Pancreas
The pancreas hangs-out in the upper abdomen. It occasionally is afflicited by cancers, the most common of which is very fatal.
Normal anatomy
Divided into three portions: head, body & tail:
- Head:
- Includes unicate process.
- Extend to superior mesenteric vein (by definition).
- Body:
- Superior mesenteric vein to left edge of aorta (by definition).
- Tail:
- Remainder of pancreas.
Pancreatic surgeries
Common pancreatic surgeries include:
- Whipple (includes duodenum).
- Distal pancreatectomy.
- Removal of tail +/- body.
- Total pancreatectomy.
- Often with splenectomy.
General classification of pancreatic tumours
- Metstatses.
- Most common = renal cell carcinoma.
- Primary.
- Endocrine.
- Usually small as hormonally active.
- Exocrine.
- Endocrine.
Pancreas neoplasms in a table
Type | Key feature | Subtypes | Image | IHC | Detailed microscopic | Usual location | Other | DDx |
---|---|---|---|---|---|---|---|---|
Serous tumours | cuboidal cells, clear cytoplasm | cystadenoma, borderline t., cystadenocarcinoma | [1], [2] | IHC? | cuboidal cells, clear cytoplasm, central nucleus | body or tail | - | clear cell RCC, oligomucinous mucinous tumours |
Intraductal papillary mucinous tumour (IPMT) |
mucin, no ovarian-like stroma | clear cell variant | Image? | IHC? | papillae, tall columnar mucin-producing cells | head | - | mucious neoplasms (other pancreatic, duodenal) |
Mucinous tumour | mucin, ovarian-like stroma | cystadenoma, borderline t., cystadenocarcinoma | Image? | IHC? | tall columnar mucin-producing cells, ovarian-like stroma | body or tail | - | IPMT, metastatic mucinous tumours |
Solid pseudopapillary tumour |
eosinophilic intracytoplasmic globules | clear cell variant (cytoplasm clear) | [3] | IHC | sheets of cells, focally loosely cohesive, eosinophilic cytoplasm, uniform nuclei with grooves | none | - | ductal adenocarcinoma |
Ductal adenocarcinoma | irregular shaped glands, cytologic atypia | mucinous, spindle cell, mixed ductal-endocrine | [4], [5] | IHC? | glands, sheets, single cells, nuc. atypia, +/-mitoses, +/-necrosis | head | - | ampullary carcinoma, chronic pancreatitis |
Pancreatoblastoma | squamoid nests, whorling | - | Image? | IHC? | squamoid nests of cells, whorling, nested growth, +/-keratinization | none | - | acinar cell carcinoma |
Acinar cell carcinoma | acinar arch. | - | [6] | IHC? | nests or trabeculae, nucleolus, mod. basophilic granular cytoplasm | head (slight predilection) | - | pancreatoblastoma |
Undifferentiated carcinoma with osteoclast-like giant cells | giant cells | - | Image? | IHC? | giant cells, usu. with AIS or inv. ductal adenocarcinoma | head | - | anaplastic carcinoma |
Chronic pancreatitis | fibrosis, loss of acinar tissue | - | [7] | IHC? | loss of acinar tissue with preservation of islets, fibrosis | ? | not a neoplasm, included here as it is in the DDx | ductal adenocarcinoma |
Most important cystic lesions
- Serous.
- Mucinous.
- Ovarian-like stroma.
- Solid pseudopapillay tumours.
- Intraductal papillary mucinous tumour (IPMT).
- No ovarian-like stroma.
Mnemonic SIMS: Serous, IPMT, Mucinous, Solid pseudopapillary tumour.
Mucinous vs. IMPT
IMPT:
- No ovarian-like stroma.
- Usually has total pancreatectomy.
Cystic tumors of pancreas
- Uncommon.
- 10% of cystic lesion (90% pseudocyst).
- Diagnostic difficulties (hard to differentiate pseudocyst & cyst).
Note:
- Pseudocysts: not real cysts... as no lining epithelium.
