis of mesenteric FMD is challenging and it can closely mimic vasculitis and atherosclerosis. Only medial fibroplasia gives a characteristic string of beads appearance on angiogram, rest of the types may be indistinguishable from atherosclerosis [3]. Occurrence of FMD in variety of vessels is responsible for wide range of symptoms including hypertension (Renal), stroke (carotid), headache (cerebral), abdominal pain (mesenteric) and claudication (iliac/femoral) [3, 4]. Although a variety of genetic, mechanical and hormonal factors have been proposed, the cause of FMD remains unknown. Cigarette smoking and hypertension are associated with increased risk of this condition [5]. No association has been found between FMD and use of oral contraceptives or abnormalities of endogenous sex hormones [5]. Genetic factors may play a role in the development of FMD as the disease is more common in the first degree relatives of patients with FMD of renal arteries [6]. Rushton [7] presented evidence consistent with a pattern of automosomal dominant inheritance with variable penetrance. Since there is evidence of a genetic preponderance, first degree relatives of patients with FMD may be screened for detection of asymptomatic disease and early intervention[7]. Harrison and McCormack [8] in 1971 established criteria for the pathological classification of FMD. Three main categories of FMD are described, based on the involvement of the arterial layer: medial, intimal and periarterial or adventitial. Medial FMD can be further characterized in to medial fibroplasia, perimedial fibroplasia, and medial hyperplasia. Medial fibroplasia is most common (60-70%) and often affecting the distal two thirds of the main artery and its branches, giving an appearance of "strings of beads" on arteriogram. Perimedial fibroplasia occurs in 15-20% of cases and medial hyperplasia is less common and account for 5% to15% of cases. Symptoms of mesenteric arterial stenosis and/or occlusion include nausea, vomiting, abdominal pain, anorexia and weight loss regardless of the cause [9]. Leadbetter and burkland [9] first described FMD in the renal artery of a small child in 1938 and FMD was thought to be restricted to the renal and carotid arteries. Palubinskas and Ripley [10] first reported a case of caeliac and mesenteric arteries in 1964. Mettinger in 1982 reviewed the literature on FMD and there were only 14 cases involving mesenteric arteries, none involving celiac axis and one splenic artery. In symptomatic patients with mesenteric FMD, revascularisation is necessary but by the time symptoms of abdominal pain, weight loss, nausea and vomiting develops, the disease has progressed to a critical stage and surgery is poorly tolerated [11].

Author	Pathology	Treatment offered	Result
Yamaguchi et al(Am J Gastroenterol, 1996, 91(8):1635-8)	Stenosis of jejunal and sigmoid branch	Conservative treatment leading to stenosis	Favourable
Hamed et al.(J Ped Surg, 1997, 32(9):1379-80)	SMA Occlusion due to intimal Fibroplasia leading to intestinal gangrene	Exploratory Laparotomy	Unfavourable-Died
Mertens et al. (Acta chir belg, 2005, 105: 523-527)	Occlusion of SMA and celiac trunk leading to visceral ischaemia	Reimplantation of Superior Mesenteric Artery	Favourable-Well two years after surgery