CD99 and neoplasm: The “gold-standard” diagnosis of metastatic spinal MCS relies on pathological findings.[14,15] Under light microscope, the tumor has a bi-directional differential feature which consists of undifferentiated small-round mesenchymal cells and islands of hyaline cartilage.[14,15] Immunohistochemistry of biomarkers such as Vimentin, S-100, CK, CD99, NSE, CD56, CD34, and FL1 may help us to differentiate this entity from other spinal tumors.[14,15]