Localized scleroderma – plaque type L 94.0

Chronic, sclerosing connective tissue disease of the skin that progresses in episodes, has a protracted but self-limited course and heals with atrophy of the skin. The involvement of internal organs such as the heart, lungs, kidneys or gastrointestinal tract is an absolute rarity in circumscribed scleroderma; transitions to systemic scleroderma are not detectable.

• Classic form: plaque or morphea type also limited form of ZS (about 60% of the total ZS collective)
• Generalized form of circumscribed scleroderma (maximum variant of the plaque or morphea type)
• Bullous, circumscribed scleroderma (bullous variant of the plaque type)
• Atrophizing type (atrophodermia idiopathica et progressiva) (about 20% of the total ZS collective)

w:m= 4:1; this ratio applies to both adults and children. The incidence in the overall population is 2/100,000, with similar incidences in children and adolescents. The disease occurs predominantly in whites (85%), 5% in blacks and 3% in Asians.

Insights into the pathogenesis of morphea are often extrapolated from studies of systemic sclerosis, as the histopathologic features of the skin are similar. Clinically, however, they are two distinct diseases that differ in demographics, clinical features, disease course and prognosis. With regard to their pathogenesis, genetic (correlation with HLA-B8, DR1, DR5), immunological, autoimmunological, hormonal, viral, bacterial, toxic, traumatic, drug-related, neurogenic or vascular factors are discussed. Cutaneous mosaic patterns can also be detected in the morphea type of circumscribed scleroderma.

It is expected that the candidate gene for inheritance susceptibility has single nucleotide polymorphisms (SNPs). The dominant region associated with localized scleroderma is a major histocompatibility complex. HLA class I and class II alleles are associated with the development of localized scleroderma, although in familial cases there is no common HLA haplotype in affected individuals in different families. Within families, patients with morphea share at least one HLA haplotype, while other family members with identical HLA haplotypes did not develop the disease. The role of the genetic factor was supported by cytogenetic evidence of chromosomal breaks as a result of an abnormal DNA repair process.

Radiation-induced morphea is interpreted as a rare complication of radiotherapy (radiation recall) (Spalek M et al. 2015).

Especially in young patients, Borrelia infections can initiate a circumscribed scleroderma (Borrelia associated early-onset morphea) or progress under the picture of a circumscribed scleroderma (Borrelia-specific antigens such as OspA or OspC have a high antigenic potential and can trigger autoreactive processes). See Borrelia below.

There is a growing consensus that an autoimmunological component is pathogenetically relevant (autoimmunological and rheumatic diseases in the family, concomitant rheumatic or autoimmunological diseases, ANA +).

Classic plaque or morphea type: Mostly painless, chronically stationary or progressive, localized on the trunk and extremities, varying in size (0.5-30.0 cm or larger), roundish or oval, also confluent over a large area, centrifugally expanding, sharply defined, white, red or brown flat indurations. In the center of the indurations, a white or yellow, hard plate is often formed, which is caked to the base and in which the follicular structure is missing (destruction of the hair follicles). These plate-like indurations are often surrounded by a ring-shaped, blue-violet to lilac-colored erythema border = lilac ring (sign of progression). The lesions of circumscribed scleroderma can be roundish to oval, also structured like a map. Cutaneous mosaic formations (e.g. checkerboard pattern), which indicate postsomatic mutations in as yet unknown genes, have also been detected.

Atrophodermia idiopathica et progressiva is a primarily atrophic variant of the plaque type with large, barely indurated, red-brown or red, slightly sunken atrophic areas.

The guttate form (also known as the confetti type) of circumscribed scleroderma usually shows disseminated, trunk-emphasized yellowish-whitish, superficially shiny, slightly indurated patches, papules or plaques barely 1 cm in size. Initially, pale red spots may appear.

According to the AWF guideline, the "generalized form of circumscribed scleroderma" is present if at least three anatomical localizations are affected. The trunk, thighs and the lumbosacral region are preferentially affected. The plaques often occur symmetrically and can confluent to form larger areas, in which case they are associated with movement disorders. The very rare "disabling pansclerotic morphea", which is classified as the maximum variant of generalized CS, is extremely severe (see illustration). The combination of linear and disseminated large areas with only a slight tendency to regression of the fibrosis often leads to contractures and wound healing disorders even in childhood.

In a review of adults (see also scleroderma, circumscribed juvenile), extracutaneous manifestations were observed in about 20% of cases, whereby these (apart from skeletal and muscular changes in the linear forms) play no clinical role:

Antinuclear antibodies: The data are (fluctuating depending on literature and type). 30-70% of patients are positive for antinuclear antibodies (ANA), the anti-topoisomerase II-alpha antibody (76%) is also detectable, as is the anti-single-stranded DNA antibody (with a wide distribution between 4% and 60% depending on the test). This could be an indication of systemic inflammatory activity. Important for the plaque type: the antibodies do not correlate with clinical activity and severity.

Inflammatory stage: Dense inflammatory infiltrate, mainly of lymphocytes. Edematous swelling of the collagen fiber bundles. Septal panniculitis in the upper parts of the fatty tissue with sparse or also nodular round cell infiltrates, also eosinophils and plasma cells at the dermo-subcutaneous border. Rare formation of germinal centers. Enclosure of fatty tissue lobules by collagenous bundles.

Sclerotic stage: widespread proliferation of dermal connective tissue at the expense of subcutaneous adipose tissue. Homogenized, widened collagen fibre bundles run parallel to the skin surface. Atrophic adnexa, slit-shaped constricted vessels. Walled-in eccrine sweat glands. Rather sparse perivascular and diffuse lymphocytic infiltrates. Nodular compaction of the infiltrates at the border to the subcutis. Broad, homogenized and also edematized fatty tissue septa with sparse round cell infiltrates.

Although circumscribed scleroderma usually has no internal organ manifestations such as interstitial lung disease or cardiac arrhythmias, the underlying and associated tissues are frequently affected in this clientele, leading to morbidity.

The frequency of extracutaneous involvement in circumscribed scleroderma varies in the literature between 20 and 70 %, depending on whether the data were collected retrospectively or prospectively, with prospective assessment data capturing more manifestations.

The most common extracutaneous manifestations across all cohorts are musculoskeletal manifestations, including arthralgias, arthritis, joint contractures, myositis and fasciitis, associated with disease-related gait disturbances, functional impairment, muscle, bone and limb atrophy.

Association with other autoimmunological and rheumatological diseases, in particular psoriasis vulgaris, systemic lupus erythematosus, multiple sclerosis and vitiligo.

Associations with genital lichen sclerosus have been described.

Generally active course over several years, after which the disease burns out, leaving the resulting sclerosis or atrophy.

25% of patients suffer a recurrence, which can occur even after years of latency. The linear form has a particularly high recurrence rate.

Indications of increased disease activity and a higher relapse rate are an early occurrence of circumscribed scleroderma and ANA positivity.