Invisible colonic dysplasia

Invisible colonic dysplasia is colonic dysplasia that is not seen on endoscopy.

General

• The reason for random biopsies in inflammatory bowel disease.
• Relatively uncommon - one series of ulcerative colitis patients estimated ~12% of lesions are "invisible".

Gross

• Not visible - definitional.

Microscopic

Features:

1. Nuclear changes at the surface of the mucosa - key feature.
   • Size and shape or size change:
     • Cigar-shaped (elongated) nucleus (usu. length:width > 3:1) with nuclear hyperchromasia (more blue).
     • Large round nuclei +/- vesicular appearance (clearing) -- nuclei have white space.
   • Nuclear crowding/pseudostratification - important.
   • +/-Loss of nuclear polarity (nuclei no longer on basement membrane).
2. Loss/decrease of goblet cells (common).
3. Cytoplasmic hyperchromasia.

Notes:

• Nuclear changes deep to the surface are non-neoplastic if normal appearing mucosa (with small round nuclei) is superficial to it; mucosa that is more blue and atypical deep and less blue without nuclear atypia at the surface is said to be "maturing".
  • Classically, adenomatous polyps have "reverse maturation":
    • The surface is more hyperchromatic (more blue).
    • The base is more mature (more globlet cells, no nuclear changes -- less blue).
• Ampullary adenomas often have less prominent pseudostratification and fine chromatin.

DDx:

• Reactive changes due to inflammation.
• Invasive adenocarcinoma.

See also

• DALM.