Pseudoinvasion in colorectal adenomatous polyps

Pseudoinvasion in colorectal adenomatous polyps is a mimic of invasive adenocarcinoma.

General

• Mimic of invasion.
• Pedunculated polyps.
• Left-sided lesions, esp. sigmoid colon.

Microscopic

Features - classic:

1. Dysplastic glands surrounded by lamina propria.
2. Hemosiderin.
3. Lack of desmoplastic reaction.

• +/-Cystic spaces with rounded contours without cells floating in them.

Memory device (classic features) LDH:

• Lamina propria.
• Desmoplasia lacking.
• Hemosiderin.

DDx:

• Colorectal adenocarcinoma.

Sign out

Note:

• The term pseudoinvasion may be confusing to clinicians.

COLON POLYP, SIGMOID COLON AT 45 CM, EXCISION:
- TUBULAR ADENOMA.
-- NEGATIVE FOR HIGH-GRADE DYSPLASIA.
- SUBMUCOSA PRESENT, NO EVIDENCE OF INVASION.
- ABUNDANT HEMOSIDERIN-LADEN MACROPHAGES.

Alternate

 POLYP, SIGMOID COLON, EXCISION:
- LARGE TUBULAR ADENOMA.
-- NEGATIVE FOR HIGH-GRADE DYSPLASIA.
- SCANT BENIGN SUBMUCOSA.
- DEEP HEMOSIDERIN-LADEN MACROPHAGES.

See also

• Gastrointestinal tract polyps.