A 40-year-old man presents with chronic diarrhea, weight loss, and a rash on his elbows. He also complains of intermittent abdominal pain. What are the potential diagnoses and next steps?
This patient's symptoms, especially the combination of gastrointestinal symptoms and the rash, could suggest Celiac disease, an autoimmune disorder triggered by ingestion of gluten. The next steps would include serologic tests for antibodies typically found in Celiac disease (anti-tissue transglutaminase and anti-endomysial antibodies). If positive, an upper endoscopy with small bowel biopsy would confirm the diagnosis.