Aeroallergens and food allergens are able to elicit eczematous skin reactions after epicutaneous application. As no gold standard for aeroallergen provocation in AE exists, the relevance of aeroallergens for AE flares may be evaluated by APT in addition to SPT and sIgE. The data may contribute to the international standardization of the APT.

An elevated basal serum tryptase as well as mastocytosis are risk factors for severe or even fatal shock reactions to Hymenoptera stings. Although the efficacy of venom immunotherapy in these patients is slightly reduced, most of them can be treated successfully. Based on currently available data, lifelong treatment has to be discussed in this situation.

Lentigo maligna (LM) is an in situ melanoma which usually occurs in sun-damaged skin on the head and neck of elderly patients. Depending on the anatomical site and its size treatment of LM can be problematic and usually includes surgical excision or radiotherapy. Recent reports indicate that topical imiquimod may be an effective treatment. However, no data on the underlying immune response in the skin during treatment of LM with topical imiquimod are available so far. We report a 62-year-old caucasian woman with a histologically verified LM which was successfully treated with topical imiquimod 5% cream. Skin biopsy specimens were obtained before, during (at week 10) and 4 weeks after cessation of topical treatment with imiquimod 5% cream. Histological and immunohistochemical examination was performed in order to detect residual atypical melanocytes and to characterize the inflammatory infiltrate. A complete clinical and histological clearance of the skin lesion was achieved, with no recurrence up to 9 months after the end of treatment. During topical application of imiquimod 5% cream a depletion of epidermal and dermal CD1a+ dendritic cells was observed. The inflammatory infiltrate consisted of CD68+ macrophages and mainly of CD3+ T cells with a slight predominance of CD8+ T cells. An enhanced expression of granzyme B and TIA-1 was also noted particularly in the epidermis and near the dermoepidermal junction. In conclusion, our data indicate that imiquimod 5% cream induces a cytotoxic T-cell-mediated immune response in situ which may account for the complete destruction of the malignant melanocytes in LM. Further clinical trials and longer follow-up periods on the use of imiquimod for LM are warranted.

Mast cell chymase is a chymotrypsin-like serine proteinase primarily stored in secretory mast cell granules. Mast cell chymase has various effects on angiotensin, metalloproteases, lipoproteins, procollagen, neuropeptides and cytokines. Recent studies have demonstrated that chymase inhibitors inhibit skin inflammation. In this study we sought to determine the role of mast cell chymase in atopic dermatitis (AD) in comparison with its role in psoriasis and normal skin. Skin biopsy specimens were obtained from non-lesional and lesional skin of patients with chronic AD and psoriasis and from normal skin of non-atopic and non-psoriatic controls. The number of mast cells containing chymase was determined by immunohistochemistry using a chymase-specific monoclonal antibody. A significantly (P<0.05) enhanced number of chymase-positive cells was found in lesional AD skin as compared to normal skin as well as to lesional and non-lesional skin of patients with psoriasis. A significant (P<0.05) increase in the number of chymase-positive cells was also found in non-lesional AD skin in comparison to psoriasis. An enhanced, albeit not statistically significant difference was noted in non-lesional AD skin as compared to normal skin. In conclusion, these results suggest that mast cell chymase may play an integral part in eliciting and maintaining cutaneous inflammation in AD but not in psoriasis. The increased proteinase activity of mast cell chymase may also be involved in promoting a skin barrier defect in AD, which subsequently enhances the skin's permeability to allergens and microbes and thereby aggravates the eczema.