Photodynamic Therapy with 5-aminolevulinic Acid 10% Gel and Red Light for the Treatment of Actinic Keratosis, Nonmelanoma Skin Cancers, and Acne: Current Evidence and Best Practices.

Photodynamic therapy (PDT) can be an effective treatment for actinic keratosis (AK) as well as selected non-melanoma skin cancers (NMSCs), such as Bowen's disease and superficial basal cell carcinoma. PDT has also demonstrated effectiveness in the management of acne vulgaris. Results from controlled clinical trials have shown the safety and efficacy of PDT for these conditions with the use of different photosensitizers and a wide range of light sources. PDT has been employed effectively as monotherapy and in combination with other topicals and alternate light or laser energy therapies. This article provides expert practical guidance for the use of the newest 5-aminolevulinic acid (ALA) product (ALA 10% gel) plus red light as monotherapy for AKs, NMSC, and acne. Here, information from clinical guidelines and a summary of supporting evidence is provided for each cutaneous condition. The authors also provide detailed guidance for employing ALA 10% gel, a photosensitizer precursor, for each of these applications.

Defective DNA mismatch repair activity is common in sebaceous neoplasms, and may be an ineffective approach to screen for Lynch syndrome.

A subset of individuals with Lynch syndrome (LS) has a variant called Muir-Torre syndrome (MTS) where patients develop multiple sebaceous neoplasms. Absence of gene expression and microsatellite instability (MSI) have been welldocumented in LS neoplasms. It is unclear whether the presence of these abnormalities in isolated sebaceous neoplasms would indicate the likely presence of otherwise unsuspected LS or MTS. 164 specimens of sporadic cutaneous sebaceous neoplasms were obtained. IHC was performed for expression of the DNA mismatch repair (MMR) genes MSH2 and MLH1. A 5-marker mononucleotide repeat microsatellite panel was analyzed to detect MSI, and two or more mutated markers were required for MSI. 164 sebaceous neoplasms were obtained from 162 patients. IHC data was successfully obtained from 162 samples and MSI data was obtained from 138 samples. 50/162 (31%) had abnormal IHC with loss of staining for either MSH2 (37/162, 23%), MLH1 (9/162, 5%) or both (4/162, 2%). 37% (52/138) of the tumors had MSI. 82% (111/136) of those with both IHC and MSI results correlated as expected. 18% (25/136) showed discordance between IHC and MSI. 69/163 (42%) had either abnormal IHC or MSI, indicating deficient DNA MMR activity. Given the substantial proportion of DNA MMR deficiency in these sebaceous neoplasms, screening for DNA MMR defects in sebaceous neoplasms would not appear to be an effective way to distinguish patients with LS or MTS from those with sporadic skin lesions and an ordinary risk of cancer.