a SPN cytology with branching fibrovascular cores and uniform, plasmacytoid tumor cells (H&E ×100). Although SPNs are low-grade tumors, they have potential to metastasize. b SPN in cell block. Papillary structures lined by monomorphic cells (H&E ×200). Nuclear beta-catenin positivity in tumor cells (inset: Beta catenin ×200).