The Clinical Picture

Thick skin on the back

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Figure 1. Erythematous induration of the skin limited to the back.

A 66-year-old obese black woman with long-standing uncontrolled type 2 diabetes mellitus (hemoglobin A1c 15.1%) presents with an indurated, wood-like thickening of the skin on her back, with mild pitting (Figure 1). This condition has been present for 3 years and is associated with diffuse erythema. She denies any history of Raynaud phenomenon, arthralgias, dysphagia, or rashes. Her antinuclear antibody titer is highly positive at 1:640 dilution, with a speckled pattern. All other autoantibody tests (antitopoisomerase-I, Sjögren antibodies, anti-Smith and anti-Smith/ribonucleoprotein, and antiphospholipid nucleoprotein, and antiphospholipid antibodies) are negative. Serum electrophoresis and urinary porphobilinogen levels are normal.

Q: Which is the correct diagnosis?

  • Scleroderma (systemic sclerosis)
  • Scleredema diabeticorum
  • Amyloidosis
  • Cutaneous sarcoidosis
  • Porphyria cutanea tarda

A: The correct answer is scleredema diabeticorum, a common, underdiagnosed skin manifestation of uncontrolled diabetes mellitus seen in 2.5% to 14% of diabetic patients.1,2 It most often presents with the insidious onset of painless induration and nonpitting thickening of the skin, predominantly on the upper back and neck. Biopsy of the skin usually reveals thickening of the dermis with deposition of collagen and hyaluronic acid without an inflammatory infiltrate.3

Of note, patients may present with similar skin changes acutely in conditions such as postinfectious scleredema (scleredema of Buschke) and paraproteinemias.

Treatment of scleredema is usually difficult, but options include radiotherapy, ultraviolet light therapy, low-dose methotrexate, psoralen, and extracorporeal photopheresis.4–7

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