CD99 and mesenchymal cell neoplasm: Other immunomarkers, such as CD99, were mentioned in the literature, with variable marking, and without diagnostic relevance.27,39,49,60 The need for an IHC panel with negative markers, such as S100, AE1/AE3, desmin, CD31, and CD68, aims to help in the differential diagnosis in relation to other mesenchymal and non-mesenchymal tumors.23,27,59