This 25 year old woman presents with chronic diarrhea, iron deficiency and a pruritic rash (pictured) on her knees and elbows. What is the most likely diagnosis?

This woman most likely has celiac disease and dermatitis herpetiformis (which is seen in 15-25% of patients with CD). Celiac disease is a gluten-sensitive enteropathy involving IgA antibodies against the skin and gut.  It is also associated with iron deficiency, malnutrition, chronic diarrhea.  Patients may also have a personal or family history of auto-immune thyroid disease, type 1 diabetes, pernicious anemia, vitiligo or other auto immune conditions.

The treatment is complete elimination of gluten from the diet to prevent long term complications including micronutrient deficiency (B12 & iron) as well as an increased risk of intestinal lymphoma and cardiovascular disease.  Additionally, Dapsone can be used to help alleviate skin symptoms that are not improved with diet alone.