Classification of Pancreatic Tumors - Radiology Made Easy

Step 1 - The Master Split

PANCREATIC TUMORS
├── SOLID
│   ├── Hypovascular (most common)
│   │   ├── Pancreatic Ductal Adenocarcinoma (PDAC) ← 85% of all
│   │   └── Acinar Cell Carcinoma (ACC)
│   └── Hypervascular
│       └── Pancreatic Neuroendocrine Tumor (pNET)
│           (also: metastases from RCC, HCC, melanoma)
└── CYSTIC
    ├── Benign (almost always)
    │   └── Serous Cystadenoma (SCA)
    ├── Premalignant / Mucinous
    │   ├── Mucinous Cystic Neoplasm (MCN)
    │   └── IPMN (main-duct / branch-duct / mixed)
    └── Mixed Solid-Cystic
        └── Solid Pseudopapillary Neoplasm (SPN)

SOLID TUMORS

1. Pancreatic Ductal Adenocarcinoma (PDAC) - 85%

"Typical imaging features of pancreatic cancer on dynamic CT include a hypoattenuating mass compared with the adjacent pancreatic parenchyma in the late arterial and portal venous phases due to decreased vascularity within the tumoral tissue and desmoplastic stroma." - Current Surgical Therapy 14e

• Resectable: no vascular contact, no distant mets
• Borderline resectable: <180° contact with SMA/CA, short segment SMV/PV involvement
• Unresectable: >180° SMA/celiac encasement, solid aortic contact, distant metastases

2. Pancreatic Neuroendocrine Tumors (pNETs)

CYSTIC TUMORS

Quick Memory Table

3. Serous Cystadenoma (SCA) - Benign

• Accounts for 33% of pancreatic cysts; almost universally benign
• CT/MRI: classic "honeycomb" or microcystic pattern (many tiny cysts <2 cm each) with a central stellate scar and sunburst calcification
• Fluid: very low CEA (<5 ng/mL) and low amylase - this is diagnostic
• Associated with Von Hippel-Lindau syndrome (lifetime risk ~40%)

SCA: (A) T2 MRI - 8.5-cm multiloculated pancreatic head cyst; (B) gross honeycombing pattern; (C) bland cuboidal epithelium. - Current Surgical Therapy 14e

4. Mucinous Cystic Neoplasm (MCN) - Premalignant

• 25% of pancreatic cysts; almost exclusively perimenopausal females
• Located in body/tail
• CT/MRI: well-encapsulated, unilocular or multilocular cyst; does NOT communicate with pancreatic duct (important!)
• Elevated CEA in cyst fluid; elevated CEA + low amylase = MCN
• Malignancy risk: 5-15%; red flags = mural nodule, solid component, calcifications, wall thickening
• Path hallmark: ovarian-type stroma underneath the epithelium (required for diagnosis)

5. IPMN (Intraductal Papillary Mucinous Neoplasm)

• Key test: MRCP - shows communication between cyst and pancreatic duct (pathognomonic for IPMN vs. MCN)
• Worrisome features (Fukuoka): mural nodule, thickened/enhancing walls, PD 5-9 mm, abrupt PD caliber change
• High-risk stigmata: obstructive jaundice, enhancing mural nodule >5 mm, PD ≥10 mm - resect

6. Solid Pseudopapillary Neoplasm (SPN) - Low Malignant Potential

• Young females (~20s-30s); rare (5% of resected cysts; 1% of all pancreatic tumors)
• CT: mixed solid + cystic mass; hypoenhancing; often hemorrhagic with fluid-fluid levels; well-circumscribed
• MRI: heterogeneous T1/T2 signal due to hemorrhage; fibrous capsule
• Pathognomonic: "floating debris" from internal hemorrhage and necrosis
• WNT/beta-catenin pathway mutations (90%)
• Management: resection is usually curative; ~4.4% recurrence rate

SPN: (A) CT - 2.6-cm hypoenhancing mixed solid/cystic mass in pancreatic body; (D) pseudopapillary cell pattern on histology. - Current Surgical Therapy 14e

Rare Solid Tumors (Know for Completeness)

The "Radiology First Look" Decision Tree

Is it CYSTIC or SOLID?
│
├── SOLID
│   └── Is it HYPERVASCULAR on arterial phase?
│       ├── YES → pNET (also consider RCC met)
│       └── NO (hypodense) → PDAC (most likely)
│
└── CYSTIC
    ├── Microcystic/honeycomb → SCA (benign, observe)
    ├── Macrocystic, body/tail, no duct comm., F only → MCN (resect all)
    ├── Communicates with pancreatic duct (MRCP) → IPMN
    │       └── Main duct dilated? → High risk (resect)
    │       └── Branch-duct? → Fukuoka criteria
    └── Mixed solid/cystic, young woman → SPN (resect)

Key Imaging Protocols

• Pancreatic protocol CT: Non-contrast + arterial phase (35-40 s) + portal venous phase (70 s) + sometimes delayed. Arterial phase is key for hypervascular tumors (pNET) and for vascular involvement assessment
• MRI/MRCP: Best for cystic lesions, duct communication, and small tumors missed on CT
• EUS + FNA: For cyst fluid analysis (CEA, amylase, cytology) when CT/MRI are equivocal