DOI:10.2214/AJR.04.1134
AJR 2005; 185:1187-1189
© American Roentgen Ray Society
Focal Amyloidoma of the Small Bowel Mimicking Adenocarcinoma on CT
Amit M. Saindane1,
Mariela Losada2 and
Michael Macari1
1 Department of Radiology, Division of Abdominal Imaging, New York University
School of Medicine, 560 First Ave., Ste. HW 211, New York, NY 10016.
2 Department of Pathology, New York University School of Medicine, New York, NY
10016.
Received July 19, 2004;
accepted after revision November 15, 2004.
Address correspondence to M. Macari
(michael.macari{at}med.nyu.edu).
Introduction
The amyloidoses are a group of disorders characterized histopathologically
by the extracellular deposition of insoluble fibrillar proteins. Deposition of
amyloid proteins is usually systemic with variable involvement of different
organ systems; however, approximately 15% of cases are localized to a single
organ or organ system [1].
Involvement of the small bowel is frequent in systemic forms of amyloidosis
[2], and clinical presentations
include malabsorption, gastrointestinal bleeding, and dysmotility,
occasionally presenting as chronic or acute pseudoobstruction
[3].
Radiographic abnormalities of the small bowel during barium small-bowel
series include delayed transit time, segmental narrowing, small-bowel
dilatation, thickening of the valvulae conniventes, fine mucosal granularity,
and small polypoid protrusions
[2]. CT examination is
nonspecific, but may show small-bowel dilatation, symmetric bowel wall
thickening, a "double-halo" appearance, mesenteric infiltration,
and mesenteric adenopathy [4,
5]. Amyloidosis localized to
the small bowel without extraintestinal manifestations is rare and typically
presents as multiple polypoid lesions or large amyloid tumors of the duodenum
and jejunum [6,
7]. We report a case of
small-bowel obstruction secondary to an amyloid tumor of the jejunum that
simulated an adenocarcinoma on CT and small-bowel series.
Case Report
A 74-year-old man with a medical history of hypertension and coronary
artery disease presented to the emergency department with acute onset of
sharp, constant, and nonradiating epigastric pain that was not accompanied by
nausea or vomiting. He was afebrile with stable vital signs. Findings on
physical examination were significant for absent bowel sounds and a soft but
moderately distended abdomen with mild upper abdominal tenderness. The
patient's stool was Hemoccult-negative (Beckman Coulter). Laboratory studies
including complete blood count, serum electrolytes, liver function tests, and
coagulation studies were within the normal limits.
A CT examination of the abdomen and pelvis with oral and IV contrast
material was performed on admission and revealed evidence of small-bowel
obstruction with a soft-tissue mass at the zone of transition (Figs.
1A and
1B). A small-bowel series
performed the next day corroborated the presence of an ulcerated obstructing
mass in the jejunum, highly suggestive of adenocarcinoma
(Fig. 1C).
View larger version (136K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1A —74-year-old man with acute onset of epigastric pain. Axial
contrast-enhanced CT image of abdomen shows mild small-bowel dilatation with
obstructing soft-tissue attenuation mass (arrow) in jejunum.
|
|
The patient underwent laparotomy that showed moderately dilated small
bowel, a short segment of soft but markedly thickened jejunum, and palpable
enlarged lymph nodes in the adjacent mesentery. A segment of 20 cm of jejunum
was resected. Gross pathologic examination revealed a well-demarcated and
irregular area of wall thickening with a granular, ulcerated, and hemorrhagic
mucosal surface measuring 6.7 cm in greatest dimension
(Fig. 1D). The wall measured
0.5–1.5 cm in thickness, and there was extensive mucosal and submucosal
hemorrhage with focal ischemic necrosis
(Fig. 1E). Both ends of the
specimen showed normal gross appearance. Multiple enlarged calcified
mesenteric lymph nodes were present.
View larger version (104K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1D —74-year-old man with acute onset of epigastric pain.
Photograph of gross pathologic specimen shows thickened segment of jejunum
with irregular borders, ulceration, and necrosis (arrow).
|
|
Microscopically, there were extensive diffuse amyloid deposits involving
the entire wall thickness, with destruction of the mucosa and deep
infiltration into the muscularis propria and lymph nodes
(Fig. 1F). Amyloid angiopathy
with luminal narrowing was prominent. The amyloid nature of the deposits was
confirmed by crystal violet and Congo red stains. Immunohistochemical studies
showed staining of amyloid deposits with anti-
antibody and no
significant staining with anti-
, anti–amyloid A protein, or
transthyretin antibodies, indicating that the amyloid protein is
immunoglobulin (light chain type). Other unrelated biopsy slides from
this patient were reviewed and showed absence of amyloid deposition.
