Immunohistochemical detection of V600E BRAF mutation is a useful primary screening tool for malignant melanoma.

BACKGROUND: We compared the use of an immunohistochemical (IHC) method using a monoclonal antibody to BRAF V600E (which detects the main BRAF mutation) with existing DNA probe screening in tissue samples from 71 patients with malignant melanoma. MATERIALS AND METHODS: Paraffin blocks were cut to provide consecutive slides for haematoxylin and eosin staining, and for known positive micro-array DNA control material. IHC was performed by the Optiview detection system. All slides were scored independently by the clinical lead and the laboratory lead using a positive/negative system. RESULTS: The DNA method found 26 samples to be positive, the IHC found 21 to be positive, giving a sensitivity value for IHC of 80.8%. However, all of the 45 samples found to be negative by DNA were also negative by IHC, giving a specificity of 100%. There were 66 instances of full agreement, giving a concordance of 93%. Together, these data give a kappa statistic of 0.843, indicating very good agreement. CONCLUSION: The data reveal a very close link between the two methods, supporting the use of the V600E as a primary screen for BRAF mutations in malignant melanoma. Samples found to be negative by this method may be retested by the DNA probe method. IHC detection conserves patient DNA from tumour blocks as only one section is required to perform the assay. The V600E antibody method is considerably cheaper and faster than the DNA probe assay, with a turn-around time of 24-48 hours, enabling more rapid clinical management.

Use of a novel 1-hour protocol for rapid frozen section immunocytochemistry, in a case of squamous cell carcinoma treated with Mohs micrographic surgery.

For squamous cell carcinoma (SCC) treated using Mohs micrographic surgery (MMS), interpretation of haematoxylin and eosin-stained frozen sections can be challenging. In these situations, ancillary use of immunostaining is a useful tool for the Mohs surgeon. However, use of immunostaining in MMS laboratories is limited, mainly because current manual immunostaining platforms are subject to operator error, and automated immunostaining, albeit accurate, is too slow for inclusion in MMS. In this report, we describe a novel 1-hour protocol for rapid frozen section immunocytochemistry, using the pancytokeratin markers AE1/AE3. This protocol has been specifically designed to integrate the speed of manual techniques and the accuracy of automated platforms, making it a valuable addition to the MMS laboratory. We propose that in selected or histologically challenging cases, there is a role for the use of this novel protocol, allowing the Mohs surgeon to more confidently declare tumour clearance, thus preventing further unnecessary surgery and preserving healthy tissue.