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Calcified Pancreatic Lesions: Differential Dx

Overview of Calcified Pancreatic Lesions

Pancreatic Neuroendocrine Tumor

Well-circumscribed mass with avid enhancement on arterial phase images
Syndromic tumors are detected earlier → typically smaller in size when compared to non-syndromic tumors
- Non-syndromic often >5 cm in size with cystic and necrotic degeneration
Calcification Pattern:
- Most common calcified solid pancreatic mass
- Often coarse and irregular calcifications
- Central calcification more common than eccentric
- Small masses can rarely appear completely calcified
- Non-syndromic, large masses with central necrosis are more likely to develop calcification

Pancreatic Neuroendocrine Tumor

Multiple gastrinomas with calcification resulting in severe gastric wall thickening due to Zollinger-Ellison syndrome

Serous Cystadenoma

Benign, usually asymptomatic, well-circumscribed mass with a lobulated contour
“Grandmother tumor”: preponderance in older women
Most commonly appears as a “microcystic” adenoma with multiple (>6) small (<2 cm) internal cysts
10-25% have “macrocystic” appearance (usually unilocular)
Peripheral rim of enhancement
Calcification Pattern:
- Peripheral thin rim of calcification is most common
- Central scar with central dystrophic calcification
- Thin calcification along radiating septations

Serous Cystadenoma

Subtle internal calcification in a serous cystadenoma with honeycomb or ‘sponge’ pattern

Serous Cystadenoma

As in this case, calcifications in serous cystadenoma are often located at the center of the lesion in the vicinity of the central scar

Mucinous Cystic Neoplasm

Premalignant or frankly malignant cystic lesion, most often diagnosed in middle-aged females (“mother tumor”)
Unilocular or multilocular cystic neoplasm
- “Macrocystic” pattern: Few (<6) large (>2 cm) cystic locules
Most commonly located in the pancreatic body or tail
Thick wall, mural nodularity, or soft tissue component may be present in cases with invasive malignancy
Calcification Pattern:
- 16% of lesions are calcified
- Peripheral curvilinear calcifications
- Calcification of septations

Mucinous Cystic Neoplasm

Calcification in mucinous cystic neoplasms (MCN) tend to be peripheral, thin, and curvilinear.

Mucinous Cystic Neoplasm

Note the presence of subtle peripheral curvilinear calcification at the margin of this MCN. The location of the lesion, the age and gender of the patient, and the pattern of calcification should allow a confident, specific diagnosis.

Solid and PseudopapillaryNeoplasm

Well-defined, large, solid, heterogeneous pancreatic mass with a thick, enhancing capsule
Variable internal cystic and hemorrhagic components, but most often solid
>90% occur in women
Almost always in patients <35 years old
Usually no biliary or pancreatic ductal obstruction
Calcification Pattern:
- Up to 50% of lesions are calcified
- Peripheral or central calcifications

Solid and PseudopapillaryNeoplasm

SPEN tumors very commonly demonstrate calcification, perhaps dystrophic in nature related to the frequent intralesional hemorrhage present within these lesions.

Solid and PseudopapillaryNeoplasm

Intraductal Papillary Mucinous Neoplasm (IPMN)

Mucin-producing tumor originating from the main pancreatic duct and/or duct side branches
Side-branch IMPN: Cystic lesion communicating with main duct, often multiple
Main-duct IMPN: Markedly dilated, tortuous main duct (segmental or diffuse); overlying pancreas may be atrophic
Risk of transformation into invasive carcinoma
Calcification Pattern:
- Side-branch IPMN demonstrate peripheral or septal calcification in 20% of patients
- Main-duct IPMN may demonstrate amorphous calcifications within dilated main pancreatic duct

Intraductal Papillary Mucinous Neoplasm (IPMN)

Side-branch IPMN are reported to calcify in ~20%, although our own experience suggests (anecdotally) that calcification is relatively uncommon in IPMN

Intraductal Papillary Mucinous Neoplasm (IPMN)

Main-duct IPMN with markedly dilated pancreatic duct containing amorphous calcifications. While described as a common feature in the literature, our own experience is that this is a relatively rare imaging pattern.

Other Solid or CysticPancreatic Masses

Pancreatic Pseudocyst:
- Chronic pseudocysts may rarely demonstrate peripheral calcifications, although the majority of pseudocysts do not calcify
Pancreatic Metastases:
- Overall, metastases to the pancreas are rare, with the most common metastasis from renal cell carcinoma
- Metastatic disease from a gastrointestinal mucinous adenocarcinoma (such as colon, gastric, etc.) may be associated with calcification

Pancreatic Pseudocyst

Pancreatic Metastasis

Beautiful example of a mucinous colon cancer metastasis to the pancreas with internal stippled calcifications

Which pancreatic mass does not calcify?

Conventional pancreatic adenocarcinoma virtually never demonstrates calcification, with the exception of rare pancreatic mucinous adenocarcinomas

Unusual pancreatic mucinous adenocarcinoma with internal calcification

Chronic Pancreatitis

Parenchymal fibrosis from chronic inflammation, often secondary to alcohol abuse
Features of chronic pancreatitis include parenchymal calcifications, dilated/beaded pancreatic duct, parenchymal atrophy, pseudocysts, and intraductal stones
Calcification Pattern:
- Calcification can be either parenchymal or intraductal
- Usually multiple
- Ranging in size from puntacte to large (up to 1 cm)
- Most often in pancreatic head (possibly clustered)
Degree of pancreatic calcification related to severity of disease
Chronic pancreatitis can manifest as a focal fibroinflammatory mass (usually in head) which can also demonstrate calcification

Chronic Pancreatitis

Focal calcified mass in the pancreatic head in patient with chronic pancreatitis. As mentioned previously, the presence of calcification within this mass argues strongly against the possibility of pancreatic adenocarcinoma

Mimics of Primary PancreaticCalcifications

Peripancreatic Vascular Calcifications:
- “Tram Track” atherosclerotic calcification of the splenic artery
- Peripheral or eggshell calcification of splenic artery aneurysm
- Calcification of a chronic splenic vein thrombus
Choledocholithiasis:
- Calcified stone in the distal common bile duct (CBD) can mimic a pancreatic head calcified lesion
- Often associated with biliary obstruction
Duodenal Diverticulum:
- High density contrast material in a diverticulum (oral contrast, medication) can mimic calcified pancreatic mass

Conclusion

Selection of an appropriate MDCT protocol is essential for accurately diagnosing and differentiating pancreatic lesions
Calcification patterns can help to narrow the differential diagnosis when confronted with a solid or cystic pancreatic mass
Solid mass:
- Pancreatic adenocarcinoma almost never contains calcifications
- Neuroendocrine tumor: Most common calcified solid pancreatic mass
Cystic Mass:
- Serous cystadenoma, mucinous cystic neoplasm, SPEN, and IPMN can all demonstrate calcifications (with variable morphology)

References

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Acknowledgements

Sameer Ahmed MD
Siva P. Raman MD
Elliot K. Fishman MD