Gastrointestinal cytopathology

Gastrointestinal cytopathology, also known as GI cytology, is a relatively small part of cytopathology.

This article deals only with gastrointestinal cytopathology. An introduction to cytopathology is in the cytopathology article. Histopathology of the gastrointestinal tract is dealt with in gastrointestinal pathology.

Liver

Brief DDx:

• Metastatic adenocarcinoma, usu. colorectal adenocarcinoma.
• Hepatocellular carcinoma.

Others:

• Cholangiocarcinoma - usu. adenocarcinoma NOS, i.e. non-specific.
• Epithelioid hemangioendothelioma.
• Angiomyolipoma.

Normal liver

Cytology

Features:

• Hepatocytes:
  • Abundant cytoplasm
  • central nucleus +/- binucleation.
  • +/-Yellow granular pigment (bile).
• Bile ductules between adjacent cells.

Hepatocellular carcinoma

Main article: Hepatocellular carcinoma

Cytology

Features:

• Architecture - single cells and large clusters:
  • Cohesive clusters of cells (hepatocytes) surrounded by endothelial cells - diagnostic.
  • Capillaries traversing the fragments.
• Cells:
  • Central nucleus +/-prominent nucleoli, +/-nuclear inclusions.
  • +/-Multinucleation.
  • +/-Yellow cytoplasmic pigment (bile).
  • +/-Nuclear atypia.
  • +/-High NC ratio.

Notes:

• Low grade HCC is composed of cytologically normal appearing cells; the arrangement is what is diagnostic of malignancy.
• Fibrolamellar HCC has very large cells.

Images:

• HCC cytology (flickr.com/euthuman).
• HCC cytology (ouhsc.edu).

Cholangiocarcinoma

Main article: Cholangiocarcinoma

Cytology

Features:

• Looks like an adenocarcinoma:
  • Eccentric nuclei, one nucleolus per cell, abundant cytoplasm, nuclear size var. cell-to-cell, irregular nuclear membrane, irregular/uneven chromatin pattern.

Epithelioid hemangioendothelioma

Main article: Epithelioid hemangioendothelioma

General

• Rare.

Cytology

Features:

• Large atypical cells with:
  • Nuclear inclusions
  • Moderate cytoplasm.
  • +/-Multinucleation.

IHC

• Factor VIII +ve.

Common bile duct

Normal:

• Monolayer of small blue cells.

Notes:

• Caution is advised when calling malignancy in the setting of a stent or stones.

Adenocarcinoma

Features:

• Hyperchromasia.
• Pencil-shaped nuclei.
• Nuclear membrane irregularities.

Images:

• Colorectal adenocarcinoma - low mag. (WC).
• Colorectal adenocarcinoma - intermediate mag. (WC).

Stomach

Normal stomach

General

• Important as it may be a contaminant in a pancreatic FNA.

Cytology

Features:

• Bland cells with round nuclei.
• Granular cells with red cytoplasm (on Pap stain) - parietal cells - distinctive.

Note:

• May be difficult to distinguish from pancreas ductal epithelium.

Small bowel

Epithelium:

• Small blue cells.
• Goblet cells - key feature.

Notes:

• May appear to be similar to stomach and pancreatic duct.

Esophagus

• Cytology may be done to look for candida.
  • Report should comment on the presence of candida - if it is seen.

A short DDx:

• Barrett's esophagus.
• Candida.
• HSV.
• GIST.

Pancreas

A short DDx:

• Normal:
  • Duct.
  • Acini.
• Cystic lesions:
  • Serous cystadenoma of the pancreas.
  • IPMN.
  • Mucinous cystadenoma of the pancreas.
  • Solid pseudopapillary neoplasm.
• Others:
  • Ductal carcinoma of the pancreas.
  • Pancreatic neuroendocrine tumour.

Normal pancreas

Cytology

Features - duct:

• 2-D sheet of cells - equally spaced.
• Moderate-to-abundant cytoplasm.

Features - acini:

• Clustered cells +/- nuclear overlap.
• Round bland nuclei.
  • Small nucleoli.
• Moderate cytoplasm.

Mucinous tumours

Features:

• Mucin.

Image:

• Mucin (ouhsc.edu).

Solid pseudopapillary neoplasm

Main article: Solid pseudopapillary neoplasm

Cytology

Features:

• Small cells with:
  • Scant cytoplasm.
  • +/-Nuclear grooves.
• Papillary formations.

IHC

• PR +ve.
• Beta-catenin +ve.
• CD10 +ve.

Others:

• Chromogranin A -ve.

Pancreatic neuroendocrine tumour

Main article: Pancreatic neuroendocrine tumour

Cytology

Features:

• Round nuclei with granular chromatin.
  • Moderate nuclear size variation.

IHC

• Chromogranin A +ve.
• Synaptophysin +ve.

See also

• Cytopathology.
• Gastrointestinal pathology.