Differential Diagnosis for Undifferentiated Connective Tissue Disease

The patient's presentation and bloodwork suggesting lupus warrant a comprehensive differential diagnosis. The following categories outline potential diagnoses:

• Single Most Likely Diagnosis

  • Undifferentiated Connective Tissue Disease (UCTD): This is the most likely diagnosis given the patient's symptoms and bloodwork that points toward lupus but does not fully meet the criteria for a specific connective tissue disease like Systemic Lupus Erythematosus (SLE).

• Other Likely Diagnoses

  • Systemic Lupus Erythematosus (SLE): Although the patient's symptoms may not fully meet the criteria for SLE, it remains a likely diagnosis due to the bloodwork indicating lupus-like features.
  • Mixed Connective Tissue Disease (MCTD): This disease combines features of lupus, scleroderma, and polymyositis, and could be considered if the patient's symptoms overlap between these conditions.
  • Rheumatoid Arthritis (RA): While primarily an autoimmune disease affecting the joints, some patients with RA can have systemic symptoms that might mimic those of lupus or UCTD.

• Do Not Miss Diagnoses

  • Antiphospholipid Syndrome (APS): This condition can present with symptoms similar to lupus and is known for its association with thrombosis and pregnancy complications. Missing APS could lead to severe outcomes.
  • Sjögren's Syndrome: An autoimmune disorder that primarily affects the glands, especially the salivary and tear glands, but can also have systemic manifestations similar to lupus.
  • Vasculitis: Conditions like granulomatosis with polyangiitis (formerly known as Wegener's granulomatosis) can present with systemic symptoms and require early diagnosis to prevent organ damage.

• Rare Diagnoses

  • Scleroderma (Systemic Sclerosis): Characterized by skin thickening and potential involvement of internal organs, scleroderma can have a varied presentation that might initially resemble UCTD or lupus.
  • Polymyositis/Dermatomyositis: Inflammatory muscle diseases that can have overlapping features with connective tissue diseases, including skin manifestations and systemic symptoms.
  • Relapsing Polychondritis: A rare disease involving cartilage inflammation that can mimic some features of connective tissue diseases, including lupus.