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Melanin is a granular brown-black pigment unevenly distributed in tissues. Severe melanin deposition can obscure cellular morphological features and tissue structures, hindering the evaluation of melanocytic lesion. This condition is particularly prone to interfering with the evaluation of immunohistochemistry (IHC), thereby affecting diagnostic accuracy. Therefore, melanin bleaching techniques have become a crucial step, enabling pathologists to better examine melanin-rich tissue specimens. In this study, we utilized low-concentration 1 % hydrogen peroxide for melanin bleaching and integrated the bleaching process into IHC on the same platform to establish a continuous workflow. We compared melanin bleaching in different steps to see the effect of bleaching on IHC. Three different bleaching protocols were designed: bleaching (i) before antigen retrieval, (ii) after antigen retrieval, and (iii) after IHC staining. The effects of melanin bleaching on tissue morphology preservation and IHC quality in heavily pigmented melanocytic lesions were evaluated. The results showed that melanin bleaching before antigen retrieval ensured accurate localization of expression of HMB45, Melan A, and SOX10. This method showed no background staining, preserved tissue morphology without detachment, and maintained antigen immunogenicity. The pre-retrieval bleaching protocol allowed for clearer IHC staining result and can be applied on automated platform and routine staining workflows.
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http://dx.doi.org/10.1016/j.prp.2025.156047 | DOI Listing |
Sci Rep
August 2025
Shengli Clinical Medical College, Fujian Medical University, Fuzhou, 350001, Fujian Province, China.
Melanin granules may be difficult to distinguish from the brown reaction product of 3,3'-diaminobenzidine (DAB) in immunostaining. To identify a reliable immunostaining protocol for pigmented melanoma that preserves tissue integrity while enabling clear observation of antigen-antibody binding. Ki67 and the human melanoma black 45 (HMB45) immunostaining was performed on 30 pigmented melanoma specimens using three methods: (1) Unbleached control, (2) Bleached with 5% H₂O₂, (3) Alkaline Phosphatase-3-Amino-9-Ethylcarbazole (AP-AEC).
View Article and Find Full Text PDFZhonghua Bing Li Xue Za Zhi
July 2025
Precision Pathology Diagnosis Center, Weifang People's Hospital, Weifang 261000, China.
To establish a rapid and effective melanin-bleaching method to standardize and improve the molecular pathological analyses of melanoma. Fifteen cases of melanoma with melanin content exceeding 50% collected at the Precision Pathology Diagnosis Center, Weifang People's Hospital, Weifang, China between 2023 and 2024 were included in the study. These tissue samples were subject to melanin-bleaching treatments using HO, potassium permanganate (KMnO), Tris-HCl or PBS method.
View Article and Find Full Text PDFPathol Res Pract
July 2025
Department of Pathology and Laboratory Medicine, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan; Shu-Zen Junior College of Medicine and Management, Kaohsiung, Taiwan; School of Medicine, College of Medicine, National Sun Yat-Sen University, Kaohsiung, Taiwan. Electronic address: jbliao@gmail
Melanin is a granular brown-black pigment unevenly distributed in tissues. Severe melanin deposition can obscure cellular morphological features and tissue structures, hindering the evaluation of melanocytic lesion. This condition is particularly prone to interfering with the evaluation of immunohistochemistry (IHC), thereby affecting diagnostic accuracy.
View Article and Find Full Text PDFJ Racial Ethn Health Disparities
March 2025
University of Michigan, Ann Arbor, MI, USA.
Colorism, first conceptualized by writer and activist Alice Walker in 1982, is a byproduct of racism that refers to discrimination based on skin tone, hair texture, and facial features. Although less studied than race-based discrimination-which typically involves negative attitudes and unfair treatment of individuals based on their racial identity, usually propagated between racial and ethnic groups-colorism is a critical area of research that provides insight into health disparities occurring within racial and ethnic groups. This narrative literature review assesses the extent to which colorism's impact on global health outcomes has been studied.
View Article and Find Full Text PDFHistol Histopathol
February 2025
Department of Basic Medical Sciences, The 960th Hospital of PLA, Tianqiao District, Jinan, Shandong, PR China.
In this study, two chromogenic systems, horseradish peroxidase (HRP)-3,3'-diaminobenzidine (DAB) and HRP-3,3',5,5'-tetramethylbenzidine (TMB), were used to perform single-color and double-color immunohistochemical staining (sIHC and dIHC, respectively) on multiple antigens in four distinct tissue types. The chromogenic results of the HRP-TMB system exhibited a vibrant blue-green color, and the tissue localization and signal intensity were consistent with those of the HRP-DAB system. In addition, it demonstrated clear differentiation from the hematoxylin-stained nucleus, endogenous melanin, and brown chromogenic results of HRP-DAB.
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