Miot, Luciane D. [UNESP]Miot, Hélio Amante [UNESP]Polettini, Jossimara [UNESP]Silva, Marcia Guimarães da [UNESP]Marques, Mariângela Esther Alencar [UNESP]2014-05-272014-05-272010-10-01American Journal of Dermatopathology, v. 32, n. 7, p. 676-682, 2010.0193-1091http://hdl.handle.net/11449/71892Melasma is a common acquired symmetrical hypermelanosis characterized by irregular light- to dark-brown macules on sun-exposed skin areas. The literature shows few studies on its physiopathogeny. However, changes in α-melanocyte stimulating hormone (α-MSH) secretion and melanocortin-1 receptor (MC1-R) expression may play a role to trigger this condition. Biopsies were taken from both melasma skin and adjacent perilesional normal skin of 44 patients. The biopsies were submitted for hematoxylin and eosin and Fontana-Masson staining and immunohistochemistry with Melan-A, α-MSH, and MC1-R, and processed for transmission electron microscopy. In some cases, they were submitted to MC1-R gene expression analysis by real-time polymerase chain reaction. Increased lymphohistiocytic infiltrate and solar elastosis, higher epidermal melanin were observed in melasma skin. Electron microscopy revealed a greater number of mature melanosomes in keratinocytes and melanocytes, and more prominent cytoplasmic organelles in melasma skin. There was no difference in melanocyte number between areas. However, melanocytes were larger and more dendritic in melasma skin. Immunohistochemistry with α-MSH and MC1-R showed significant labeling in melasmic epidermis but MC1-R messenger ribonucleic acid (RNAm) did not show significant quantitative difference between melasma and normal skin. © 2010 by Lippincott Williams & Wilkins.676-682engalpha-MSHimmunohistochemistrymelanosispolymerase chain reaction receptortype 1 melanocortinalpha intermedineosinhematoxylinmelan Amelaninmelanocortin 1 receptormessenger RNAcell organellechloasmaclinical articlecomparative studycontrolled studyelastosisgene expressionhumankeratinocytelymphocytic infiltrationmelanocytemelanosomemorphologypriority journalprotein expressionquantitative analysisreal time polymerase chain reactionskin biopsytransmission electron microscopyFemaleGene ExpressionHumansImage Processing, Computer-AssistedImmunohistochemistryMelanosisMicroscopy, Electron, TransmissionReceptor, Melanocortin, Type 1Reverse Transcriptase Polymerase Chain ReactionArtigo10.1097/DAD.0b013e3181cd4396Acesso restrito2-s2.0-779573780832543633050941005494079190953577575281169255191427528116925519142