PMC7193195_01
An 80 year-old male with 3 months history of diarrhea and weight loss presented to the emergency department. (a-c) Contrast-enhanced computed tomography (CT) of the abdomen and pelvis obtained in coronal (a) and axial (b and c) planes demonstrates lobulated isoattenuating to the adjacent muscle mass encasing the mesenteric root and extending to the periphery of the vascular bundles (arrows in a and b). There is no evidence of vascular invasion or obstruction. A few smaller soft-tissue deposits were adherent to the serosa of the bowel without bowel obstruction and/or mass effect (arrowhead in c). There was no calcification and no enlarged lymph nodes were appreciated. (d) Contrast-enhanced CT of the abdomen and pelvis obtained 2 years before initial visit demonstrated a focal area of peripheral mesenteric involvement without central mesenteric root deposits (arrows in d).
JCIS-10-24-g001.jpg
PMC7193195_01_JCIS-10-24-g001.jpg
F1
No associated intralesional calcifications or regional lymphadenopathy was present [Figure 1].
Illustration of mesentery amyloid deposition. (a) Microscopic view showing eosinophilic amorphous amyloid deposition in the mesentery tissue (arrow) (hematoxylin and eosin stain, original magnification x400); (b) Microscopic view showing Congo red stained amyloid (arrow) (Congo red stain, original magnification x400). (c) Microscopic view showing apple- green birefringence under polarized light (arrow) (Congo red stain, original magnification x400); (d) Electron microscopic view showing randomly arranged non-branching fibrils with diameters ranging from 5.62 to 8.19 nm (arrow) (Uranyl acetate and lead citrate stain, original magnification x40,000).
JCIS-10-24-g002.jpg
PMC7193195_01_JCIS-10-24-g002.jpg
F2
The pathology showed pale eosinophilic, amorphous, and homogenous amyloid deposition in the mesentery consistent with the diagnosis of a mesenteric amyloidoma [Figure 2a]. The amyloid was positive on Congo red staining [Figure 2b] and displayed apple-green birefringence under polarized light [Figure 2c], consistent with amyloid tissue. By electron microscopy, the amyloid deposits appeared as randomly oriented, non-branching fibrils measuring 5.62-8.19 nm in diameter [Figure 2d].