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Article Excerpt
Systemic sclerosis (SSc), or scleroderma, is a condition of connective tissue characterized by inflammation and fibrosis of the skin and internal organs. The disease is rare but associated with significant morbidity and mortality.
Early and proper diagnosis of SSc provides the opportunity for meaningful intervention, but several conditions that present with skin hardening may delay and confuse the diagnosis. The more common scleroderma mimics include localized scleroderma (LS), or morphea; nephrogenic fibrosing dermopathy (NFD); eosinophilic fasciitis (EF); chronic graft versus host disease (GVHD); diabetic cheiroarthropathy; and scleredema adultorum. Recognizing a few fundamental facts about SSc helps avoid misdiagnosis. In this article, we discuss the important clinical features of SSc and how this information may help distinguish it from the conditions that have skin induration as a major clinical feature.
EPIDEMIOLOGY
As a group, scleroderma mimics occur as frequently as SSc, if not more frequently. SSc occurs mostly in adults and rarely in children; the incidence is about 19.3 adult cases per million persons per year, and the prevalence is about 276 adult cases per million persons. (1) Peak incidence occurs in the fifth and sixth decades of life. There is a predominance in women (female to male ratio, 3-8:1).
Although SSc is seen in all racial groups, disease expression differs in various ethnic groups. SSc can be divided into 2 major clinical variants: diffuse and limited (Table 1). Patients of African ancestry are 1.86 times more likely than white patients to have diffuse disease. (1)
CLINICAL FEATURES
The difference between the diffuse and limited variants of SSc lies in the extent of skin involvement. Diffuse cutaneous SSc involves the extremities (proximal and distal) and the trunk; limited SSc involves the extremities distal to the elbows and knees, with truncal sparing. Both variants affect the face and neck. Patients with CREST (calcinosis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly, telangiectasia) syndrome fall within the limited variant of SSc. (2) Sine scleroderma and the overlap syndrome are less common variants of SSc.
Principal features
The most salient features of SSc are skin thickening and the presence of Raynaud phenomenon. Skin change occurs in 3 sequential stages: edematous (characterized by tight, puffy fingers), indurative (characterized by tight, thickened skin that adheres to the underlying subcutis), and atrophic (characterized by softening of the thickened skin; occurs after several years). (3) Skin involvement may occur rapidly in the first few months of disease, moving proximally, and may continue for 1 to 3 years, after which it enters the atrophic phase.
Raynaud phenomenon is the result of vasospasm of digital arteries, arterioles, and arteriovenous shunts of the skin; the condition is incited by cold temperatures and emotional stress. Blanching of the digits is followed by cyanosis and, finally, hyperemia. Raynaud phenomenon occurs in 90% to 98% of patients with SSc and may predate the development of skin involvement by several years. (4) Severe disease is associated with digital tip reabsorption and ulcerations.
Organ involvement
GI tract involvement is common in SSc, affecting 75% to 90% of patients. (5) Smooth muscle atrophy and submucosal fibrosis result in dysmotility of the entire GI tract. Esophageal dysfunction results in dysphagia and dyspepsia; gastric involvement produces delayed emptying, with nausea, bloating, and early satiety. Small-intestine dysmotility results in abdominal pain, diarrhea, and pain caused by malabsorption due to bacterial overgrowth and pseudo-obstruction. Colonic involvement may manifest as constipation and megacolon.
Pulmonary abnormalities, particularly restrictive lung disease, are common manifestations in diffuse SSc, occurring in 90% of patients. 6 Moderate to severe interstitial lung disease develops in about 40% of patients. (6) The most common symptoms are shortness of breath and, later, a nonproductive cough. Pulmonary artery hypertension (PAH) is more common in patients with limited SSc; it usually presents about 10 years after the original diagnosis. PAH also occurs in up to 10% to...
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