Cystic tumours
General
- 50% incidental finding.
- Vague Sx.
- Abdo mass.
- Wt loss.
- Jaundice.
Note:
- Usually diagnosed by imaging (CT/MRI, ERCP, Endoscopic ultrasound).
Serous cystic tumours
General
- Cell of origin: intralobular duct cells (ductular cells).
- Glycogen rich - but do not produce mucin.
Subclassication
- Serous microcystic adenoma.
- Many small cysts.
- Serous oligocystic adenoma.
- Large cysts.
- Serous adenocarcinoma - rare.[1]
Note:
- If one mucin +ve cell, tumour = a mucinous tumour.
Characteristics of serous microcystic adenoma
- 1-2% of all exocrine pancratic tumours.
- Female>Male.
- Mean age 66 years.
- Truly benign with no malignant potenial.
- May not require surgical resection.
- May be part of von Hippel-Lindau.
- 50-70% occur in the body and tail.
- Average size 11 cm.
Radiology
- Honey comb appearance.
- "Coin lesion" - well demarcated border.
- May have central scar.
Gross
- Bosulated surface.
- Lobulated.
- No (macroscopic) cysts apparent on gross.
Microscopic
Features:
- Cuboidal cells.
- Glycogen rich.
DDx
- Renal cell carcinoma.
- Lympangioma.
- Hemangiomas.
- Oligocystic mucinous cystic tumors and pseudocysts.
- Have mucin; PAS-D could be used to demonstrate its presence.
Notes:
- Serous adenoma my coexist with aggressive tumours.
Mucinous cystic tumours
- Gastro-entero-pancreatic cell differentiation with hypercellular ovarian-type stroma.
- Stroma --> cellular.
- 2-2.5% of all exocrine pancreatic tumours.
- Almost exclusively in women.
- Mean age - 49 years.
- >80% in body and tail.
- Average size ~10 cm.
Note:
- Looks different than serous tumour.
Subclassification
- Sucinous cystadenoma.
- Borderline mucinous cystic tumour.
- Mucinous cystadenocarcinoma.
Borderline vs. Carcinoma
- Few mitoses in borderline.
Radiology
- Mucinous tumours: multilocular.
- Generally larger than serous.
- Often partially solid and cystic.
- Often calcified.
- Calcification rare in serous.
- Usually tail & body.
Microscopic
Mucinous cystadenoma
Features:[2]
- Simple tall columnar epithelium with large mucin vacuole on apical aspect.
- "Ovarian-type stroma" under epithelium.
- Ovarin-type stroma: high density of small (non-wavy) spindle cells with eosinophilic cytoplasm.
Image: Mucinous cystadenoma - ovary (uchc.edu).
Notes:
- Appearance similar to mucinous cystadenoma in the ovary.
- Mucin stains +ve (intracytoplasmic).
Borderline mucinous cystic tumour
Features:
- May have finger like projections.
- Pseudostratification of epithelium.
Notes:
- Surgery does not change based on diagnosis on frozen section.
- Only question is "Is the margin clear?".
- Borderline tumours are rare.
Carcinoma
- Cells floating in mucin.
Mucinous tumour vs. pseudocyst
mucinous t pseudocyst amylase & lipase low high viscosity high low CEA, CA124 high low
Prognosis:
- Benign looking tumours have the potential to transform into carcinoma.
- No report of assoc. pseudomyxoma peritonei.
- US boards question -- it is an exception ... others one cause it.
- Prognosis of m. cystadenocarcinoma is slightly better than that of ductal adenocarcinoma.
Intraductal papillary mucinous tumour
General
- Often abbreviated IPMT.
- Papillomatous growth pattern.
- Morphologically and biologically distinct from ductal adenocarcinoma, mucinous cystic tumour and ductal papillary hyperplasia.
Epidemiology
- 1% of all exocrine pancreatic tumours.
- More common in males.
- Mean age at presentation 62 years.
