Document resource
I read with great interest the article by Skinner et al, which presents impressive images of the haemorrhagic ileal ulcer caused by amyloid light-chain (AL) amyloidosis.1 I congratulate the authors on their decision to perform surgery to treat the uncontrolled haemorrhage, and I fully agree that the presence of plasma cell dyscrasias should raise suspicion of gastrointestinal amyloidosis. I would like to comment on the possible pathological basis for the difficulty in making a preoperative diagnosis through biopsy in this case. Patterns of amyloid deposition are associated with clinical and endoscopic features.2 In amyloid A protein (AA) amyloidosis, granular amyloid deposition mainly occurs in the propria mucosae, resulting in a fine granular appearance and mucosal friability. Consequently, AA amyloidosis often presents with diarrhoea, malabsorption and protein-losing gastroenteropathy. In contrast, amyloid deposition in the muscularis mucosae, submucosa and muscularis propria is dominant in AL amyloidosis. This leads to thickened folds, polypoid protrusions and haematoma. AL amyloidosis typically presents with constipation, motility disorders or haemorrhage. Deposition of AL amyloid in submucosal vessel walls causes vascular fragility, resulting in submucosal haematoma and ischaemic ulcer.3 4 Additionally, acquired factor X deficiency associated with AL amyloidosis may contribute to haematoma formation. A pathological study proposes that, if systemic amyloidosis is clinically suspected, AA amyloidosis should be sought preferentially in biopsies of the upper gastrointestinal tract, while AL amyloidosis (especially the lambda subtype) should be sought in biopsies of the large intestine enclosing submucosal layers.4 In conclusion, Skinner’s excellent images highlight the importance of considering amyloidosis when investigating cases of gastrointestinal bleeding. As biopsies of ulcers may collect necrotic tissue or cause further bleeding, deeper biopsies of the adjacent mucosa may be recommended when amyloidosis is suspected.