The patient was discharged from the hospital in stable condition 5 days
after surgery. Further workup showed a monoclonal IgG spike in the
serum and no Bence Jones proteinuria. There was no clinical, laboratory, or
radiographic evidence of extraintestinal involvement of amyloidosis.
Discussion
Amyloidosis of the small bowel may have numerous clinical presentations,
including malabsorption, gastrointestinal bleeding, abdominal pain, and
pseudoobstruction [3]. However,
it is unusual for amyloidosis to manifest as a mechanical small-bowel
obstruction, as was the case in our subject. Amyloid tumors of the duodenum
and jejunum are rare [6,
7], and the more likely
differential diagnostic considerations for these masses include primary
small-bowel neoplasms and metastatic disease
[8]. Although primary neoplasms
of the small bowel are relatively uncommon, the appearance of the ulcerated
annular mass on CT and small-bowel series in this case was highly suggestive
of neoplasm, most likely primary small-bowel adenocarcinoma.
The pathophysiology of amyloidosis in the small bowel is likely
multifactorial. Histopathologically, small-bowel amyloidosis is characterized
by diffuse deposition of amyloid proteins in the mucosa, lamina propria,
muscularis mucosae, and muscularis propria and within blood vessel walls
[2]. Arteriolar deposition is
thought to lead to ischemia, resulting in mucosal erosion and ulceration,
potentially leading to gastrointestinal bleeding or malabsorption. Dysmotility
is postulated to be due to amyloid protein deposition within the muscularis
propria or myenteric plexus
[3].
The development of large amyloid tumors may represent an extreme in the
spectrum of ischemic injury to the small bowel. Focal ischemia due to the
selective deposition of amyloid proteins in the mesenteric vasculature could
lead to localized small-bowel wall thickening, submucosal edema, hemorrhage,
and mucosal ulceration. An element of the masslike appearance of amyloid
tumors appears to be related to massive amyloid protein deposition throughout
the bowel wall. The abrupt onset of our patient's symptoms rather than a
slowly progressive pattern of obstruction suggests a superimposed acute
process such as submucosal hemorrhage or ischemia within the mass. The reasons
for the focal tumoral deposition of amyloid proteins and predilection for
selective involvement of the proximal small bowel are unclear.
The presumption of localized amyloidosis is potentially problematic because
it is possible that pathology of the small bowel may occur in the setting of
subclinical extraintestinal disease or may represent an early manifestation of
systemic amyloidosis. The distinction is of some consequence, because
prognosis for patients with systemic amyloidoses is usually poor, whereas that
for patients with localized disease is generally good
[1]. Clinically, it may not be
practical to extensively evaluate every potential extraintestinal site of
amyloid involvement because, in the limited experience with amyloid tumors of
the small bowel, patients do not appear to experience recurrence of intestinal
disease or progression to systemic disease.
We believe that although it is a rare entity, in the right clinical context
amyloid tumor should be a consideration in the differential diagnosis for
intraluminal masses of the proximal small bowel.
References
- Scott PP, Scott WW Jr, Siegelman SS. Amyloidosis: an overview.
Semin Roentgenol 1986;21
: 103–112[CrossRef][Medline]
- Tada S, Iida M, Yao T, et al. Gastrointestinal amyloidosis:
radiologic features by chemical types. Radiology1994; 190:37
–42[Abstract/Free Full Text]
- Koppelman RN, Stollman NH, Baigorri F, Rogers AI. Acute small bowel
pseudo-obstruction due to amyloidosis: a case report and literature review.
Am J Gastroenterol 2000;95
: 294–296[CrossRef][Medline]
- Kim SH, Han JK, Lee KH, et al. Abdominal amyloidosis: spectrum of
radiologic findings. Clin Radiol 2003;58
: 610–620[CrossRef][Medline]
- Araoz PA, Batts KP, MacCarty RL. Amyloidosis of the alimentary
canal: radiologic–pathologic correlation of CT findings.
Abdom Imaging 2000;25
: 38–44[CrossRef][Medline]
- Peny MO, Debongnie JC, Haot J, Van Gossum A. Localized amyloid
tumor in small bowel. Dig Dis Sci 2000;45
:1850
–1853[CrossRef][Medline]
- Hamaya K, Kitamura M, Doi K. Primary amyloid tumors of the jejunum
producing intestinal obstruction. Acta Pathol Jpn1989; 39:207
–211[Medline]
- Buckley JA, Fishman EK. CT evaluation of small bowel neoplasms:
spectrum of disease. RadioGraphics 1998;18
: 379–392[Abstract]
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
Top
Introduction
Case Report
