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Gastrointestinal manifestations of amyloidosis include dysmotility and pseudo-obstruction.1,2 Here, we report an exceptional case of acute small bowel obstruction followed by perforation in a patient with documented light chain amyloidosis (AL).
A 39 year old Chinese woman had a 10 year history of κ light chain myeloma with associated endstage renal failure requiring dialysis. Her final presentation was precipitated by the acute onset of abdominal pain and vomiting, diagnosed as small bowel obstruction. Laporatomy disclosed jejunal perforation, for which segmental resection was performed. She subsequently died of postoperative complications.
Grossly, the 16 cm long jejunum showed multiple areas of haemorrhagic infarction with one mural perforation site. Histologically, congophilic potassium permanganate resistant green birefringent amyloid was deposited preferentially in vascular channels, particularly in the submucosa, although mesenteric vessels were also involved, and some contained vestiges of organising thrombi. A lesser degree of amyloid deposition was seen within muscularis mucosae and propria, but none was seen in neural plexuses. There was secondary mural acute and chronic ischaemic damage. Ultrastructurally, the amyloid consisted of haphazardly arranged linear non-branching fibrils of 7–15 nm diameter.
The pathological findings were those of AL, preferentially involving vascular channels, with secondary occlusion, and complicating ischaemia with perforation.
This case highlights the clinicopathological differences between the various classes of amyloidosis. Although AL may involve any viscus, the mesenchymal tissues are usually affected.3
Gastrointestinal involvement is more common in secondary amyloidosis (AA), especially the mesenteric plexus and vessels,2 whereas β2 microglobulin amyloid (AH) is usually deposited in periarticular sites.3 Although AH was a consideration in this case because of the history of dialysis,3 the ultrastructural features of β2 microglobulin are thick curvilinear fragments of 8–10 nm diameter.4
Overall, acute bowel infarction and perforation in amyloidosis are rare, and are usually seen only in cases of systemic disease. More commonly, AL results in chronic intermittent bowel obstruction as a result of gut wall deposition of amyloid.2 The rare cases of gut perforation related to AA have implicated preferential amyloid vascular deposition. In this unique case, the clinical symptoms of acute bowel obstruction complicated by perforation can be explained by an unusual pattern of amyloid deposition in AL, involving both blood vessels and muscularis. Recognition of this rare possibility may facilitate earlier diagnosis in this disease.
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