▁by ▁short - chain ▁fat ty ▁ac ids , ▁which ▁are ▁produced ▁as ▁a ▁result ▁of ▁b acter ial ▁fer ment ation ▁in ▁the ▁gut . ▁Long - term ▁lack ▁of ▁expos ure ▁to ▁these ▁nut ri ents ▁can ▁cause ▁infl amm ation ▁of ▁the ▁colon ▁( col itis ). ▁Sym pt oms ▁include ▁rect al ▁ble eding , ▁m uc ous ▁dis charge , ▁ten es mus , ▁and ▁ab dom inal ▁pain . ▁ ▁Vol v ulus ▁ ▁Col onic ▁ul cers ▁ ▁Function al ▁ ▁M uc os al ▁pro lapse ▁synd rom es ▁ ▁Sol it ary ▁rect al ▁ul cer ▁synd rome ▁▁▁ ▁In ternal ▁int uss us ception ▁ ▁M uc os al ▁pro lapse ▁ ▁Rect al ▁pro lapse ▁ ▁Ir rit able ▁bow el ▁synd rome ▁ ▁P neum atos is ▁c yst o ides ▁int est inal is ▁ ▁Pr ur it us ▁ani ▁ ▁M align ancy ▁ ▁Anal ▁car cin oma ▁ ▁Anal ▁car cin oma ▁is ▁much ▁less ▁common ▁than ▁col ore ct al ▁cancer . ▁The ▁most ▁common ▁form ▁is ▁squ am ous ▁cell ▁car cin oma , ▁followed ▁by ▁ad en oc arc in oma ▁and ▁mel an oma . ▁S CC ▁usually ▁occurs ▁in ▁the ▁anal ▁canal , ▁and ▁more ▁rarely ▁on ▁the ▁anal ▁margin . ▁Anal ▁margin ▁S CC ▁presents ▁as ▁a ▁les ion ▁with ▁rolled , ▁e vert ed ▁edges ▁and ▁central ▁ul cer ation . ▁Sym pt oms ▁include ▁a ▁pain ful ▁l ump ,