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Sessile polyps have a shorter pathway for migration of invasive cells from the tumor into submucosal and more distant structures, and they are also more difficult to remove and ascertain. Sessile polyps larger than 2 cm usually contain villous features, have a higher malignant potential, and tend to recur following colonoscopic polypectomy.
A sessile serrated lesion (SSL) is a premalignant flat (or sessile) lesion of the colon, predominantly seen in the cecum and ascending colon. SSLs are thought to lead to colorectal cancer through the (alternate) serrated pathway. [1] [2] This differs from most colorectal cancer, which arises from mutations starting with inactivation of the APC ...
Traditional serrated adenoma seen under microscopy with H&E stain, showing serrated crypts. SPS may occur with one of two phenotypes: distal or proximal. [6] The distal phenotype may demonstrate numerous small polyps in the distal colon and rectum, whereas the proximal phenotype may be characterized by relatively fewer, but larger polyps in the proximal colon (cecum, ascending colon, etc.). [6]
The pathophysiology of precancerous lesions is thought to be similar to that of cancer, and also varies depending on the disease site and type of lesion. [12] It is thought that cancer is always preceded by a clinically silent premalignant phase during which many oncogenic genetic and epigenetic alterations accumulate before it is truly malignant.
Research supports that compression of tumor vessels by surrounding tumor cells results in mechanical tension and changes in blood flow. [8] It has been suggested that these flow-mediated changes cause abnormal expression of transcription factors which promotes aberrant endothelial morphology, size, and differentiation.
Risk of containing malignant cells Histopathology definition Tubular adenoma 2% at 1.5 cm [4] Over 75% of volume has tubular appearance. [5] Tubulovillous adenoma 20% to 25% [6] 25–75% villous [5] Villous adenoma 15% [7] to 40% [6] Over 75% villous [5] Sessile serrated adenoma (SSA) [8] Basal dilation of the crypts; Basal crypt serration
A vascular tumor is a vascular anomaly where a tumor forms from cells that make blood or lymph vessels; a soft tissue growth that can be either benign or malignant. [1] Examples of vascular tumors include hemangiomas, hemangioendotheliomas, Kaposi's sarcomas, angiosarcomas, and hemangioblastomas. An angioma refers to any type of benign vascular ...
For example, adenomatous polyps in the colon may be pedunculated (lobular head with a long slender stalk) or sessile (broad base). The adenomatous proliferation is characterized by different degrees of cell dysplasia ( atypia or loss of normal differentiation of epithelium) irregular cells with hyperchromatic nuclei, stratified or ...