Linear IgA bullous dermatosis

Linear IgA bullous dermatosis (LABD) is group of heterogeneous autoimmune subepidermal blistering diseases characterized by exclusively IgA autoantibodies targeting a component of the epidermal basement membrane zone. The laminina-lucida-type LABD, also known as chronic bullous dermatosis of childhood, is a rare disease, yet the most common autoimmune blistering disease among childeren with a peak incidence at 4-5 years of age. The major target antigens in laminina-lucida-type LABD are 120 kDa LAD-1 antigen, and its carboxyterminal proteolysed form 97 kDa LABD antigen 1 (LABD97). Both proteins are produced by cleavage of the extracellular domain of BP180, one of the main structural components of the hemidesmosome. The autoantigen targeted by IgA in the sublamina densa-type LABD, also known as IgA epidermolysis bullosa acquisita, is type VII collagen. In adults, LABD may also be drug-induced.</p

IgA pemphigus

IgA pemphigus (IGAP) is a rare variant of pemphigus characterized by tissue-bound and circulating autoantibodies exclusively from the IgA class against desmosomal and non-desmosomal proteins of the epidermis. Based on the clinics, histology, direct immunofluorescence and autoantibody profile it is classified in two types: the subcorneal pustulosis dermatosis (SPD) type and the intraepidermal neutrophilic IgA dermatosis (IEN) type. The first line therapy is dapsone.</p

Dermatological examination of bullous diseases

Physical examination in bullous diseases always comprises looking at skin and mucous membranes. Examine the skin not only for the presence of vesicles or bullae but also for other efflorescence's and typical distribution pattern. Nikolsky sign tests the resilience of the healthy-lookig skin. The mucous membranes of mouth, nose, eyes and genitals need to be examined systematically. Disease activity and extent of skin and mucous membranes can be assessed using disease activity outcome measures that are validated for pemphigus, bullous pemphigoid and mucous membrane pemphigoid.</p

Dermatitis herpetiformis

Dermatitis herpetiformis (DH) is the specific skin manifestation of coeliac disease (CD) caused by the digestion of gluten in HLA-DQ2 or HLA-DQ8 individuals. DH is characterized by intensely pruritic polymorphic papulovesicular eruption on the extensor surfaces of the body. Both diseases are characterized by circulating IgA autoantibodies against tissue transglutaminase (tTG), which bind to the smooth muscle layer of the monkey esophagus causing the so-called EMA positivity. Additionally DH patient have another autoantibody population targeting the epidermal transglutaminase (eTG), the autoantigen of DH, which protein is highly homologous to tTG.</p

Epidermolysis bullosa acquisita

Epidermolysis bullosa acquisita (EBA) is a subtype of pemphigoid that may present with scarring similar to hereditary dystrophic epidermolysis bullosa, of which the naming of EBA was derived. The clinical subtype of EBA with scarring is named mechanobullous EBA, because blisters are evoked by sudden mechanical trauma to the skin. The other subtype of EBA with erythematous lesions without scarring is named inflammatory EBA, and may look like bullous pemphigoid. The mucous membranes can be involved in both subtypes. The pathogenesis is mediated by IgG or IgA against type VII collagen, which is the component of anchoring fibrils below the lamina densa. Diagnosis is confirmed by detection of a u-serrated linear pattern of immune depositions by direct immunofluorescence microscopy of a skin biopsy. The pathogenesis of both clinical subtypes is unknown, and is not related to binding of a particular epitope of the auto-antigen. EBA is associated with systemic lupus erythematosus and colitis ulcerosa. The disease is relative refractory to treatment.</p

Bullous systemic lupus erythematosus

Bullous systemic lupus erythematosus (BSLE) is rare heterogeneous cutaneous manifestation in patient with systemic lupus erythematosus (SLE). BSLE encompasses a subepidermal autoimmune bullous disease with type VII collagen autoantibodies, leading to epidermolysis bullosa acquisita in patients with SLE. Alternatively, an acute generalized hemorrhagic vesiculo-bullous eruption may also occur in patients with SLE caused by the extensive inflammatory reaction without the presence of type VII collagen. Vesicular eruptions can also be seen in subacute cutaneous lupus erythematosus due to severe inflammatory reaction with subepidermal clefting, which in extreme cases may resemble erythema multiforme (Rowell syndrome) or toxic epidermal necrolysis.</p

Bullous dermatitis artefacta

Bullous dermatitis artefacta is a psychodermatologic disorder in patients who mimic skin disease by inflicting themselves blisters. The diagnosis is often apparent at first visit. The diagnosis should never be immediately revealed to the patient. Instead a serious, yet limited, workup is advised, while developing a trustful patient-doctor relation. The strategy is to give the patient the impression you know it was self-inflicted, but leaving an escape for clearance by trivial causes imagined by the patient such as avoiding drinking coffee (narrow escape). In refractory cases, when confrontation becomes unavoidable, dual approach by dermatologist and psychiatrist is necessary.</p

Learning effective color features for content based image retrieval in dermatology

We investigate the extraction of effective color features for a content-based image retrieval (CBIR) application in dermatology. Effectiveness is measured by the rate of correct retrieval of images from four color classes of skin lesions. We employ and compare two different methods to learn favorable feature representations for this special application: limited rank matrix learning vector quantization (LiRaM LVQ) and a Large Margin Nearest Neighbor (LMNN) approach. Both methods use labeled training data and provide a discriminant linear transformation of the original features, potentially to a lower dimensional space. The extracted color features are used to retrieve images from a database by a k-nearest neighbor search. We perform a comparison of retrieval rates achieved with extracted and original features for eight different standard color spaces. We achieved significant improvements in every examined color space. The increase of the mean correct retrieval rate lies between 10% and 27% in the range of k=1–25 retrieved images, and the correct retrieval rate lies between 84% and 64%. We present explicit combinations of RGB and CIE-Lab color features corresponding to healthy and lesion skin. LiRaM LVQ and the computationally more expensive LMNN give comparable results for large values of the method parameter κ of LMNN (κ≥25) while LiRaM LVQ outperforms LMNN for smaller values of κ. We conclude that feature extraction by LiRaM LVQ leads to considerable improvement in color-based retrieval of dermatologic images