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4 slides generated from the cancer page, with a quiz from the open benchmark and speaker notes that cite the sources. Arrow keys move between slides; Print gives one slide per page.
Adenoma-like adenocarcinoma is a form of bowel cancer whose invasive part still looks like a harmless polyp under the microscope, which is why it is often reported as an adenoma on biopsy and only recognised once the bowel is removed. Despite frequently growing deep into the bowel wall, it spreads to lymph nodes less often than ordinary bowel cancer and does better.
What it is. The fifth edition of the World Health Organization classification of digestive tumours added adenoma-like adenocarcinoma as a subtype of colorectal adenocarcinoma (Nagtegaal 2020). The invasive component keeps the low-grade villous or tubulovillous architecture and cytology of an adenoma, with pushing rather than infiltrative invasion and little or no desmoplastic stroma, so material taken at endoscopy does not look malignant.
How it differs from its parent. In a series of 35 such carcinomas, 43 percent had been reported as an adenoma on the preceding biopsy and 60 percent of the resections showed no residual conventional adenoma; despite an advanced T category in 66 percent, only 20 percent had nodal metastases and 15 percent developed distant metastases, and KRAS mutation was frequent (Histopathology 2016). A later review of resected stage I to III colonic adenocarcinomas from one institution classified 91 as adenoma-like, 71 percent of them purely so, and compared them with 251 adenocarcinomas of no special type (Hum Pathol 2021).
| Setting | Approach | Guideline |
|---|---|---|
| Localised disease | Resection with adjuvant chemotherapy decided by stage as for colorectal adenocarcinoma of no special type; the deceptive biopsy appearance means the diagnosis is often made only on the resection specimen. | not mapped |