- 60-80% occur in the head of the pancreas.
- Average size 4 cm.
Khalifa's theory:
- Nothing but dilation of pancreatic duct + hypersecretion.
Adenoma-carcinoma sequence
- Hyperplasia.
- Adenomatous hyperplasia.
- Carcinoma in situ.
- Invasive carcinoma.
Note: K-ras oncogene mutation associated - seen in all stages of the sequence.
Gross
- May be patchy/multifocal.
Microscopic
Features
- Cell enlargement.
- Incr. NC ratio.
- Nuclear crowding and pleomorphism.
- Papillary tufting.
- Mitotic activity.
- Increased mucin production.
Classification IMPT
- Adenoma.
- Borderline mucinous tumour.
- Carcinoma.
NB1
- No ovarian like stroma.
- In duct.
NB2
- Usually not jaundiced... as no obstruction.
- Often diabetes... as pancreas is destroyed.
Gross
- Multiple cystic spaces.
Micro
- Some places -- fronds of benign looking mucin producing epithelium.
- No ovarian type stroma underneath.
NB
- If no viable cells in the mucin then not cancer.
- Mucin under pressure can disect through the tissue.
- Borderline tumours are rare.
Pitfalls
- Since it is multifocal may involve large segment of the ductal system.
- Patients often get a total pancreatectomy.
- If intralobular dilated ducts... carcinoma.
- Hard to get a negative margin.
Prognosis: favourable.
NB - any margin with mucin cells -- badness!!!
- Dilated = mucin producing ducts (???).
- DDx: PAN-IN1.
- Needs a totally pancreatectomy.
- DDx: PAN-IN1.
Solid pseudopapillary tumour
General
- Obscure cell of origin.
- Considered low grade, i.e. prognosis is usually good.
Epidemiology
Features:[3]
- Usually females (M:F=1:9).
- Mean age of presentation third decade (20s).
Management
May be followed radiologically.
Microscopic
Features:[4]
- Solid sheets of cells, focally dyscohesive.
- Eosinophilic cytoplasm.
- Occasionally clear cytoplasm.[5]
- Focal eosinophilic (intracytoplasmic) globules - key feature.
- Uniform nuclei with occasional nuclear grooves.
- +/-Necrosis - creating spaces/cavities.
Image: Solid pseudopapillary tumour (bmj.com).
DDx
- Pseudocyst.
- Cystadenoma.
- Cystadenocarcinoma.
Carcinomas
- Usually head of pancreas.
DDx:
- Mucinous tumour (may be misdiagnosed as this).
- Serous tumour (microcystic).
Gross
- Necrosis.
- Capsule.
- Hemorrhage.
Microscopic
Features:
- Solid.
- Necrosis.
- Myxoid degeneration.
- Cells around vessels.
- Nuclei.
- Bland.
- Small nuclei.
- Little pleomorphism.
- Sometimes coffee-bean appearance.
- Cytoplasm - granular, abundant.
- Quasi endocrine look.
- May stain positive for endocrine markers.
Cystic tumours
- Diagnosed by imaging/with help of images.
Stains
- PAS-D
Prognosis: very favourable (mostly benign).
Cystic tumours of the pancreas
Khalifa's table of cystic tumours:
Sex | Age (years) | Usual site | Typical size (cm) | |
Microcystic | female | 66 | B&T | 11 |
Mucinous | female | 49 | B&T | 10 |
IPMT | male | 62 | H | 4 |
Pseudopapillary | female | 35 | any | 7.5 |
References
- ↑ MK. Half-day.
- ↑ GLP P.489.
- ↑ GLP P.493.
- ↑ GLP P.493-5.
- ↑ Serra S, Chetty R (November 2008). "Revision 2: an immunohistochemical approach and evaluation of solid pseudopapillary tumour of the pancreas". J. Clin. Pathol. 61 (11): 1153–9. doi:10.1136/jcp.2008.057828. PMID 18708424. http://jcp.bmj.com/content/61/11/1153.