Primary Localized Amyloidosis of the Intestine: A Pathologist Viewpoint

Abstract

Background: Localized amyloidosis of the intestine is a rare entity, which can clinically masquerade several conditions such as colitis, polyps, and malignant tumors. This study aims to evaluate the clinicopathological features of this entity.

Methods: To evaluate the clinicopathological features of this entity, a comprehensive search of the literature (1960 to 2019) was done using the following keywords: "amyloidosis" and "small intestine" or "duodenum" or "ileum" or "jejunum" or "colon". We identified 756 studies about gastrointestinal amyloidosis. Data were examined for 27 studies about localized intestinal amyloidosis. The clinicopathological features were described.

Results: The age at presentation ranged from 29 to 88 years. The male to female ratio was 3:1. The jejunum and sigmoid colon were the most commonly involved sites. Abdominal pain and intestinal obstruction (small intestine), or rectal bleeding (sigmoid region) were the most common clinical presentations. Colonoscopic findings included wall thickening, mucosal ulcerations (small intestine), and tumor-like masses (colon).

Conclusions: The clinical presentations of localized intestinal amyloidosis depend on the site of the deposition of the amyloid. In most cases, amyloid deposits consisted of light chain protein.

Keywords: Amyloid; Amyloidosis; Colon; Gastrointestinal tract; Rectum; Small intestine.

Figure 1

Flow chart of literature search and study selection for cases of localized intestinal amyloidosis. The inclusion criteria included patients who had amyloid deposition in the intestine without evidence of systemic involvement or an associated condition leading to secondary amyloidosis [42]. The exclusion criteria included patients with one or more of the followings: 1) Evidence of chronic diseases such as collagen vascular disease, that may have led to secondary amyloidosis [42]; 2) Additional organ involvement by amyloidosis; 3) Intestinal symptoms suggestive of amyloidosis but without confirmatory diagnostic tissue biopsy; 4) Plasma cell dyscrasia, myeloma, lymphoplasmacytic disorders or other B-cell malignancies such as Waldenstrom’s macroglobulinemia [5]; 5) Systemic AL type [43]; 6) Laboratory findings revealing positive detection of monoclonal light chains in serum and/or urine [15].

Figure 2

Isolated primary amyloidosis of the intestine (case report): (a - e) Colonic mucosa with deposition of pale eosinophilic amorphous material (star) in the submucosa with abundant deposits of pink amorphous materials with some cracking artifacts, characteristic of amyloid. Focal surface mucosal ulceration is noted. The background mucosa shows focal active inflammation, including cryptitis (arrow), and there is patchy crypt distortion. No granulomas are seen (hematoxylin and eosin: (a) × 20, (b) × 40, (c, d) × 200, and (e) × 400). (f, g) Congo red stain which reveals the characteristic salmon-pink color, confirming the presence of amyloid deposits (Congo red, (f) × 200 and (g) × 400). (h, i) The deposits exhibit characteristic apple-green birefringence under polarized light (Congo red under polarized light ((h) × 200 and (i) × 400).