DOI:10.2214/AJR.05.1670
AJR 2006; 186:S445-S448
© American Roentgen Ray Society
AJR Teaching File: Chronic Nausea and Vomiting with Abdominal Pain
Jeremy L. Friese1 and
Amy K. Hara2
1 Department of Diagnostic Radiology, Mayo Clinic, Rochester, MN.
2 Department of Diagnostic Radiology, Mayo Clinic Scottsdale, 13400 E Shea
Blvd., Scottsdale, AZ 85259.
Received September 20, 2005;
accepted after revision December 19, 2005.
CONTINUING MEDICAL EDUCATION
This AJR Teaching File article is available for CME and SAM credit
for completing the accompanying SAM on p.
S442. CME and SAM
credit are free to ARRS members and may be purchased by nonmembers for $10.00
each. Detailed information including objectives, disclosure information, and
how to obtain CME and SAM credit can be found at
www.arrs.org
by selecting Journals/Integrative Imaging.
Address correspondence to A. K. Hara
(hara.amy{at}mayo.edu).
Keywords: annular pancreas • gastrointestinal imaging • intraductal papillary mucinous neoplasm • pancreas
Case History
A 67-year-old woman presents with worsening chronic nausea, vomiting, and
abdominal pain.
Radiologic Description
Upper gastrointestinal imaging (Fig.
1A) shows mild narrowing of the second portion of duodenum.
Contrast-enhanced CT (Figs. 1B,
1C,
1D, and
1E) shows pancreatic tissue
abnormally located laterally in relation to the descending duodenum,
consistent with an annular pancreas. A cystic mass is seen in the pancreatic
head that communicates with a mildly dilated main pancreatic duct and a
dilated duct in the annular portion of the pancreas. MRI (Figs.
1F and
1G) shows similar findings to
CT. The annular duct is not well visualized on 3D MR cholangiopancreatography
(MRCP) (Fig. 1G). ERCP
(Fig. 1H) shows a
normal-appearing pancreatic duct with no visualization of the annular portion.
Surgical pathology confirms an intraductal papillary mucinous neoplasm (IPMN)
in the annular pancreas. Gross pathology
(Fig. 1I) shows the annular
portion of the pancreas and the dilated duct. The duct in the annular portion
was not seen on MRCP or ERCP because of obstructing mucin.
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Fig. 1B —67-year-old woman with worsening chronic nausea, vomiting, and
abdominal pain. Contrast-enhanced CT scans show pancreatic tissue abnormally
located laterally in relation to descending duodenum (D), consistent with
annular pancreas. Note cystic mass (arrowhead, D and E)
in pancreatic head that communicates with mildly dilated main pancreatic duct
and dilated duct in annular portion of pancreas.
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Fig. 1C —67-year-old woman with worsening chronic nausea, vomiting, and
abdominal pain. Contrast-enhanced CT scans show pancreatic tissue abnormally
located laterally in relation to descending duodenum (D), consistent with
annular pancreas. Note cystic mass (arrowhead, D and E)
in pancreatic head that communicates with mildly dilated main pancreatic duct
and dilated duct in annular portion of pancreas.
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Fig. 1D —67-year-old woman with worsening chronic nausea, vomiting, and
abdominal pain. Contrast-enhanced CT scans show pancreatic tissue abnormally
located laterally in relation to descending duodenum (D), consistent with
annular pancreas. Note cystic mass (arrowhead, D and E)
in pancreatic head that communicates with mildly dilated main pancreatic duct
and dilated duct in annular portion of pancreas.
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Fig. 1E —67-year-old woman with worsening chronic nausea, vomiting, and
abdominal pain. Contrast-enhanced CT scans show pancreatic tissue abnormally
located laterally in relation to descending duodenum (D), consistent with
annular pancreas. Note cystic mass (arrowhead, D and E)
in pancreatic head that communicates with mildly dilated main pancreatic duct
and dilated duct in annular portion of pancreas.
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Fig. 1F —67-year-old woman with worsening chronic nausea, vomiting, and
abdominal pain. MR images show findings similar to CT. Annular duct is not
well visualized on 3D MR cholangiopancreatography (MRCP) image (G).
Arrowhead in G indicates cystic mass.
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Fig. 1G —67-year-old woman with worsening chronic nausea, vomiting, and
abdominal pain. MR images show findings similar to CT. Annular duct is not
well visualized on 3D MR cholangiopancreatography (MRCP) image (G).
Arrowhead in G indicates cystic mass.
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Fig. 1I —67-year-old woman with worsening chronic nausea, vomiting, and
abdominal pain. Surgical pathology confirms intraductal papillary mucinous
neoplasm in annular pancreas. Photograph from gross pathology shows annular
portion of pancreas (arrows) and dilated duct surrounding duodenum.
