Sentence:  <WSD>Fistulas</WSD> are abnormal communications between two epithelialized surfaces. The causes of enterocutaneous <WSD>fistulas</WSD> can be remembered using the mnemonic FRIEND: <WSD>F</WSD>oreign body, Radiation, <WSD>I</WSD>nflammation/Infection/Inflammatory bowel disease, Epithelialization, Neoplasm, and Distal obstruction. Fifteen to twenty-five percent of enterocutaneous <WSD>fistulas</WSD> arise spontaneously as in, for example, Crohn's disease or cancer. 
Meaning of the word marked with <WSD> tags:  An abnormal connection or passageway between organs or vessels that normally do not connect.