[Relevance of histological examination in the diagnosis of autoimmune bullous dermatoses]

Clinical, histological and immunpathological findings in 32 patients with dermatitis herpetiformis Duhring

BACKGROUND

Dermatitis herpetiformis is a chronic severely pruritic dermatosis. It is a cutaneous manifestation of celiac disease. The aim of our study was to collect clinical, histological and immunopathological data on patients who were treated in the University Departments of Dermatology in Würzburg and Lübeck from 1996 to 2008.

PATIENTS AND METHODS

We retrospectively analyzed 32 patients. Only patients with positive findings on direct immunofluorescence microscopy were included in this study.

RESULTS

All patients demonstrated skin lesions in the predilection areas of knees, elbows, gluteal region and scalp. The male to female ratio was 1.5 : 1 and the average age was 43 years. The interval between the first symptoms and diagnosis ranged from 6 weeks to 20 years. Direct immunofluorescence microscopy showed that granular IgA deposits were more often found continuously along the dermal-epidermal junction rather than focally in the tips of the dermal papillae. Results of small intestinal biopsies were available from 29 patients and confirmed the presence of celiac disease in all cases. None of the patients reported gastrointestinal symptoms. IgA antibodies against tissue transglutaminase and epidermal transglutaminase were found in 88% and 94% of patient sera, respectively.

CONCLUSIONS

The detection of IgA autoantibodies against epidermal transglutaminase is the most sensitive serological test in the diagnosis of dermatitis herpetiformis. Our observations confirm that patients with dermatitis herpetiformis usually do not demonstrate apparent gastrointestinal symptoms.

Histopathology of anti-laminin 5 mucous membrane pemphigoid

BACKGROUND

Anti-laminin 5 mucous membrane pemphigoid (MMP) is an autoimmune blistering disease characterized by autoantibodies against the major basement membrane component laminin 5 (laminin 332, epiligrin).

OBJECTIVE AND METHODS

We reviewed 17 biopsy specimens from 9 patients with anti-laminin 5 MMP in an attempt to define typical histopathologic features of the disease.

RESULTS

Fifteen specimens showed subepidermal blister formation, while two biopsy specimens revealed an epithelial ulcer. In 11 biopsies a sparse to moderate inflammatory infiltrate composed of lymphocytes and neutrophils with some eosinophils was observed. Four biopsies showed a dense infiltrate dominated by neutrophils in two cases and by eosinophils in one case. The remaining biopsy revealed a dense lymphoplasmacellular infiltrate without granulocytes. Scarring of the upper dermis was present only in 5 specimens. Immunohistochemical analysis localized type IV collagen to the dermal side of the blister, suggesting that split formation occurred within the lamina lucida of the cutaneous basement membrane.

LIMITATIONS

The number of patients studied was relatively small.

CONCLUSIONS

Histopathology of anti-laminin 5 MMP is characterized by subepidermal blistering and a sparse to moderate superficial lymphohistiocytic infiltrate with neutrophils and/or eosinophils. Both infiltrate density and composition may vary, making anti-laminin 5 MMP indistinguishable from other autoimmune subepidermal blistering diseases by histopathology alone. Scarring is present only in a minority of cases and is not a sensitive clue to the diagnosis of anti-laminin 5 MMP.

Immunopathology and molecular diagnosis of autoimmune bullous diseases

Autoimmune bullous diseases are associated with autoimmunity against structural components maintaining cell-cell and cell matrix adhesion in the skin and mucous membranes. Pemphigus diseases are characterized by autoantibodies against the intercellular junctions and intraepithelial blisters. In pemphigoid diseases and epidermolysis bullosa acquisita, sub-epidermal blistering is associated with autoantibodies targeting proteins of the hemidesmosomal anchoring complex. The autoantigens in autoimmune blistering diseases have been extensively characterized over the past three decades. In general, the pathogenicity of autoantibodies, already suggested by clinical observations, has been conclusively demonstrated experimentally. Detection of tissue-bound and circulating serum autoantibodies and characterization of their molecular specificity is mandatory for the diagnosis of autoimmune blistering diseases. For this purpose, various immunofluorescence methods as well as immunoassays, including immunoblotting, enzyme-linked immunosorbent assay and immunoprecipitation have been developed. This review article describes the immunopathological features of autoimmune bullous diseases and the immunological and molecular tests used for their diagnosis and monitoring.

Histopathology of Anti-p200 Pemphigoid

Anti-p200 pemphigoid is an autoimmune subepidermal blistering disease characterized by circulating and tissue-bound antibodies against a 200-kd glycoprotein (p200) of the human dermis. We reviewed 10 lesional biopsies from seven patients with anti-p200 pemphigoid in an attempt to define typical histopathologic features of this disease. All biopsy specimens showed subepidermal blistering and a moderate to dense inflammatory infiltrate in the upper dermis. Immunohistochemical analysis localized type IV collagen to the dermal side of the blister, suggesting that split formation occurred within the lamina lucida of the cutaneous basement membrane. The inflammatory infiltrate was composed almost exclusively of neutrophils in six biopsies and contained a mixture of neutrophils and eosinophils in the remaining four. In three specimens, microabscess formation in the papillary dermis adjacent to the blister cavity was noted. Neutrophilic and eosinophilic spongiosis was found in five and three biopsies, respectively. We conclude that histopathology of anti-p200 pemphigoid is characterized by subepidermal blistering and a superficial inflammatory infiltrate, which is usually dominated by neutrophils but occasionally contains significant numbers of eosinophils. While this microscopic picture mimics that of linear IgA disease, dermatitis herpetiformis, or bullous pemphigoid, it should also alert a histopathologist to the possibility of anti-p200 pemphigoid and prompt immunofluorescence and immunoblotting studies for definite diagnosis or exclusion of this autoimmune subepidermal blistering disease.