Marker Protein Expression Combined With Expression Heterogeneity is a Powerful Indicator of Malignancy in Acral Lentiginous Melanomas

Patients and Methods: Samples of acral lentiginous melanomas (ALMs) were obtained from the Department of Pathology at Escola Paulista de Medicina—Universidade Federal de São Paulo (UNIFESP), São Paulo, Brazil. Demographic, clinical, and follow-up data were obtained from the charts of Hospital São Paulo. From 2 tissue microarrays containing 60 nevi and quadruplicate samples of ≥1.0-mm of 49 ALM, sections were stained to evaluate SCF, KIT, BRAF, CYCLIND1, MYC, and PTEN immunohistochemical protein expression. Results: Nevi and ALM from 2006 to 2010 were reviewed and collected. All specimens were in the vertical growth phase, and histopathological parameters indicated that tumors were at an advanced stage at diagnosis. Average tumor thickness was 6.95 mm, 63% were ulcerated, average mitotic index was 5 mitotic cells per mm2, and 43% were at Clark's level V. Compared with nevi, the χ2 test showed that ALM significantly correlated with SCF protein expression (P = 0.001) and expression heterogeneity (P

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