Diagnostic Ultrasound - Abdomen and Pelvis
Cystic Pancreatic Lesion Helpful Clues for Less Common Diagnoses • Necrotic Pancreatic Ductal Carcinoma ○ Most common pancreatic neoplasm ○ Malignant lesion ○ Commonly in head of pancreas ○ Typically appears as an ill-defined, solid, hypoechoic mass with ductal obstruction ○ May show complex cystic areas due to tumor necrosis, side branch obstruction or adjacent pseudocyst – Uncommon form of common neoplasm ○ Infiltrative appearance ± vascular invasion distinguishes this entity from other solid malignancies that may show cystic change ○ Obstructive symptomatology • Solid Pseudopapillary Neoplasm ○ Tumor with low-grade malignant potential ○ Commonly in the pancreatic tail ○ Well-defined, large heterogeneous echogenic solid and cystic mass ○ Cystic areas are secondary to tumor degeneration and vary in size and morphology ○ Prominent vascular soft tissue components ○ Often shows intratumoral hemorrhage ○ Typically seen in young women (< 35 years) • Cystic Pancreatic Neuroendocrine Tumor ○ All tumors > 5 mm considered malignant ○ Typically round, solid, hypoechoic mass with internal color Doppler flow ○ Central cyst formation may occur due to tumor degeneration – Uncommon form of uncommon neoplasm ○ Identification of hypervascular rim can be challenging ○ Familial syndromes: Multiple endocrine neoplasia type I; von Hippel-Lindau; neurofibromatosis type I; tuberous sclerosis – May have multiple lesions – Occurs in younger patients (< 40 years) • Congenital Cyst ○ True epithelial lining with serous fluid ○ Consider in patients with autosomal dominant polycystic kidney disease, von Hippel-Lindau and cystic fibrosis – Usually multiple; can replace entire pancreas (e.g., in cystic fibrosis) • Lymphoepithelial Cyst ○ Rare, benign, lesion usually in tail of pancreas ○ Nonneoplastic, no malignant behavior ○ Macrocystic morphology, multilocular or unilocular cysts ○ May see characteristic T1 hyperintensity and low T2 signal due to keratin content ○ Almost exclusively in middle-aged to elderly men • Cystic Metastases ○ Pancreatic metastases are uncommon ○ Can occur with renal cell carcinoma, melanoma, breast cancer, lung cancer, gastric cancer, colorectal carcinoma SELECTED REFERENCES 1. Kim YS et al: Rare nonneoplastic cysts of pancreas. Clin Endosc. 48(1):31-8, 2015 2. Goh BK et al: Are the Sendai and Fukuoka consensus guidelines for cystic mucinous neoplasms of the pancreas useful in the initial triage of all suspected pancreatic cystic neoplasms? A single-institution experience with 317 surgically-treated patients. Ann Surg Oncol. 21(6):1919-26, 2014 3. Sahani DV et al: Diagnosis and management of cystic pancreatic lesions. AJR Am J Roentgenol. 200(2):343-54, 2013 4. Megibow AJ et al: The incidental pancreatic cyst. Radiol Clin North Am. 49(2):349-59, 2011 5. Hutchins G et al: Diagnostic evaluation of pancreatic cystic malignancies. Surg Clin North Am. 90(2):399-410, 2010 6. Kalb B et al: MR imaging of cystic lesions of the pancreas. Radiographics. 29(6):1749-65, 2009 Differential Diagnoses: Pancreas Pancreatic Pseudocyst Pancreatic Pseudocyst (Left) Transverse transabdominal ultrasound shows a well-demarcated, anechoic lesion with through transmission ſt in the tail of the pancreas, compatible with a pseudocyst. (Right) Axial CECT in the same patient demonstrates a welldemarcated, low-density cystic lesion with a thin wall in the tail of the pancreas. Note the lack of enhancing components and marked pancreatic atrophy. 921
Cystic Pancreatic Lesion Differential Diagnoses: Pancreas (Left) Transverse transabdominal ultrasound in the region of the pancreas shows a well-circumscribed, unilocular cystic lesion with through transmission. Note the echogenic internal contents and layering debris ſt compatible with a complex pseudocyst. (Right) Transverse transabdominal ultrasound shows pancreatic ductal dilation ſt and 2 wellcircumscribed, elongated fluid collections with internal echoes in the neck and body of the pancreas, compatible with complex pseudocysts from severe pancreatitis. Pancreatic Pseudocyst Pancreatic Pseudocyst (Left) Transverse transabdominal ultrasound shows a hyperechoic, solidappearing mass in the head of the pancreas with small cystic components st and more echogenic center ſt. (Right) Corresponding axial CECT better characterizes numerous small cysts st within the lesion, separated by thin septa, which appear more coalescent centrally ſt. Serous Cystadenoma of Pancreas Serous Cystadenoma of Pancreas (Left) Transverse transabdominal ultrasound shows a heterogeneous lesion in the tail of the pancreas composed of innumerable tiny cysts separated by linear septations, which result in a hyperechoic appearance due to the highly reflective interfaces (Right) Axial CECT shows the classic honeycomb appearance of a serous cystadenoma : A microcystic lesion with thin enhancing septa delineating small cysts. Note the scattered central calcifications and lack of wall thickening, which are also typical features. Serous Cystadenoma of Pancreas Serous Cystadenoma of Pancreas 922
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Cystic Pancreatic Lesion<br />
Differential Diagnoses: Pancreas<br />
(Left) Transverse<br />
transabdominal ultrasound in<br />
the region of the pancreas<br />
shows a well-circumscribed,<br />
unilocular cystic lesion <br />
with through transmission.<br />
Note the echogenic internal<br />
contents <strong>and</strong> layering debris<br />
ſt compatible with a complex<br />
pseudocyst. (Right) Transverse<br />
transabdominal ultrasound<br />
shows pancreatic ductal<br />
dilation ſt <strong>and</strong> 2 wellcircumscribed,<br />
elongated fluid<br />
collections with internal<br />
echoes in the neck <strong>and</strong> body of<br />
the pancreas, compatible with<br />
complex pseudocysts from<br />
severe pancreatitis.<br />
Pancreatic Pseudocyst<br />
Pancreatic Pseudocyst<br />
(Left) Transverse<br />
transabdominal ultrasound<br />
shows a hyperechoic, solidappearing<br />
mass in the head of<br />
the pancreas with small cystic<br />
components st <strong>and</strong> more<br />
echogenic center ſt. (Right)<br />
Corresponding axial CECT<br />
better characterizes numerous<br />
small cysts st within the<br />
lesion, separated by thin<br />
septa, which appear more<br />
coalescent centrally ſt.<br />
Serous Cystadenoma of Pancreas<br />
Serous Cystadenoma of Pancreas<br />
(Left) Transverse<br />
transabdominal ultrasound<br />
shows a heterogeneous lesion<br />
in the tail of the pancreas<br />
composed of innumerable tiny<br />
cysts separated by linear<br />
septations, which result in a<br />
hyperechoic appearance due<br />
to the highly reflective<br />
interfaces (Right) Axial CECT<br />
shows the classic honeycomb<br />
appearance of a serous<br />
cystadenoma : A<br />
microcystic lesion with thin<br />
enhancing septa delineating<br />
small cysts. Note the scattered<br />
central calcifications <strong>and</strong> lack<br />
of wall thickening, which are<br />
also typical features.<br />
Serous Cystadenoma of Pancreas<br />
Serous Cystadenoma of Pancreas<br />
922
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