SOX10 is a member of the SRY-related HMG-box (SOX) family of transcription factors involved in the regulation of embryonic development and in the determination of cell fate. During development, SOX10 first appears in the forming neural crest and continues to be expressed in Schwann cells. It is important for differentiation, maturation and maintenance of Schwann cells and melanocytes. In normal tissues, SOX10 is expressed in Schwann cells and glial cells in the nervous system. It is also detected in melanocytes and epithelial cells of salivary gland and mammary gland. In tumor tissues, SOX10 labels melanoma and tumors of neural crest origin. A recent study reported the expression of SOX10 in basal-like, unclassified triple-negative breast carcinoma. Thus, breast carcinoma must be considered in the differential diagnosis of melanoma for a SOX10-positive metastatic malignant neoplasm.