anus


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  • Normal

    • anal canal zones
      • colorectal zone
      • transition zone
        • anal columns
        • anal sinuses
        • anal transitional epithelium
          • colorectal mucosa
          • simple columnar
          • urothelium like
          • nonkeratinizing squamous
          • anal glands +/- goblet cell metaplasia
      • dentate line
      • squamous zone
        • nonkeratinized squamous
        • no skin appendages
        • anal valve
    • perianal skin
      • keratinized squamous
      • has skin appendages
      • apocrine glands
      • eccrine glands
      • anogenital sweat glands

  • Non-neoplastic

  • WHO neoplasms

    • AIN
    • Bowen disease
    • perianal squamous intraepithelial neoplasia
    • Paget disease
    • carcinoma
      • SCC
      • verrucous carcinoma
      • undifferentiated carcinoma
      • adenocarcinoma
      • mucinous adenocarcinoma
    • neuroendocrine neoplasm
      • carcinoid
      • atypical carcinoid
      • small cell carcinoma
      • large cell neuroendocrine carcinoma
      • mixed adenoneuroendocrine carcinoma
    • mesenchymal
    • metastasis

  • TNM (useful for grossing)

    • Tis: Bowen disease, HSIL, AIN2-3
    • T1: size <= 2 cm
    • T2: size <= 5 cm
    • T3: size > 5 cm
    • T4: adjacent organ invasion (vagina, urethra, bladder)
      • does not include perianal skin, rectal wall, sphincter or soft tissue
    • N1: perirectal nodes
    • N2: unilateral internal iliac or inguinal nodes
    • N3: bilateral N2, or both perirectal and inguinal nodes

  • Staging

    • 0: Tis
    • I: T1
    • II: T2-3
    • IIIA: T4 N0 or T1-3 N1
    • IIIB: T4 N1 or N2-3
    • IV: M1
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