Exclusions: adenomatous polyp and carcinoma
Differential diagnosis of histologic atypia:
(1) reparative atypia
(2) indeterminate for dysplasia
(3) low grade dysplasia
(4) high grade dysplasia
Histologic zones of the colonic crypts for describing immunostaining:
(1) basal third (basal zone)
(2) middle third (mid zone)
(3) upper third (top zone)
Immunostaining may also be seen in the surface epithelium.
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Description of p53 Staining
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Intensity Term
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only detected with a 10x objective
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weak
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intermediate
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moderate
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comparable to positive control using a colon carcinoma
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strong
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Rules:
(1) Ki67 restricted to the basal zone of the crypts excludes dysplasia (but may include indefinite for dysplasia).
(2) Strong p53 staining indicates dysplasia (but was seen in only 11 of 36 patients with low or high grade dysplasia). It exclude regenerative atypia.
(3) Restriction of Ki67 and p53 staining to the basal and mid zones excludes high grade dysplasia (but includes most patients with low grade dysplasia).
Additional observations:
(1) 8 of 36 patients with low or high grade dysplasia had negative staining for p53.
(2) 2 of 22 patients with reparative atypia had p53 staining of the top zone and/or surface epithelium.
(3) 7 of 22 patients with reparative atypia had Ki67 staining of the top zone and/or surface epithelium.
