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Tretinoin cream has been used extensively to reverse the changes of photoaging. It is the first topical therapy to undergo controlled clinical testing and proved to be efficacious. These results have been substantiated with photography, histopathologic examination, and skin surface replicas. The mechanism of action of retinoic acid is unknown, but it may bind to a specific receptor that alters the gene expression of the cell. Therapy is most successful when a liberal amount of tretinoin 0.1% cream is applied to the skin daily. Tretinoin cream has an excellent safety record; a local cutaneous hypervitaminosis A reaction is the only common problem.

In a double-blind study, 20 patients with oral lichen planus were treated twice daily with 0.1% isotretinoin gel or the vehicle alone for two months. Subsequently, patients who used the placebo received the active preparation for another two months. Patients treated with the active medication displayed significantly greater improvement than patients receiving the placebo. Patients who were treated initially with the placebo showed statistically significant improvement after receiving the topical isotretinoin treatment for two months. Side effects from using the gel were primarily a transient burning sensation or irritation on initial application.

In this study, we employed a high-frequency ultrasound system to measure the epidermal thicknesses of psoriasis plaques and normal skin in vivo. Eighty-four percent of the ultrasound measurements fell within the range of epidermal thickness determined by histology. The average thickness of untreated psoriasis measured by ultrasound was significantly greater than that of either treated psoriasis or normal skin. Ultrasound measurement of thickness was consistent with clinical assessment. Ultrasound measurements also demonstrated known variations in epidermal thickness by body site. Further development is needed to obtain measurements that are fully representative of the epidermis.

A patient with both pili torti and leukonychia had a family history indicating dominant inheritance for the nail changes. However, no relatives had hair abnormalities. The authors briefly review both of these unusual entities.

The recent findings that the immunosuppressant cyclosporine A (CsA) improves psoriasis raises the possibility that cellular immune processes play a major role in the pathogenesis of psoriasis. We therefore investigated the phenotype and function of cells within psoriatic epidermis that can play a role in cellular immunologic reactivity. Double fluorescence microscopic studies with monoclonal antibodies of epidermal cells in suspension (EC) and of histologic sections demonstrated that involved psoriatic skin contained a significantly increased number of non-Langerhans cell T6-DR+ EC (4.9 + 2.1%) relative to uninvolved (0.3 +/- 0.1%), p less than 0.01. This non-Langerhans cell population was comprised of DR+ monocytes, DR+ activated T lymphocytes, a few DR+RFD1+ antigen-presenting cells (APC), and DR+ keratinocytes. Langerhans cell (LC) levels in EC suspension were not different between involved and uninvolved psoriatic epidermis. Functional studies demonstrated that involved psoriatic epidermal cells had an increased capacity to induce T-cell activation and proliferation relative to uninvolved EC (p less than 0.04). This increased APC activity was due to the non-LC T6-DR+HLe1+ APC population and not to DR+ keratinocytes. These results demonstrate that involved psoriatic epidermal cells contain both an increased number and function of antigen-presenting cells. The pathogenetic mechanisms in psoriasis may be related to ongoing cellular immune responses in the skin, and the effect of CsA may be mediated through a suppressive effect on the enhanced antigen-presenting cell activity.