Table 1 Histologic and molecular features of serrated polyps
Histologic features | Molecular features | ||||||
|---|---|---|---|---|---|---|---|
Type | Crypt architecture | Proliferation zone | Cytologic features | Mucin type | BRAF mutation | KRAS mutation | CpG island methylation |
Microvesicular hyperplastic polyp | Funnel-shaped crypts with serrations limited to upper two-thirds | Located uniformly in the basal portion of crypts | Small basally located nuclei, no dysplasia | Mixed Micro-vesicular and Goblet cell | 70–80% | 0% | + |
Goblet cell hyperplastic polyp | Elongated crypts that resemble enlarged normal crypts; Little to no serrations | Located uniformly in the basal portion of crypts | Small basally located nuclei, no dysplasia | Goblet cell only | 0% | 50% | − |
Sessile serrated polyp | Horizontal growth along the muscularis mucosae, dilation (often asymmetric) of the crypt base (basal third of the crypt), and/or serrations extending into the crypt base | Proliferation may be abnormally located away from the crypt base, variable from crypt to crypt | Small basally located nuclei with occasional larger nuclei with inconspicuous nucleoli, no dysplasia | Mixed Micro-vesicular and Goblet cell | >90% | 0–5% | ++ |
Sessile serrated polyp with dysplasia | As for sessile serrated polyp | As for sessile serrated polyp with more proliferation in dysplastic component | Varied morphologic appearance to dysplastic component | Varied type | >90% | 0% | +++ |
Traditional serrated adenoma | Slit-like serrations, often ectopic crypt foci | Present within ectopic crypt foci and crypt base | Elongated pencillate nuclei with nuclear stratification and cytoplasmic eosinophilia; may develop overt (conventional or serrated) dysplasia | Occasional scattered goblet cells; rare goblet cell variant has been described | 20–40% | 50–70% | BRAF mutated ++ |
KRAS mutated + | |||||||
Serrated adenoma-unclassified | Varied | Varied | Unequivocal dysplasia must be present | Varied | Uncertain | Uncertain | Uncertain |
