Surgical Pathology Criteria

Traditional Serrated Adenoma

Differential Diagnosis

Traditional Serrated Adenoma Sessile Serrated Polyp / Adenoma
Cytologic dysplasia throughout Cytologic dysplasia, if present, is a focal lesion
Multiple short crypts, right angled, not reaching the muscularis mucosae Basal dilation and flattening, boot or inverted T shaped, but overall, crypts are vertically arranged and span entire thickness of mucosa
Serration predominantly due to multiple adjacent ectopic crypts Serration predominantly due to exaggerated apical cytoplasm
Proliferation (Ki67) largely restricted to ectopic crypts Patches of proliferation can be seen at all levels
Predominantly polypoid and left sided Sessile and predominantly right sided

 

Traditional Serrated Adenoma Colorectal Tubular Adenoma
Serrated architecture Lacks prominent serration
Complex buds (ectopic crypts) all communicate with lumen Complex glands may not always communicate with surface
CK20 restricted to luminal surfaces CK20 staining random

 

Filiform Variant of Traditional Serrated Adenoma Villous Adenoma
Villi lined by complex serrations Villi lined by relatively uniform columnar cells
Frequent edematous bulbous ends on villi Villi typically pointed

 

Traditional Serrated Adenoma Hyperplastic Polyp
Cytologic dysplasia throughout Lacks cytologic dysplasia
Typically complex architecture Crypts are vertically arranged and not complex
Multiple ectopic crypt foci (short disoriented crypts not reaching the muscularis mucosae) Crypts each span from lumen to muscularis mucosae

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