It was later further studied by Henry Lynch who recognized an autosomal dominant transmission pattern with those affected having relatively early onset of cancer (mean age 44 years), greater occurrence of proximal lesions, mostly mucinous or poorly differentiated adenocarcinoma, greater number of synchronous and metachronous cancer cells, and good outcome after surgical intervention. The Amsterdam Criteria was initially used to define Lynch syndrome before the underlying genetic mechanism had been worked out. The Criteria required that the patient has three family members all first-degree relatives with colorectal cancer that involves at least two generations with at least one affected person being younger than 50 years of age when the diagnosis was made. The Amsterdam Criteria is too restrictive and was later expanded to include cancers of endometrial, ovarian, gastric, pancreatic, small intestinal, ureteral, and renal pelvic origin. The increased risk of cancer seen in patients with by the syndrome is associated with dysfunction of DNA repair mechanism. Molecular biologists have linked the syndrome to specific genes such as hMSH2, hMSH1, hMSH6, and hPMS2. Peutz–Jeghers syndrome
Peutz–Jeghers syndrome is an autosomal dominant syndrome that presents with hamartomatous polyps, which are disorganized growth of tissues of the intestinal tract, and hyperpigmentation of the interlining of the mouth, lips and fingers. The syndrome was first noted in 1896 by Hutchinson, and later separately described by Peutz, and then again in 1940 by Jeghers.
A colorectal polyp is a polyp (fleshy growth) occurring on the lining of the colon or rectum. Untreated colorectal polyps can develop into colorectal cancer.Colorectal polyps are often classified by their behaviour (i.e. benign vs. malignant) or cause (e.g. as a consequence of inflammatory bowel disease). They may be benign (e.g. hyperplastic polyp), pre-malignant (e.g. tubular adenoma) or malignant (e.g. colorectal adenocarcinoma). Signs and symptoms
Colorectal polyps are not usually associated with symptoms. When they occur, symptoms include bloody stools; changes in frequency or consistency of stools (such as a week or more of constipation or diarrhoea); and fatigue arising from blood loss. Anemia arising from iron deficiency can also present due to chronic blood loss, even in the absence of bloody stools. Another symptom may be an increased mucus production especially those involving villous adenomas. Copious production of mucous causes loss of potassium that can occasionally result in symptomatic hypokalemia. Occasionally, if a polyp is big enough to cause a bowel obstruction, there may be nausea, vomiting and severe constipation. Structure
Polyps are either pedunculated (attached to the intestinal wall by a stalk) or sessile (grow directly from the wall). : 1342   In addition to the gross appearance categorization, they are further divided by their histologic appearance as tubular adenoma which are tubular glands, villous adenoma which are long finger like projections on the surface, and tubulovillous adenoma which has features of both.