When the immunoprofile is not consistent with that of common spindle cell tumors, immunostaining for FDC markers such as CD21, CD23, and CD35, as well as further immunohistochemistry for D2-40, CD68, EGFR, EBV, and BRAF can be helpful for the diagnosis and subtyping of FDCS. The gene discussed is PDPN; the disease is spindle cell neoplasm.