The term “systemic sclerosis” indicates that sclerosis (hardening) may occur in the internal systems of the body. Affected body parts may include the skin, lungs, heart, kidney esophagus, gastrointestinal tract (stomach and bowels), and other internal organs. SSc can also affect blood vessels, muscles, and joints. Affected tissues become hard and fibrous, resulting in less efficient function.
The extent of skin involvement determines whether a patient has limited cutaneous SSc or diffuse cutaneous SSc. In lcSSc, skin thickening occurs on the hands, forearms, lower legs, and feet. In dcSSc, skin thickening occurs on the hands, forearms, upper arms, thighs, or trunk. Both forms can affect the skin on the face.
In addition to less widespread skin thickening, internal problems are less frequent and tend to be less severe than in dcSSc. Onset of internal problems is usually delayed for several years. However, the disease can still be extremely severe. Pulmonary hypertension can develop in patients with lcSSc (and occasionally those with diffuse). In pulmonary hypertension, impaired blood flow through the lungs due to the narrowing of the lung’s blood vessels causes shortness of breath.
The acronym “CREST” refers to the five common symptoms of lcSSc: Calcinosis, Raynaud’s Phenomenon, Esophageal dysfunction, Sclerodactyly, and Telangiectasia. (Learn what these words mean in the “Key Terms” page of the Learn Center!) Some patients with diffuse scleroderma will also develop calcinosis and telangiectasias.
Skin thickening typically occurs more rapidly and involves more skin areas in patients with dcSSc than in patients with the limited form. Patients with dcSSc have a higher risk of developing pulmonary fibrosis, also known as interstitial lung disease; in pulmonary fibrosis, scar tissue in the lungs interferes with breathing. Kidney involvement also occurs more frequently in dcSSc patients, especially in the first five years after diagnosis, and usually takes the form of a sudden blood pressure increase. If untreated, this high blood pressure can damage the kidney in a matter of weeks; thus, it is called a scleroderma renal crisis. The likelihood of extensive gut involvement (slowing of stomach/bowel movement or motility) is higher in those with the diffuse form. Patients may feel bloated after eating, have diarrhea, or have alternating diarrhea and constipation.
The scleroderma rarely spreads elsewhere, and internal organs are typically unaffected. Generally, localized scleroderma is relatively mild. Although localized scleroderma is not fatal, the condition may still adversely affect quality of life. Patients with localized scleroderma rarely develop the systemic form.
The four main types of localized scleroderma are morphea, generalized morphea, linear scleroderma, and en coup de sabre.
The skin under these waxy patches may thicken. In addition, the fatty layer underneath the morphea spots is usually lost. The patches, which tend to be lighter or darker than the surrounding skin and thus tend to stand out, can vary in size from half an inch to six inches or more in diameter. Morphea patches can enlarge, shrink or even disappear spontaneously. Although morphea usually appears between the ages of 20 and 50, it is often seen in young children.
Sometimes, a long crease on the head or neck forms; this crease is referred to as “en coup de sabre” because of the resemblance to a saber (sword) wound. Linear scleroderma typically involves the deeper skin layers as well as the surface layers. Sometimes, the motion of the joints that lie underneath the skin is also affected. The fatty layer under the skin can be lost, resulting in an affected limb that is thinner than the other one. In growing children, linear scleroderma may cause the limb to be shorter than the unaffected one. Linear scleroderma typically develops during childhood.
Systemic scleroderma (SSc), the type of scleroderma that also affects the internal organs, is the more common type of scleroderma in adults. However, in children, LS is around 10 times as common as SSc. Juvenile localized scleroderma (jLS) affects 50 per 100,000 children – a prevalence similar to that of juvenile diabetes mellitus. The estimated prevalence of juvenile systemic scleroderma (jSSc) is 2 per 100,000.
Localized and systemic scleroderma are distinct. It is extremely rare for both to occur together (<0.1%). When this does happen, they typically have a similar time of onset. One does not develop into the other.
LS subtypes include linear scleroderma (trunk/limb, head), circumscribed morphea (superficial or deep), mixed morphea, and generalized morphea. In children, mixed morphea and linear scleroderma of the trunk/limb and head are much more frequent.
This is due to the increased frequency of deeper tissue involvement in jLS linear subtypes. Such extracutaneous involvement includes joint contracture, limb length differences (affected limb is shorter), and limb girth differences (affected limb has a smaller girth). If linear head involvement is present, skull changes, linear band on the scalp, mandible/maxilla (jaw) changes, brain lesions/changes, or neurological symptoms may occur.
Cohort studies on adults generated the thought that LS would “burn out” after 3-5 years. However, more recent cohort studies have shown that this does not apply to jLS. In jLS, disease duration can range from 7 to 10+ years. For example, a recent European cohort demonstrated that 12.5% of jLS patients still had active diseases after 10 years. (Marini, Zulian Autoimmunity Reviews 17 (2018) 727-734) With a longer disease duration in jLS, there is a higher risk for sequela of (lasting damage to) the underlying tissue if it is left untreated.
Compared to adult-onset, the rate of internal organ involvement is typically less. Thus, the prognosis is more favorable. This trend in severity is opposite of the differences observed in localized scleroderma. However, systemic scleroderma affects each child differently and can be extremely severe. Juvenile systemic sclerosis differs from the adult-onset disease. The diffuse subtype dominates, and the disease often presents insidiously.
It has been suggested that older systemic scleroderma patients are at a greater risk for pulmonary hypertension, renal impairment, cardiac disease, and muscle weakness. It has also been suggested that late-age onset is protective against digital ischemia (reduced blood flow), with lower prevalences/severities of Raynaud’s Phenomenon and digital ulcers. These differences and the reasons for them have not been thoroughly studied or confirmed.
However, awareness of the distinct risk for specific organ involvement in SSc, especially pulmonary hypertension, should guide the care of elderly SSc patients.