Duct in annular portion was not seen on MRCP or ERCP because of obstructing
mucin.
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Differential Diagnosis
The differential diagnosis in this patient is pancreatic adenocarcinoma,
annular pancreas, IPMN of the pancreas, and IPMN in an annular pancreas.
Diagnosis
The diagnosis is IPMN in an annular pancreas.
Commentary
Intraductal papillary mucinous neoplasms (IPMNs) of the pancreas are unique
pancreatic tumors made of papillary projections of ductal epithelium that
produce mucin and result in main and side branch ductal dilatation. Most
patients present after age 60 with nonspecific symptoms such as abdominal
pain, fatigue, or weight loss. Diagnosis is typically made with CT. Imaging
features include dilatation of the main pancreatic duct or cystic lesions
within or connecting to dilated ducts
[1-3].
Endoscopic sonography and ERCP are also useful and allow tissue diagnosis.
Recurrence and survival are directly related to histopathology; invasive
IPMN has a 5-year survival rate of 36%, whereas noninvasive IPMN has a
survival rate of 85% [4,
5]. To date few studies have
evaluated radiologic characteristics to predict invasiveness. Recently, one
study reported a 100% negative predictive value when three criteria are absent
(solid nodule, extension beyond the gland, and biliary obstruction or stent)
[6]. This may allow some
patients with a high operative risk to be followed, but the current consensus
is that surgical resection is the recommended treatment for all IPMNs
[7].
An annular pancreas is a rare congenital abnormality occurring in
approximately one in 7,000 adults. This is thought to be due to a malformation
during pancreatic development in which a derivative of the ventral portion of
the embryologic pancreas encircles the second portion of the duodenum, usually
superior to the ampulla. Age at presentation is bimodal, with peaks in infancy
and in the fifth and sixth decades; presenting symptoms are usually secondary
to duodenal obstruction. Characteristic imaging findings include a stricture
on upper gastrointestinal barium examination and normal pancreatic tissue
encircling the duodenum on CT and MRI
[8]. Rarely, a disorder such as
pancreatitis or neoplasm is found in the annular pancreas. The abnormal course
of the pancreatic duct can also be typically shown on MRCP or ERCP; however,
in this unusual case, both examinations were falsely negative because of
obstructing mucin in the annular portion of the duct.
Objective
The objective of this teaching article is to show an unusual case of
intraductal papillary mucinous neoplasm (IPMN) occurring in an annular
pancreas.
Conclusion
Annular pancreas is a rare congenital anomaly that can be easily overlooked
on CT or MRI. As thin-slice imaging becomes more routine with MDCT scanners,
this entity may be more easily diagnosed. In this unusual case of an IPMN
occurring in an annular pancreas, a pitfall at MRCP and ERCP is shown, in that
obstructing mucin obscured the detection of the annular portion of the
duct.
References
- Silas AM, Morrin MM, Raptopoulos V, Keogan MT. Intraductal
papillary mucinous tumors of the pancreas. AJR2001; 176:179
-185[Free Full Text]
- Taouli B, Vilgrain V, O'Toole D, Vullierme MP, Terris B, Menu Y.
Intraductal papillary mucinous tumors of the pancreas: features with
multimodality imaging. J Comput Assist Tomogr2002; 26:223
-231[CrossRef][Medline]
- Taouli B, Vilgrain V, Vullierme MP, et al. Intraductal papillary
mucinous tumors of the pancreas: helical CT with histopathologic correlation.
Radiology 2000;217
: 757-764[Abstract/Free Full Text]
- Chari ST, Yadav D, Smyrk TC, et al. Study of recurrence after
surgical resection of intraductal papillary mucinous neoplasm of the pancreas.
Gastroenterology 2002;123
: 1500-1507[CrossRef][Medline]
- Feldman M, Friedman LS, Sleisinger MH. Sleisenger &
Fordtran's gastrointestinal and liver disease, 7th ed. St. Louis,
MO: Elsevier, 2002: 867-868
- Friese JL, Fletcher JG, Chari ST, et al. Prediction of invasiveness
of pancreatic intraductal papillary mucinous neoplasm (IPMN) using computed
tomography. AJR 2004;182
[American Roentgen Ray Society 104th Annual Meeting
Abstract Book suppl]: 63
- Sugiura H, Kondo S, Islam HK, et al. Clinicopathologic features and
outcomes of intraductal papillary-mucinous tumors of the pancreas.
Hepatogastroenterology 2002;49
: 263-267[Medline]
- Jadvar H, Mindelzun RE. Annular pancreas in adults: imaging
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Case History
Radiologic Description
