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A 70-year-old man presented with anorexia, altered bowel habit and weight loss. He had a history of heart failure and rheumatoid arthritis. Clinical examination showed rheumatoid deformity and pedal oedema. Laboratory investigations demonstrated microcytic anaemia, eosinophilia and hypoalbuminaemia. Barium enema and contrast-enhanced abdominal computed tomography (CT) were performed (figures 1 and 2, respectively).
- What are the radiological signs on figures 1 and 2 ?
- What is the differential diagnosis for each ?
- Are there any common denominators ?
The barium enema (figure 1) shows loss of the normal haustral pattern and the mucosa appears granular. There is widening of the presacral space (A). The bladder, opacified by prior CT enhancement, is narrowed and elongated (B). On the CT scan (figure 2), the intra-abdominal fat is of similar attenuation to the water density of a simple right renal cyst. The mesenteric and pararenal fat has a misty appearance with thickening of Gerota's fascia.
The differential diagnosis for the CT appearances is summarised in box FB1.1 The differential diagnosis for the changes on the barium enema is summarised in boxFB2.2The correct diagnosis is suggested radiographically by radiating strands of soft-tissue density that surround the central vessels without displacing them. Generalised adenopathy is not seen. Typically a halo of fat surrounds the vessels in the mesentery
The common denominators are ulcerative colitis and amyloidosis. Amyloidosis is supported by the clinical history of rheumatoid arthritis.
Rectal biopsy showed no evidence of ulcerative colitis or amyloidosis. Laparoscopic biopsy of the mesenteric fat confirmed amyloid deposited in the vessel walls and as rings in the adipose tissue. Further stains confirmed amyloidosis associated with inflammatory disease (AA amyloidosis). Amyloid was also seen in biopsies of the pleura, bladder wall and prostate. Over the next 20 months he became increasingly symptomatic with cardiac failure, became refractive to treatment, and died.
The clinical and pathological manifestations of amyloid disease were first reported in the mid-1800s. Amyloidosis is a rare systemic disease caused by extracellular deposition of a protein polysaccharide in various organs leading to hypoxia, mucosal oedema, haemorrhage, ulceration, mucosal atrophy and muscle atrophy. Although it is usually seen in a systemic form, 10–20% of cases can be localised. The localised form of amyloidosis is site-limited and does not progress to systemic involvement. Systemic amyloidosis is sub-classified into an idiopathic primary form and a secondary or reactive form. Patients with primary amyloidosis have no underlying disease. Men are affected more often than women, the mean age at presentation is 55–60 years. Some causes of secondary amyloidosis are multiple myeloma (10–15%), rheumatoid arthritis (20–25%), tuberculosis (50%), or familial Mediterranean fever (26–40%).
Infiltration of the gastrointestinal tract (GIT) with amyloid, as demonstrated by microscopic examination, is not unusual. Symmers reported GIT findings in 70% of autopsy cases of primary amyloidosis,3 while 75% of rectal biopsies were positive for amyloid in a study of 200 patients reported by Blum and Sohar.4 Aspiration biopsy of abdominal fat has a sensitivity of 82% and 100% specificity.5 Gilatet al demonstrated involvement of the digestive tract at autopsy in 68 of 70 cases of systemic amyloidosis.6 Amyloid is deposited around small blood vessels in the submucosa and can result in occlusion, ischaemia, and ultimately infarction of bowel wall. Damage to musculature and nervous elements may cause alterations in gut motility.
Patients with GIT involvement are often asymptomatic, but widespread dysfunction may occur. The clinical manifestations are equally non-specific and diverse, including dysphagia, bowel obstruction, diarrhoea, haemorrhage, or simply diffuse abdominal discomfort with weight loss.
The radiographic abnormalities most commonly reported include motor dysfunction, nodular and thickened mucosal folds, ulcerations, mucosal atrophy, malabsorption pattern, hepatosplenomegaly, distinct intraluminal and intramural masses, and obstruction at multiple sites in the GIT. Amyloid fibrils have an affinity for calcium, and radiographically detectable calcified amyloid deposits may occur in both primary and secondary amyloidosis. Carlson et al reviewed 230 cases of primary systemic amyloidosis seen at the Mayo Clinic over a 10-year period. In 47 patients who had amyloidosis diagnosed from a GIT biopsy site or had GIT involvement at autopsy, 20 had abnormal radiological reports (summarised in the table).7
CT and magnetic resonance imaging findings are non-specific, often mimicking both inflammatory and neoplastic processes. GIT involvement with amyloidosis is common. As radiological findings, when positive, are non-specific, definitive diagnosis depends on histology.
Mesenteric amyloidosis secondary to rheumatoid arthritis.