Abstract

Introduction

Mixed connective tissue disease (MCTD) is a subset of rheumatic overlap syndromes, characterized by anti-U1RNP antibodies and features of multiple inflammatory connective tissue diseases, including systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). 

Case Presentation

A 23-year-old female presented with abdominal pain, fatigue, subjective fevers, and generalized joint pain that was acutely worsening over the past 3 weeks. She had a recent medical history of new-onset colitis and urinary tract infection (UTI) not resolved with multiple courses of antibiotics. The patient was admitted for acute pyelonephritis and acute kidney injury due to a complicated UTI. However, her presenting symptoms in conjunction with the additional findings of normocytic anemia, bilateral pleural effusion, elevated inflammatory markers, and family history of RA also prompted further autoimmune evaluation. During her hospital course, the patient developed an oral ulcer and bilateral edema in the hands. The finding of U1RNP antibodies supported the diagnosis for MCTD. The patient’s condition subsequently improved with antibiotics, NSAIDs, and steroids.  Following discharge, the patient was to follow up closely with her primary care provider, and specialists in gastroenterology and rheumatology.  

Discussion 

Uncertainty in a MCTD diagnosis is commonly due to the changing nature of the disease and variability in case presentation with mixed support of differentiated disease. With U1RNP antibodies and features supporting an RA/SLE overlap syndrome in our patient, a MCTD diagnosis was made. 

Conclusion

MCTD is a rare autoimmune disorder that predisposes patients to significant morbidity and mortality. It is imperative to recognize the clinical features of MCTD for adequate symptomatic treatment.