Colon dysplasia describes abnormal changes in the cells lining the colon, which is the large intestine. These changes are not cancerous but indicate a higher chance of developing colorectal cancer over time. Detecting and addressing these changes helps prevent cancer progression.
What Colon Dysplasia Is
Colon dysplasia involves changes in the appearance and organization of cells within the inner lining of the large intestine, deviating from normal structure. These changes are considered abnormal growth. Dysplasia is classified into different grades based on how abnormal the cells appear under a microscope.
Low-grade dysplasia, sometimes called mild or moderate, involves less significant cellular changes where the cell architecture remains somewhat organized. The nuclei, which house the cell’s genetic material, show only minor irregularities. In contrast, high-grade dysplasia indicates more pronounced and widespread cellular changes. Cells exhibit greater disorganization, with larger, more irregular, and often darker nuclei, and they tend to divide more rapidly. High-grade dysplasia increases the risk of colorectal cancer if left untreated, requiring careful monitoring.
How Colon Dysplasia Develops
Colon dysplasia frequently develops from polyps, abnormal growths on the colon’s inner lining. Adenomatous polyps are a common type that can progress to cancer. The adenoma-carcinoma sequence describes this transformation from normal colon lining to cancer. Normal colon cells develop into an adenomatous polyp, then acquire dysplastic changes. These dysplastic cells may accumulate further genetic alterations, potentially leading to invasive cancer.
Chronic inflammatory conditions, such as inflammatory bowel disease (IBD), are another factor in the development of colon dysplasia. Long-standing inflammation in the colon can cause genetic and epigenetic changes that lead to the formation of dysplastic cells. In patients with IBD, the risk of dysplasia and colorectal cancer increases with the extent and duration of the disease.
Finding Colon Dysplasia
Colon dysplasia is detected during routine colorectal cancer screenings, with colonoscopy being the primary diagnostic tool. During a colonoscopy, a flexible tube with a camera examines the inside of the colon and rectum to identify abnormal growths or areas. If suspicious areas are found, tissue samples, known as biopsies, are collected through the colonoscope.
These biopsy samples are sent to a laboratory where a pathologist examines them under a microscope. The pathologist diagnoses dysplasia by assessing cellular changes, including cell appearance, organization, and nuclear characteristics. This microscopic examination allows for definitive diagnosis and grading (low-grade or high-grade).
What Happens After Diagnosis
The management strategy for colon dysplasia depends on its grade and whether it is found within a polyp or as a flat lesion. If dysplasia is identified within a polyp, the polyp is removed during colonoscopy (polypectomy). This removal prevents dysplastic cells from potentially progressing to cancer.
For low-grade dysplasia, regular surveillance colonoscopies are often recommended to ensure no new areas develop. If high-grade dysplasia is found, or if there are multiple areas of dysplasia, more frequent follow-up colonoscopies are advised. In some cases, such as with extensive high-grade dysplasia or in inflammatory bowel disease patients, surgical removal of a portion of the colon (bowel resection or colectomy) might be considered.