Table 1.
Overview of C4.4A and Haldisin Expression in Non-invasive Skin Lesions.
| Type | Lesion | No. of cases | Lesion Description | C4.4A | Haldisin |
|---|---|---|---|---|---|
| Blistering disorders | Bullous pemphigoid | 4 | Detachment of basal layer from the basement membrane due to IgG autoantibodies targeting type XVII collagen of hemidesmosomes | 4/4: No alteration | 4/4: No alteration |
| Epidermolysis bullosa dystrophica | 2 | Detachment of basal layer from the basement membrane due to mutations in collagen VII | 2/2: No alteration | 2/2: No alteration | |
| Pemphigus vulgaris | 2 | Acantholysis and detachment of keratinocytes primarily in the basal and lower spinous layer due to IgG autoantibodies against desmoglein 3 | 2/2: No alteration | 2/2: No alteration | |
| Pemphigus foliaceus | 7 | Acantholysis and detachment of keratinocytes primarily in the granular layer due to IgG autoantibodies against desmoglein 1 | 7/7: No alteration | 6/7: Loss of expression due to loss of granular layer | |
| Subcorneal pustular dermatosis | 3 | Cytolysis of keratinocytes of the granular layer and formation of subcorneal pustules | 3/3: No alteration | 1/3: Loss of expression under pustule | |
| Darier disease | 5 | Acantholysis of suprabasal keratinocytes and dyskeratinization due to a mutation in the Ca2+ ATPase SERCA2 causing breakdown of desmosome-keratin intermediate filaments and desmosome loss. | 1/5: Membrane associated expression in basal cells 4/5) No alteration |
2/5: Thickening of Haldisin expressing cell layer 5/5) Loss of expression with acantholysis |
|
| Lesions harboring dysregulated differentiation | Ichthyosis | 4 | Heterogeneous group of scaling disorders caused by known gene mutations Examined types 1 ichthyosis congenital. 1 nonbullous congenital ichthyosiform erythroderma (NBCiE) 1 autosomal dominant lamellar ichthyosis1 ichthyosis congenital type IV |
4/4: No alteration | 1/4: Thickening of Haldisin expressing cell layer in the case of NBCiE |
| Lichen ruber planus | 7 | Inflammatory disorder where an unknown antigen leads to lymphocyte activation and subsequent keratinocyte apoptosis, basal membrane disruption, subepidermal cleft formation and thickening of the granular layer. | 7/7: No alteration | 5/7: Thickening of Haldisin expressing cell layer which largely recapitulates the expression of profilaggrin/loricrin | |
| Psoriasis | 4 | Inflammatory disease with excessive hyperproliferation of keratinocytes both in the basal- and suprabasal layer. Loss of the granular layer and formation of para- and hyperkeratosis. | 4/4: No alteration | 3/4: Thick Haldisin expressing cell layer despite loss of profilaggrin/ loricrin expression |
Sections of blistering lesions as well as lesions harboring a dysregulated differentiation were stained for C4.4A and Haldisin. The table lists the lesion types, the number of cases examined, a short description of the main characteristics of the diseases and, finally, an evaluation of the C4.4A and Haldisin expression patterns. The numbers of cases with the described expression signatures are noted.