Differential Diagnosis

The patient's presentation with a positive ANA, scl-70 positivity, and specific clinical symptoms such as atypical Raynaud's and autonomic dysfunction suggests an autoimmune connective tissue disease. Here's a categorized differential diagnosis:

• Single most likely diagnosis

  • Undifferentiated Connective Tissue Disease (UCTD): This diagnosis is considered because the patient has a positive ANA with a high titer, presence of specific autoantibodies (scl-70, anti-Mi-2), and clinical features (atypical Raynaud's, autonomic dysfunction, intermittent leukopenia) that do not fully meet the criteria for a specific connective tissue disease like systemic sclerosis or systemic lupus erythematosus.

• Other Likely diagnoses

  • Systemic Sclerosis (Scleroderma): The presence of scl-70 antibodies, which are commonly associated with systemic sclerosis, especially the diffuse form, makes this a consideration. However, the lack of skin thickening or other organ involvement typical of scleroderma keeps it from being the top diagnosis.
  • Systemic Lupus Erythematosus (SLE): Although the patient has a high-titer ANA and some suggestive symptoms like leukopenia, the absence of more definitive SLE criteria (e.g., malar rash, oral ulcers, nephritis) makes this less likely.
  • Mixed Connective Tissue Disease (MCTD): This condition overlaps with features of lupus, scleroderma, and polymyositis/dermatomyositis. The presence of anti-Mi-2 (more commonly associated with dermatomyositis) and scl-70 antibodies, along with clinical features, could suggest MCTD, but the specific combination of antibodies and symptoms does not fully align with classic MCTD.

• Do Not Miss

  • Sjögren's Syndrome: Although primarily known for causing dry eyes and mouth, Sjögren's can have systemic manifestations and is often associated with a positive ANA. It's crucial to consider due to its potential for significant morbidity if untreated.
  • Rheumatoid Arthritis (RA): While the clinical presentation does not strongly suggest RA, the presence of autoantibodies and potential for overlap syndromes means RA should be considered, especially if joint symptoms develop.

• Rare diagnoses

  • Eosinophilia-Myalgia Syndrome: This rare condition, associated with certain autoantibodies and characterized by eosinophilia and myalgias, is a consideration in patients with unexplained autoimmune symptoms, though it's less likely given the specific antibodies and symptoms presented.
  • Autoimmune Myopathies (e.g., Dermatomyositis, Polymyositis): The presence of anti-Mi-2 antibodies suggests dermatomyositis, but the clinical presentation lacks the characteristic skin and muscle findings, making this a less likely but not impossible diagnosis.