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Q1: What is meant by the term “obscure gastrointestinal haemorrhage” and how would you investigate it?
In 5% of cases of gastrointestinal bleeding the cause cannot be identified by standard investigations; these would usually include a gastroscopy, colonoscopy and barium enema, and small bowel series. These unidentifiable bleeds are often referred to as obscure gastrointestinal bleeds.1
Small intestinal contrast radiology is abnormal in 60%–70% of small bowel tumours and diagnostic in 30%–40% of cases. Enteroclysis or intubated small bowel studies show more lesions than conventional barium follow through, probably because the more dilute barium solution allows smaller filling defects to be recognised.2 These should be performed before angiography, which itself may be diagnostic even in the absence of acute bleed by the presence of a tumour blush.
Small bowel enteroscopy is a new technique with increasing importance in potentially diagnosing and treating small bowel lesions. There are two types: push and sonde enteroscopy.3 Push enteroscopy entails peroral insertion of a long endoscope, and it allows for thorough examination of the distal duodenum and proximal jejunum. Sonde enteroscopy involves placement of a long, small calibre endoscope into the proximal small bowel: subsequent peristalsis carries the endoscope to the distal small intestine.4 Abdominal computed tomography is of little value in the primary diagnosis of small intestinal lesions as fluid and gas obscure the gut wall and obscure masses. It may, however, be a suitable investigation in the frail elderly intolerant of colonoscopy and barium enema in whom a significant malignant gut lesion needs to be excluded.5 6
Q2: What is shown in fig 1 (see p 718)?
Mesenteric arteriography shows the vascular flush of a tumour overlying the sacrum. This was considered to be a vascular lesion in the small bowel. Note the absence of leakage of contrast into the gut lumen typical of angiodysplasia.
Q3: Figure 2 (see p 718) shows a laparotomy specimen consisting of a 4 × 2 cm polypoid lesion on the serosal surface of the mid-small bowel. Histologically this is a myoepithelial hamartoma. What are hamartomas?
Hamartomas are one of the three major groups of developmental tumours; the other two groups are teratomas and embryomas. Hamartomas are tumour-like but primarily non-neoplastic malformations occurring during embryological development. They comprise a abnormal mixture of tissue, which is normal to the site of occurrence. Their capacity for growth normally parallels that of the host.7 In this case the small bowel myoepithelial hamartoma was composed of dilated glandular elements lined by cuboidal epithelium and surrounded by muscle; some are of pancreatic origin. They may cause intestinal obstruction by intussusception or bleeding. As they are non-malignant lesions resection is curative.
There are many causes of melaena and guided by the history and initial imaging investigations a diagnosis can be reached in the vast majority of cases. However in about 5% of cases of gastrointestinal bleeding the cause cannot be identified by standard investigations, which would usually include gastroscopy, colonoscopy and barium enema, and small bowel series. These unidentifiable bleeds are often referred to as obscure gastrointestinal bleeds. Obscure gastrointestinal bleeding is important for geriatricians as the two main causes—small bowel tumours and arteriovenous malformations—are more common in the elderly.8 9 The number of cases of truly unidentifiable haemorrhage becomes ever smaller as new imaging techniques evolve.
The main causes of bleeding from sites within the small intestine are tumours; however these are uncommon. In addition they present a diagnostic challenge, with up to 75% of cases presenting as an emergency. In those patients who present non-acutely imaging proves to be helpful in only half of the cases.10 Malignancies of the small bowel have a combined incidence of 9.9 per million. The four most common histological types are malignant carcinoid, adenocarcinoma, lymphomas, and sarcomas.11 Lymphomas often cause marked destruction to the intestinal wall so acute presentation with perforation or bleed is not uncommon. Adenocarcinomas are generally annular and constricting in nature and therefore obstruction and occult blood loss are not infrequent. Leiomyosarcomas, which arise from the muscle of the small bowel, represent 10% of malignant small bowel neoplasms12 and are histologically often very difficult to distinguish from the benign leiomyoma. The benign tumours of the upper gastrointestinal tract, including the small intestine, are most frequently leiomyomas, adenomatous polyps, lipomas, or schwannomas, which are often incidental or present as haemorrhage or invagination.13 A small bowel myoepithelial hamartoma is a rare cause of melaena in the elderly. We have found no other cases described in the literature. The only other reference to a myoepithelial hamartoma of the small bowel was a case of intussusception in a 2 year old.14
The authors would like to thank Dr J Maggenis, Consultant Radiologist, and Mr J S Elkington, Consultant Surgeon, Wirral Hospital NHS Trust, for figures 1 and 2 respectively.
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