Its sensitivity ranges between 93% and 100% in the published series, with a characteristic staining pattern in both the nucleus and cell cytoplasm; however, S100 is not highly specific, with it also being expressed by several soft tissue tumors (nerve sheath tumors, adipocytic tumors, chondroid tumors, notochordal tumors, and many others), hematopoietic disorders (Langerhans cell histiocytosis), and others tumors (glial tumors, sex cord-stromal tumors, myoepithelial carcinoma, and other salivary gland tumors) [17,18,19,20,21,22,23,24,25]. The gene discussed is S100B; the disease is Langerhans cell histiocytosis.