A right lower quadrant mass in cystic fibrosis: a diagnostic challenge.

In a cystic fibrosis (CF) patient a right lower quadrant (RLQ) mass may be a difficult diagnostic problem. Most frequently it is due to a distal intestinal obstruction syndrome also called meconium ileus equivalent, but the possibility of intussusception and appendiceal abscess should also be considered. We describe three CF patients with an appendiceal abscess seen in a 4-year period. All three patients had a palpable RLQ mass. Chronicity and obliteration of the appendiceal lumen with abnormally viscid mucus may lead to concealed perforation and be responsible for the atypical presentation.