Classification scheme of scleroderma
It is crucial to distinguish the localized forms of scleroderma (: Scleroderma Mimics) from the generalized (systemic) forms.
• Localized scleroderma: dermal fibrosis without internal organ involvement. The two types of localized scleroderma are:
1. Morphea: single or multiple plaques, commonly on the trunk.
2. Linear scleroderma: bands of skin thickening commonly located on the legs or arms, but sometimes on the face ( en coup de sabre ) that typically follow a linear path.
• Generalized scleroderma = SSc.
1. Limited cutaneous SSc (lcSSc, limited scleroderma): Patients with lcSSc have skin thickening limited to the neck, face, or distal to the elbows and knees. Patients with lcSSc may not come to clinical attention until many years after symptom onset. They often describe longstanding Raynaud’s phenomenon and gastroesophageal reflux disease (GERD) and may have telangiectasia, skin calcifications (calcinosis), and digital edema or sclerodactyly as their only skin manifestations. Among those with lcSSc, the presence of anti-Scl-70 (anti-topoisomerase) antibody is associated with a high risk for the development of progressive ILD, and the presence of anticentromere antibody (ACA) carries the highest risk for PAH. Renal crisis is exceedingly rare in lcSSc. Limited scleroderma is not “mild” scleroderma, as the “limited” descriptor refers only to limited skin involvement and not internal organ manifestations. Patients with lcSSc still have life-threatening disease as driven by pulmonary, cardiac, or gastrointestinal (GI) involvement.
Diffuse scleroderma (dcSSc): Patients with dcSSc have skin thickening that extends proximal to the elbows or knees or with truncal involvement. In contrast to lcSSc, patients with dcSSc usually present relatively abruptly. Common presenting symptoms include puffy hands, Raynaud’s phenomenon, arthritis, carpal tunnel symptoms (due to surrounding edema or inflammation), fatigue, and rapidly progressive skin thickening. These patients often have the onset of Raynaud’s phenomenon within a year of developing SSc. Patients with dcSSc are at a higher risk for progressive ILD and can also develop PAH. Patients with diffuse skin thickening and a positive RNA polymerase III antibody are at highest risk of developing SRC.
3. Systemic sclerosis sine scleroderma (ssSSc): Patients with internal manifestations of SSc along with a scleroderma-specific antibody (such as a nucleolar-pattern antinuclear antibody [ANA], ACA, anti-Scl-70 antibody, or anti-RNA polymerase III antibody), but without evidence of skin thickening, are described as having ssSSc. Some experts consider this a subset of lcSSc, given that some patients early in the disease course may develop subsequent cutaneous involvement. Nonetheless, a distinct population will lack cutaneous features over time and fall within this category of SSc. Examples of ssSSc include:
• Raynaud’s phenomenon, digital edema, ILD, and a positive anti-Scl-70 antibody
• Raynaud’s phenomenon, GERD, PAH, and a positive ACA
• Raynaud’s phenomenon, renal crisis, and a positive anti-RNA polymerase III antibody.