Differential Diagnosis for a 40-year-old Patient with Arthralgia and Specific Laboratory Results

The patient presents with arthralgia, a positive nucleolar antinuclear antibody (NA) pattern with a titer of 1:1280, and a positive centromere antibody. These findings are crucial for narrowing down the differential diagnosis.

• Single Most Likely Diagnosis

  • Limited Systemic Sclerosis (lSSc): This condition, also known as limited systemic scleroderma, is characterized by skin thickening limited to the hands, arms, and face, along with the presence of centromere antibodies in the majority of cases. The nucleolar pattern of antinuclear antibodies (ANA) can also be seen in systemic sclerosis. The high titer of ANA (1:1280) supports an autoimmune process, which is consistent with lSSc.

• Other Likely Diagnoses

  • Diffuse Systemic Sclerosis (dSSc): Although less likely than lSSc given the presence of centromere antibodies, dSSc is a consideration, especially if there are signs of widespread skin thickening and internal organ involvement. The nucleolar ANA pattern can be seen in both limited and diffuse forms.
  • Mixed Connective Tissue Disease (MCTD): This disease overlaps with systemic lupus erythematosus (SLE), systemic sclerosis, and rheumatoid arthritis. While MCTD typically presents with a high titer of anti-U1 RNP antibodies, the presence of a high-titer ANA and arthralgia could suggest this diagnosis, although centromere antibodies are less common in MCTD.

• Do Not Miss Diagnoses

  • Systemic Lupus Erythematosus (SLE): Although SLE typically presents with a variety of autoantibodies and a more diverse clinical picture, it is crucial not to miss this diagnosis due to its potential for serious organ involvement. The high-titer ANA is consistent with SLE, but the specific pattern and presence of centromere antibodies are less typical.
  • Rheumatoid Arthritis (RA): While RA is primarily associated with anti-CCP and rheumatoid factor, a small subset of patients may have a positive ANA. Given the potential for severe joint damage and the fact that arthralgia is a presenting symptom, RA should be considered, especially if there are signs of inflammatory arthritis.

• Rare Diagnoses

  • Overlap Syndromes: These are conditions that combine features of different autoimmune diseases, such as scleroderma-polymyositis overlap. The presence of centromere antibodies and a nucleolar ANA pattern, along with arthralgia, might suggest a rare overlap syndrome.
  • Undifferentiated Connective Tissue Disease (UCTD): This diagnosis is considered when patients have symptoms and autoantibodies suggestive of a connective tissue disease but do not meet the full criteria for a specific disease like SLE, systemic sclerosis, or RA. The patient's presentation could fit UCTD, especially if the clinical picture evolves over time.