BCC specimens (formalin-fixed paraffin-embedded blocks) from MMS that had been stored in the pathology archive of Korea University Ansan Hospital were used. In preparing the tissue slides, we targeted the mostly pigmented area of the BCC specimen in the gross section. Tissue sections were made with the most pigmented part at a thickness segmentation of 4 µm.
Hematoxylin-eosin stained slides were reviewed collaboratively by board-certified pathologists and dermatologists to confirm the histopathologic diagnosis of BCC and subtype. Special staining for the identification of melanin pigment was performed using the Fontana–Masson stain. Immunohistochemical staining with Melan-A/MART-1 (clone A103, concentrated; Agilent Technologies) and HMB-45/Melanosome (clone HMB-45, concentrated; Agilent Technologies) was performed to stain melanocytes and melanophages. Primary antibody incubation (room temperature) was performed in a moist chamber for 3 hours using Dewax and Hier Buffer H (Thermo Scientific). For standardization, all stains were performed on the same date, under the same conditions, and by the same technician.
Hematoxylin-eosin stained slides were reviewed collaboratively by board-certified pathologists and dermatologists to confirm the histopathologic diagnosis of BCC and subtype. Special staining for the identification of melanin pigment was performed using the Fontana–Masson stain. Immunohistochemical staining with Melan-A/MART-1 (clone A103, concentrated; Agilent Technologies) and HMB-45/Melanosome (clone HMB-45, concentrated; Agilent Technologies) was performed to stain melanocytes and melanophages. Primary antibody incubation (room temperature) was performed in a moist chamber for 3 hours using Dewax and Hier Buffer H (Thermo Scientific). For standardization, all stains were performed on the same date, under the same conditions, and by the same technician.