All are true about Ulcerative colitis except

.Disease commonly stas in the rectum, spreads proximally to the colon and often into the ileum as back wash ileitis (5%).* It is a disease confined to mucosa and submucosa. * There is no bowel wall thickening and no granuloma formation. * There are no skip lesions. Rectum is always involved. Distal bowel is involved to begin with, then spreads proximally. Distal involvement is more severe. Entire colon including caecum and appendix may be involved. ref:SRB&;s manual of surgery,ed 3,pg no 824