Classification of Tumors of Colon and Rectum

Tumors of colon and rectum may be classified, based on histology, into:

1.    Epithelial tumors:

a.    Adenoma:
i.    Tubular
ii.   Villous
iii.  Tubulovillous
iv.  Serrated

b.    Intraepithelial neoplasia (dysplasia) associated with chronic inflammatory diseases
i.    Low-grade glandular intraepithelial neoplasia
ii.    High-grade glandular intraepithelial neoplasia

c.    Carcinoma
i.     Adenocarcinoma
ii.    Mucinous carcinoma
iii.   Signet-ring carcinoma
iv.   Small cell carcinoma
v.    Squamous cell carcinoma
vi.   Adenosquamous carcinoma
vii.  Medullary carcinoma
viii. Undifferentiated carcinoma

d.    Carcinoid tumor (Well differentiated endocrine neoplasia)
i.    EC cells, serotonin producing neoplasm
ii.    L-cell, glucagonlike peptide and PP/PYY producing tumour
iii.    Others

e.    Mixed carcinoid-adenocarcinoma

f.    Others

2.    Non-Epithelial tumors

a.    Lipoma
b.    Leiomyoma
c.    Gastrointestinal stromal tumour
d.    Leiomyosarcoma
e.    Angiosarcoma
f.    Kaposi sarcoma
g.    Malignanat melanoma
h.    Others
i.    Malignant Lymphomas:

• Marginal zone B-cell lymphoma of MALT type
• Mantle cell lymphoma
• Diffuse large B-cell lymphoma
• Burkitt lymphoma
• Burkitt-like/atypical Burkitt lymphoma
• Others

3.    Secondary Tumors
4.    Polyps:

a.    Hyperplastic polyps (metaplastic)
b.    Peutz-Jeghers
c.    Juvenile polyps