Surgical Pathology Criteria

Colorectal Adenoma with Benign Misplacement of Glands / Pseudoinvasion

Differential Diagnosis

Colorectal Adenoma Containing Invasive Adenocarcinoma Colorectal Adenoma with Benign Misplacement of Glands / Pseudoinvasion
Usually significant architectural and/or cytologic atypia Usually lacks significant architectural and/or cytologic atypia (high grade dysplasia may be misplaced occasionally but is typically accompanied by bland adenoma tissue)
Desmoplastic stroma Inflammatory or fibrotic stroma
Infiltrates through muscularis mucosae Frequently demonstrable continuity with surface through a gap in the muscularis mucosae
Hemosiderin restricted to head of polyp Hemosiderin common in stalk stroma
Glands not accompanied by lamina propria Glands may be accompanied by lamina propria
Usually infiltrative, non-circumscribed Frequently circumscribed
May occur throughout the colorectum Virtually restricted to left colon
Collagen type IV weak, discontinuous Collagen type IV strong, continuous around epithelial nests
E cadherin markedly decreased staining compared to overlying adenoma E cadherin same intensity as overlying adenoma (high grade dysplasia may show decrease)

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