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Squamous Carcinoma of the Colon and Rectum

Definition

  • Squamous carcinoma arising in the colon and rectum

Covered separately

Diagnostic Criteria

  • Usual appearance of squamous carcinoma
    • Lacks the frequent variety of patterns of anal squamous carcinoma
  • Must not involve anal squamous mucosa
    • Some require location >5 cm above dentate line
    • Anal squamous carcinomas frequently extend into the rectum
  • Must not be associated with a fistula
  • Must not form any glands
  • Must not have history of squamous carcinoma elsewhere
  • May be associated with inflammatory intestinal disorders

Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting/updates : 1/31/10, 11/12/11

Supplemental studies

Immunohistology

  • Staining for p16 is a useful surrogate for the presence of high risk HPV
    • Positive in 3 of 3 cases of rectal SCC in a recent study (Kong 2006)
      • Positive reaction requires strong, band-like staining
      • Both nucleus and cytoplasm usually stained
  • Phenotype differs from anal squamous carcinoma and rectal adenocarcinoma:
  •   CAM5.4 AE1&3 HMW keratin 34BE12 CK7 CK20
    Rectal SCC 80% 100% 100% 20% 0%
    Anal SCC 0% 100% 100% Focal 0%
    Rectal Adenoca 100% 100% Rare cells Focal 100%
    Nahas 2007

Genetic Analysis

  • High risk human papilloma virus (HPV) demonstrated in 3 of 3 cases in a recent study (Kong 2006)

Differential Diagnosis

  Colorectal Squamous Carcinoma Colorectal Adenosquamous Carcinoma Colorectal Adenocarcinoma with Squamous Metaplasia
Squamous component Malignant Malignant Benign
Glandular component Absent Malignant Malignant
Both components must be more than focal
Squamous Carcinoma of the Anus Colorectal Squamous Carcinoma
Must involve anal canal Must not involve the anal squamous mucosa
Some require that colorectal SCC be at least 5-7 cm from the anus
  • Metastatic squamous carcinoma from other sites must be ruled out clinically

Clinical

  • Historically poor prognosis with surgical treatment
  • Therapy similar to anal squamous carcinoma
    • Therapy centered on radiation and chemotherapy followed by local excision, if there is a residual lesion, appears to give good results
    • One recent series of rectal SCC with 100% survival (Nahas 2007)

Grading / Staging

Grading

  • There is no accepted grading scheme

Staging

  • Colorectal TNM applies to all kinds of carcinoma
    • Some use TNM staging for anal squamous carcinoma instead

Bibliography

  • Bosman FT, Carneiro F, Hruban RH, Thiese ND (Eds). WHO Classifiication of Tumors of the Digestive System, IARC, Lyon 2010
  • Kong CS, Welton ML, Longacre TA. Role of human papilloma virus in squamous cell metaplasia-dysplasia-carcinoma of the rectum. Am J Surg Pathol. 2007 Jun;31(6):919-25.
  • Nahas CS, Shia J, Joseph R, Schrag D, Minsky BD, Weiser MR, Guillem JG, Paty PB, Klimstra DS, Tang LH, Wong WD, Temple LK. Squamous-cell carcinoma of the rectum: a rare but curable tumor. Dis Colon Rectum. 2007 Sep;50(9):1393-400.
  • Frizelle FA, Hobday KS, Batts KP, Nelson H. Adenosquamous and squamous carcinoma of the colon and upper rectum: a clinical and histopathologic study. Dis Colon Rectum. 2001 Mar;44(3):341-6.
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