Co-Occurrence of Systemic Sclerosis, Lupus, and Celiac Disease in Multiple Autoimmune Syndrome: A Case Report

BACKGROUND Multiple autoimmune syndromes are caused by immune dysregulation pathways and shared genetic polymorphisms, resulting in the coexistence of multiple autoimmune disorders. Systemic sclerosis (SSc) and systemic lupus erythematosus (SLE) are connective tissue diseases with distinct pathogenesis. Celiac disease (CD) is an immune-mediated small intestine pathology. Previous case reports have documented the coexistence of SLE and CD, SSc and CD, and SSc and SLE (overlap syndrome). CASE REPORT A 21-year-old woman with juvenile SSc and interstitial lung disease was admitted with fever, cough, and ongoing lower abdominal pain, diarrhea, and weight loss for the previous 3 months. Laboratory investigations revealed leukopenia, normocytic normochromic anemia, and thrombocytopenia, with positive antinuclear antibody and anti-double-stranded DNA. SLE was diagnosed, and the patient was started on a steroid and hydroxychloroquine. Celiac serology was ordered, followed by an upper gastrointestinal endoscopy, with biopsy. The results of both tests indicated CD. The patient was advised to follow a gluten-free diet and was started on hydroxychloroquine, mycophenolate mofetil, and prednisolone. CONCLUSIONS Our patient's presentation of CD and SLE occurring 9 years after SSc onset is unique. Individuals with one autoimmune disease have approximately a 25% chance of developing another. Limited case reports discuss CD in patients with SSc and the association between CD and SLE. To the best of our knowledge, no prior reports documented the coexistence of SSc, SLE, and CD. This case report underscores the importance of investigating autoimmune syndromes based on clinical presentation, as rare associations can occur.