Mixed versus pure variants of desmoplastic melanoma: a genetic and immunohistochemical appraisal.

Desmoplastic melanoma is subclassified into pure and mixed variants with a higher rate of lymph node metastasis in the latter. Given that reasons for these biological differences are not currently known, we investigated these subtypes with techniques that included genetic and immunohistochemical analyses of 43 cases of desmoplastic melanoma (24 pure, 19 mixed). Direct DNA sequencing was performed on BRAFV600E, RET gene (coding region on exon 11) and KIT (exons 11, 13 and 17).

Lack of correlation between immunohistochemical expression of CKIT and KIT mutations in atypical acral nevi.

Background: Given the correlation between KIT mutations and immunohistochemical expression of CKIT in acral melanoma, our aim was to confirm the utility of CKIT detection as a screening tool for KIT genotyping in atypical acral nevi and to ascertain the frequency of KIT mutations in the same.

Design: Immunohistochemical staining for CKIT was performed and staining criteria were the following: negative = <10%, 1 = 11%-49%, and 2 = >50% of cells. Intensity grading was as follows: negative = 0, weak = 1, moderate = 2, and strong = 3.

Laser capture microdissection: methods and applications.

Laser microdissection is a nonmolecular, minimally disruptive method to obtain cytologically and/or phenotypically defined cells or groups of cells from heterogeneous tissues. It is a versatile technology and allows the preparation of homogenous isolates of specific subpopulations of cells from which RNA/DNA or protein can be extracted for RT-polymerase chain reaction (PCR), quantitative PCR, Western blot analyses, and mass spectrophotometry.

Somatic mutations in GNAQ in amelanotic/hypomelanotic blue nevi.

A recent study indicates that somatic mutations in codon 209 of GNAQ, a gene encoding the signaling protein G-protein α subunit q, may be present in up to 80% of blue nevi. Given that mutations in GNAQ represent dominant dark skin (Dsk) mutations caused by increased dermal melanin, the primary aim of this study was to ascertain whether amelanotic/hypomelanotic blue nevi exhibited somatic mutations in GNAQ like their melanotic counterpart. Genomic DNA was isolated for genotyping per protocol using techniques including laser capture microdissection to isolate nevus cells from amelanotic/hypomelanotic blue nevi (n = 8).

Molecular diagnostics-an emerging frontier in dermatopathology.

Advances made within the field of genomics and proteomics have facilitated the emergence of a new era of molecular diagnostics. However, ongoing rapid developments in molecular methodology ensure that this remains a complex field, accessible primarily to scientists who routinely utilize these techniques. For this reason, in this article we provide a concise overview of established and emerging molecular methods and discuss their role as diagnostic adjuncts in Dermatopathology.

Oncogenic BRAF-positive dysplastic nevi and the tumor suppressor IGFBP7--challenging the concept of dysplastic nevi as precursor lesions?

Oncogenic BRAF as an early and fundamental feature of melanocytic neoplasia has been confirmed with its identification in both melanoma and nevi. Oncogenic BRAF has been shown to induce senescence/apoptosis by up-regulating the tumor suppressor IGFBP7, which acts through autocrine/paracrine pathways to inhibit BRAF-MEK-ERK signaling. Given the putative neoplastic potential of dysplastic nevi, our aim was to ascertain in dysplastic nevi from intermittently sun-exposed skin and of varying severity the frequency of oncogenic BRAF and NRAS and to assess expression of IGFBP7 in the same.

Oncogenic BRAF and the tumor suppressor IGFBP7 in the genesis of atypical spitzoid nevomelanocytic proliferations.

Rare reports indicate that the frequency of BRAFV600E mutations is high in atypical Spitz nevi. The purpose of this study was to ascertain the utility of the RAF/RAS mutational status as a diagnostic adjunct in lesions with histologic features that deviate from a typical Spitz nevus and, to examine expression of Insulin growth factor binding protein 7 (IGFBP7), a tumor suppressor acting through autocrine/paracrine pathways to inhibit BRAF-MEK-ERK signaling, in the same. Genomic DNA for genotyping was isolated from 6 regular Spitz nevi and 14 atypical spitzoid nevomelanocytic proliferations (including 1 melanoma with spitzoid histomorphology).