Anus

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The anus occasionally shows-up on the pathologists desk. It sometimes comes with the rectum and colon, as an abdominoperoneal resection (APR).

Benign disease

Perianal abscess

General

  • Common.

Microscopic

Features:

  • Abscess - (extravascular) cluster of neutrophils - key feature.
  • Reactive epithelium.
  • Reactive stromal cells.

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PERIANAL MASS, EXCISION: 
- PERIANAL ABSCESS. 
- REACTIVE SQUAMOUS EPITHELIUM WITH PARAKERTOSIS AND ULCERATION. 
- ABUNDANT COCCI ORGANISMS IN CLUSTERS. 
- NEGATIVE FOR MALIGNANCY.

Hidradenoma papilliferum

See Hidradenoma papilliferum.

Hemorrhoids

General

  • Benign.

Clinical features:[1]

  • Bright red blood per rectum (BRBPR).
  • Pain.
  • Itching.
  • Prolapse.

Gross

Features:[2]

  • Grey mucosa.
  • Pale or purple stroma.

Microscopic

Features:[2]

  • Polypoid lesion - epithelium on three sides:
    • Large dilated veins and thick-walled vessels +/- fibrin thrombi - key feature.
    • Edema.
    • Squamous epithelium +/- keratinization or columnar epithelium.

DDx:

Image:

Anal neoplasia

Immunosuppressed individuals and homosexuals have a higher risk of anal intraepithelial neoplasia (AIN) and anal cancer.[3][4]

Anal intraepithelial neoplasia

  • Abbreviated AIN.

General

Grading

AIN is graded much like cervical intraepithelial neoplasia:

  • High-grade anal intraepithelial neoplasia (HGAIN).
  • Low-grade anal intraepithelial neoplasia (LGAIN).

Anal cancer

Anal gland adenocarcinoma

  • Abbreviation AGA.
  • AKA anal adenocarcinoma.

General

  • Rare.

Risk factors:[5]

Microscopic

Features:[6]

  • Adenocarcinoma within the anal wall but not within the mucosa, i.e. extramucosal and intramural - key feature.
    • The tumour lies beneath the squamous mucosa/rectal mucosa.

DDx:

Image:

IHC

Features:[6]

  • CK7 +ve.
  • CK20 -ve.
  • CDX2 -ve.
  • p63 -ve.
  • PSA -ve.

See also

References

  1. Cazemier, M.; Felt-Bersma, RJ.; Cuesta, MA.; Mulder, CJ. (Jan 2007). "Elastic band ligation of hemorrhoids: flexible gastroscope or rigid proctoscope?". World J Gastroenterol 13 (4): 585-7. PMID 17278225.
  2. 2.0 2.1 Iacobuzio-Donahue, Christine A.; Montgomery, Elizabeth A. (2005). Gastrointestinal and Liver Pathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Churchill Livingstone. pp. 401. ISBN 978-0443066573.
  3. Park IU, Palefsky JM (March 2010). "Evaluation and Management of Anal Intraepithelial Neoplasia in HIV-Negative and HIV-Positive Men Who Have Sex with Men". Curr Infect Dis Rep 12 (2): 126–133. doi:10.1007/s11908-010-0090-7. PMC 2860554. PMID 20461117. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2860554/.
  4. Czoski-Murray C, Karnon J, Jones R, Smith K, Kinghorn G (November 2010). "Cost-effectiveness of screening high-risk HIV-positive men who have sex with men (MSM) and HIV-positive women for anal cancer". Health Technol Assess 14 (53): 1–131. doi:10.3310/hta14530. PMID 21083999.
  5. Tarazi, R.; Nelson, RL.. "Anal adenocarcinoma: a comprehensive review.". Semin Surg Oncol 10 (3): 235-40. PMID 8085101.
  6. 6.0 6.1 6.2 Warsch, S.; Bayraktar, UD.; Wen, BC.; Zeitouni, J.; Marchetti, F.; Rocha-Lima, CM.; Montero, AJ. (Mar 2012). "Successful treatment of anal gland adenocarcinoma with combined modality therapy.". Gastrointest Cancer Res 5 (2): 64-6. PMID 22690260.