How is scleroderma classified?
Scleroderma can be classified in terms of the degree and location of the skin and organ involvement. Accordingly, scleroderma has been categorized into two major groups, localized scleroderma and systemic sclerosis. Systemic sclerosis is further subdivided into either diffuse or limited forms based on the location and extent of skin involvement.
Localized scleroderma skin changes are in isolated areas, either as morphea patches or linear scleroderma. Morphea is scleroderma that is localized to a patchy area of the skin that becomes hardened and slightly pigmented. Sometimes morphea can cause multiple lesions in the skin. Morphea is not associated with disease elsewhere within the body, only in the involved skin areas. Linear scleroderma is scleroderma that is localized usually to a lower extremity, frequently presenting as a strip of hardening skin down the leg of a child. Linear scleroderma in children can stunt bone growth of the affected limb. Sometimes linear scleroderma is associated with a "satellite" area of a patch of localized scleroderma skin, such as on the abdomen.
The widespread type of scleroderma involves internal organs in addition to the skin. This type, called systemic sclerosis, is subcategorized by the extent of skin involvement as either diffuse or limited. The diffuse form of scleroderma (diffuse systemic sclerosis) involves symmetric thickening of skin of the extremities, face, and trunk (chest, back, abdomen, or flanks) that can rapidly progress to hardening after an early inflammatory phase. Organ disease can occur early on and be serious and significantly decrease life expectancy. Organs affected include the esophagus, bowels, and scarring (fibrosis) of the lungs, heart, and kidneys. High blood pressure can be troublesome and can lead to kidney failure (renal crisis).
The limited form of scleroderma tends to have far less skin involvement with skin thickening confined to the skin of the fingers, hands, and face. The skin changes and other features of disease tend to occur more slowly than in the diffuse form. Because characteristic clinical features can occur in patients with the limited form of scleroderma, this form has taken another name that is composed of the first initials of the common components. Thus, this form is also called the "CREST" variant of scleroderma. CREST syndrome represents the following features:
C...Calcinosis refers to the formation of tiny deposits of calcium in the skin. This is seen as hard whitish areas in the superficial skin, commonly overlying the elbows, knees, or fingers. These firm deposits can be tender, can become infected, and can fall off spontaneously or require surgical removal. This is the least common of the CREST scleroderma variant features.
R...Raynaud's phenomenon refers to the spasm of the tiny arterial vessels supplying blood to the fingers, toes, nose, tongue, or ears. These areas turn white, then blue, then red after exposure to extremes of cold, or even sometimes with extremes of heat or emotional upset. This can lead to tiny areas of damage to the tips of the fingers (digital ulcers) or larger areas of dead skin on the ends of the fingers.
E...Esophagus disease in scleroderma is characterized by poorly functioning muscle of the lower two-thirds of the esophagus (the swallowing tube through which food passes from the mouth to the stomach). This can lead to an abnormally wide esophagus that allows stomach acid to backflow into the esophagus to cause heartburn, inflammation, and potentially scarring that narrows the esophagus. This can eventually lead to difficulty in passing food from the mouth through the esophagus into the stomach. Symptoms of heartburn are treated aggressively in patients with scleroderma in order to prevent injury to the esophagus.
S...Sclerodactyly is the localized thickening and tightness of the skin of the fingers or toes. This can give them a "shiny" and slightly puffy appearance. The tightness can cause severe limitation of motion of the fingers and toes. These skin changes generally progress much slower than those of patients with the diffuse form of scleroderma.
T...Telangiectasias are tiny red areas, frequently on the face, hands, and in the mouth behind the lips. These areas blanch when they are pressed upon and represent widened (dilated) capillaries.
Patients with limited systemic sclerosis can have variations of CREST with differing manifestations, for example, CRST, REST, or ST. Occasionally, patients can have initial illness with features of CREST that evolve into the diffuse form of scleroderma. Some patients have "overlaps" of scleroderma and other connective tissue diseases, such as rheumatoid arthritis, systemic lupus erythematosus, and polymyositis. When features of scleroderma are present along with features of polymyositis, systemic lupus erythematosus, and certain abnormal blood tests, the condition is referred to as mixed connective tissue disease (MCTD).