Evidence behind the use of molecular tests in melanocytic lesions and practice patterns of these tests by dermatopathologists.

BACKGROUND: The gold standard for the diagnosis of melanocytic lesions is histologic examination. However, as histologic examination can have its limitations, there are many clinical scenarios in which additional testing may be appropriate in an attempt to render a definitive diagnosis. METHODS: A literature review for three ancillary tests-comparative genomic hybridization (CGH)/single-nucleotide polymorphism (SNP) array, fluorescence in situ hybridization (FISH), and gene expression profiling by quantitative reverse transcription polymerase chain reaction (qRT-PCR)-was compiled and current use patterns were tabulated. Survey of the practice patterns of these tests by dermatopathologists was also accessed in the attendees of the American Society of Dermatopathology Annual Meeting (Chicago, 2016). RESULTS: Here we summarize the use of these molecular tests in melanocytic lesions. We found that 54.4% of the respondents surveyed utilize (or expect consultants to utilize) molecular testing of melanocytic lesions in their practice when appropriate. CONCLUSIONS: CGH/SNP arrays, FISH testing, and qRT-PCR applied to melanocytic lesions have allowed for more accurate classification. Just over half of those surveyed use molecular testing for melanocytic lesion with the majority sending their cases out for completion of the molecular test.

[Melanocytoma and meningeal melanocytosis, similar but different lesions]. / Melanocitoma y melanomatosis meníngea, lesiones similares pero diferentes.

BACKGROUND: Meningeal melanomatosis is an extra-axial well-encapsulated malignant tumour with diffuse meningeal growth and dark coloration (due to high melanin contents), while meningeal melanocytoma is the focalized benign variant. Melanocytic lesions may be secondary to melanoma or be histologically benign, however, their diffuse nature makes them impossible to cure. Melanocytosis is a diffuse tumour that can form solitary extra-axial tumours, which invades the parenchyma and presents signs of malignancy with increased mitosis and Ki67, observed in 1 to 6% of immunopathological exams. Melanoma of the leptomeninges, presents signs of malignancy with anaplastic cells, which cluster in fascicles of melanin in the cytoplasm, with more than 3 atypical mitoses per field and Ki67 presenting in more than 6% of the immunopathological fields analysed. CLINICAL CASE: We present the case of a patient with long-term meningeal melanomatosis, with progressive neurologic deficit and characteristic radiologic features, and another case of meningeal melanocytoma. CONCLUSIONS: Benign melanocytic neoplasms of the central nervous system must be treated aggressively in the early phases with strict follow-up to avoid progression to advanced phases that do not respond to any treatment method. Unfortunately, the prognosis for malignant melanocytic lesions is very poor irrespective of the method of treatment given.