Collagenous sprue is a disease associated with and often at first mistaken for celiac sprue. It is a more rare condition and a gluten-free diet does not always do the trick the way it does with celiac disease.
Check out this video from News channel 9 where Dr. John Torres calls collagenous sprue a "very difficult condition" and suggests that multiple regimes be tested to determine the best treatment for each individual person.
The personal story comes from a daughter whose mother was diagnosed with celiac disease and started a gluten-free diet but did not see great results. She was eventually diagnosed with collagenous sprue as well.
Check out the video to learn the differences in conditions and how they could potentially be linked and treated.