Pseudoinvasion in colorectal adenomatous polyps

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

Pseudoinvasion and epithelial misplacement redirect to this article.

General

  • Mimic of invasion.
  • Pedunculated polyps.[1]
  • Left-sided lesions, esp. sigmoid colon.[2]

Microscopic

Features - classic:[3]

  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:

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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

References

  1. ↑ Byun, TJ.; Han, DS.; Ahn, SB.; Cho, HS.; Eun, CS.; Jeon, YC.; Sohn, JH.; Oh, YH. (Jun 2009). "Pseudoinvasion in an adenomatous polyp of the colon mimicking invasive colon cancer.". Gut Liver 3 (2): 130-3. doi:10.5009/gnl.2009.3.2.130. PMC PMC2852693. PMID 20431736. https://www.ncbi.nlm.nih.gov/pmc/articles/PMCPMC2852693/.
  2. ↑ Odze, Robert D.; Goldblum, John R. (2009). Surgical pathology of the GI tract, liver, biliary tract and pancreas (2nd ed.). Saunders. pp. 512. ISBN 978-1416040590.
  3. ↑ Muto, T.; Bussey, HJ.; Morson, BC. (Jan 1973). "Pseudo-carcinomatous invasion in adenomatous polyps of the colon and rectum.". J Clin Pathol 26 (1): 25-31. PMC 477644. PMID 4540378. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC477644/.
  4. ↑ Gonzalez, RS.; Cates, JM.; Washington, MK.; Beauchamp, RD.; Coffey, RJ.; Shi, C. (Jan 2016). "Adenoma-like adenocarcinoma: a subtype of colorectal carcinoma with good prognosis, deceptive appearance on biopsy and frequent KRAS mutation.". Histopathology 68 (2): 183-90. doi:10.1111/his.12725. PMID 25913616.
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