Difference between revisions of "Pancreas"

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(→‎Ductual adenoarcinomas: +PanIN section)
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*Cystadenoma.
*Cystadenoma.
*Cystadenocarcinoma.
*Cystadenocarcinoma.
==Pancreatic intraepithelial neoplasia (PanIN)==
*PanIN is thought to be the precursor lesion for pancreatic carcinoma.<ref>PBoD P.949.</ref>
===Overview===
Putative preneoplasm-neoplasm-carcinoma sequence:
*PanIN1a.
**Not neoplastic, i.e. colonal.
*PanIN1b.
**Not neoplastic, i.e. colonal.
*PanIN2.
**Can be thought of as ''low-grade dysplasia'', e.g. a ''(colonic) tubular adenoma without high-grade dysplasia''.
*PanIN3.
**Can be thought of as ''high-grade dysplasia'', e.g. ''(colonic) villous adenoma''.
===Histomorphology===
Features:<ref>PBoD P.949.</ref>
*PanIN1a - increased amount of cytoplasm.
**Nuclear size & stratification perserved, arch. perserved.
*PanIN1b - increased amount of cytoplasm, folding of epithelium/moderated arch. distortion.
**Nuclear size & stratification perserved.
*PanIN2 - increased cell size, and nuclear enlargement (increased NC ratio), moderate nuclear atypia with loss of (basal) nuclear polarization.
*PanIN3 - marked nuclear atypia with increased NC ratio.
**No invasion identified.
*Pancreatic carcinoma - cytologic features of PanIN3 with definite invasion.
Image: [http://commons.wikimedia.org/wiki/File:Pancreas_neoplasia_carcinoma_sequence.png Normal pancreas, pancreatic intraepithelial neoplasia and pancreatic carcinoma (WC)].


==Ductual adenoarcinomas==
==Ductual adenoarcinomas==

Revision as of 17:12, 29 May 2010

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.

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 [3] 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) [4] 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 [5], [6] IHC? glands, sheets, single cells, nuc. atypia, +/-mitoses, +/-necrosis head arises from the precursor PanIN 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. - [7] 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 - [8] 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.
  • Prognosis: favourable, if caught earlier; not much different than ductal adenocarcinoma if caught later.[3]

Another paper: [4]

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.

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.

Notes:

  • No ovarian like stroma.
  • Tumour in duct.
  • Patient usually not jaundiced... as no obstruction.
  • Often diabetes... as pancreas is destroyed.

Gross

  • Multiple cystic spaces.

Microscopic

Features:

  • Some places -- fronds of benign looking mucin producing epithelium.
  • No ovarian type stroma underneath.

Notes:

  • 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.

NB - any margin with mucin cells -- badness!!!

  • Dilated = mucin producing ducts (???).
    • DDx: PAN-IN1.
      • Needs a totally pancreatectomy.

Solid pseudopapillary tumour

General

  • Obscure cell of origin.
  • Considered low grade, i.e. prognosis is usually good.

Epidemiology

Features:[5]

  • Usually females (M:F=1:9).
  • Mean age of presentation third decade (20s).

Management

May be followed radiologically.

Microscopic

Features:[6]

  • Solid sheets of cells, focally dyscohesive.
  • Eosinophilic cytoplasm.
    • Occasionally clear cytoplasm.[7]
    • 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.

Pancreatic intraepithelial neoplasia (PanIN)

  • PanIN is thought to be the precursor lesion for pancreatic carcinoma.[8]

Overview

Putative preneoplasm-neoplasm-carcinoma sequence:

  • PanIN1a.
    • Not neoplastic, i.e. colonal.
  • PanIN1b.
    • Not neoplastic, i.e. colonal.
  • PanIN2.
    • Can be thought of as low-grade dysplasia, e.g. a (colonic) tubular adenoma without high-grade dysplasia.
  • PanIN3.
    • Can be thought of as high-grade dysplasia, e.g. (colonic) villous adenoma.

Histomorphology

Features:[9]

  • PanIN1a - increased amount of cytoplasm.
    • Nuclear size & stratification perserved, arch. perserved.
  • PanIN1b - increased amount of cytoplasm, folding of epithelium/moderated arch. distortion.
    • Nuclear size & stratification perserved.
  • PanIN2 - increased cell size, and nuclear enlargement (increased NC ratio), moderate nuclear atypia with loss of (basal) nuclear polarization.
  • PanIN3 - marked nuclear atypia with increased NC ratio.
    • No invasion identified.
  • Pancreatic carcinoma - cytologic features of PanIN3 with definite invasion.

Image: Normal pancreas, pancreatic intraepithelial neoplasia and pancreatic carcinoma (WC).

Ductual adenoarcinomas

General

  • Usually in the head ~60%.
    • 15% in the body, 5% tail, 20% diffuse (head, body & tail).[10]
  • Abysmal prognosis.

Microscopic

Features:[11]

  • Often glandular, may be solid.
  • Nuclei.
    • May be bland - little pleomorphism.
    • Often small nuclei.
    • Sometimes coffee-bean appearance.
  • Cytoplasm - granular, abundant.
  • Quasi endocrine look.
    • May stain positive for endocrine markers.

Other features:

  • +/-Necrosis.
  • +/-Myxoid degeneration.
  • +/-Cells around vessels.

Images:

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

External links