Elbow nodules

Differential includes morphea and scleromyxedema

A thorough history, physical exam, lab work, and possibly biopsy will help differentiate systemic scleroderma from the possible diagnoses with sclerosis listed below:

• Morphea features a localized, patchy distribution of skin fibrosis. There is no systemic involvement or Raynaud’s phenomenon.
• Mixed connective tissue disease has features of other autoimmune diseases, along with those of scleroderma.
• Eosinophilic fasciitis involves the fascia and muscle on biopsy. There is sparing of the hands.
• Scleromyxedema represents the skin thickening seen in patients with a gammopathy. Raynaud’s phenomenon may also be present.
• Scleredema is associated with diabetes. Skin changes are found mostly on the neck, shoulders, and upper arms. On rare occasions, there is visceral involvement. Raynaud’s phenomenon is not present.

In addition, the differential includes chronic graft-vs-host disease; lichen sclerosis et atrophicus; amyloidosis; porphyria cutanea et tardia; primary Raynaud’s phenomenon; and polyvinyl chloride, bleomycin, or pentazocyine exposure.

Nailfold capillary abnormalities help with the diagnosis

As noted earlier, diagnosing systemic scleroderma hinges on taking a good history, doing a thorough physical exam, applying the ACR diagnostic criteria, and ordering lab work. The sensitivity of the ACR criteria increases from 67% to 99% with the addition of nailfold capillary abnormalities (telangiectasias), identified using a dermatoscope.⁵

The initial lab work that you should consider includes an antinuclear antibody (ANA) test, complete blood count, and erythrocyte sedimentation rate. If the ANA is positive, anticentromere antibody (ACA) and DNA topoisomerase I (Scl-70) antibody tests should be ordered to see if scleroderma is likely limited or diffuse. ACA will be present in 21% of dSSc and 71% of lSSc cases, whereas Scl-70 will be present in 33% of dSSc and 18% of lSSc cases.⁶