PSS leads to progressive dense connective tissue replacement in certain areas that normally contain only small amounts of loose collagen. These include the dermis of the skin, the submucosa of the esophagus or other parts of the GI tract, and the heart. The lungs frequently develop a slowly progressive type of diffuse fibrosis, radiologically most prominent in the lung bases. In addition, the kidneys are often affected by a somewhat different histologic process, similar to malignant hypertension. The disease is most common in middle-aged women. Clinically, the skin changes produce tautness and lack of elasticity; these changes most often occur in the hand and are often accompanied by Raynaud’s phenomenon. Esophageal involvement leads to dysphagia, and small bowel changes may produce localized dilation.

Laboratory aspects. Laboratory tests usually show normal hemoglobin levels. There may be an increased ESR, and there may be associated hypergammaglobulinemia of a diffuse type, although this is not a consistent feature. Progressive system sclerosis gives a positive ANA test result in about 70% of cases, and the anti-DNA test may be positive in about 15% of cases. Various autoantibodies have been reported in a minority of cases (including Scl-70 in 45% of patients). Antinucleolar antibodies in high titer are very suggestive of PSS. Rheumatoid factor test results are positive in about 15% of cases, and there may be a biologic false positive agglutination test result for syphilis.

Diagnosis usually can be made clinically but may be suggested by barium swallow esophageal x-ray studies in patients who have esophageal symptoms. Biopsy of an affected skin area is the procedure of choice if the diagnosis cannot be made clinically.