Dermatoscopic and immunohistochemical features of diagnostics of the dysplastic nevi

Анотація

Dysplastic nevi (DN) are the subject of debates between clinicians and pathologists. There is no standard diagnostic and treatment approach and this causes many disagreements. There is a need to study an immunohistochemical marker PTEN as a long-range diagnostic mechanism between early-stage melanoma and dysplastic nevi. A search for correlations between other markers (Ki-67, SOX-10, p16, PTEN) and dermatoscopic criteria was conducted. We observed 95 cases of clinically atypical melanocytic tumors in adult patients aged 18-65 years. We determined 13 dermatoscopic criteria that accompany atypical melanocytic formations such as structureless areas, irre­gular globules, atypical pigment network, gray dots, blotches, blue-white veil, negative pigment network, polymorphous vessels, “starburst” pattern, angulated lines, multiple colors, regression structures, pseudopods. During  the study all obtained lesions were removed with the following pathology and immunohistochemistry. The use of immunohistochemical markers made it possible to separate early melanomas (n=19) and other (benign) tumors (n=22) from the primary cohort of patients who, according to the results of pathology, had moderate or severe grade of dysplasia. The most common dermatoscopic feature were structureless areas combined with other mentioned signs. The presence of PTEN expression in benign melanocytic tumors and the absence of PTEN in a primary cutaneous melanoma confirms its role in melanoma pathogenesis. In melanoma, along with other markers, SOX-10 expression indicates aggressiveness, atypia, and archi­tectural disorders. Dysplastic nevi usually retain p16, which helps distinguish them from melanoma. The relatively low level of Ki-67 expression in dysplastic nevi is a criterion that helps to distinguish them from melanoma. We consider that application of this combination of immunohistochemical markers in routine practice can significantly improve the diagno­sis of dysplastic nevi and melanoma, especially for diagnostic collisions among superficial atypical melanocytic proli­ferations. Usage of the phosphatase and tensin homolog protein can be useful for diagnostic not only group of “thin mela­nomas” but for non-pigmented nodular melanomas and for secondary metastatic melanoma lesions with unknown primary tumors.