SDC1 and carcinoma: Independently from the localization, carcinoma with plasmacytoid morphology is characterized by diffuse proliferation of discohesive cells with plasmacytoid morphology, with eccentrically located nuclei, indistinct nucleoli, and eosinophilic cytoplasm that express cytokeratin (CK) and the transmembrane heparan sulfate proteoglycan CD138 (Syndecan-1) in over 50% of tumor cells [3–5].