Amyloid deposits may be seen in about 25% of extraosseous plasmacytomas. They appear as pink amorphous deposits with scattered multinucleated foreign body giant cells in the background. In contrast to solitary plasmacytoma of bone, only about 15% of extraosseous plasmacytomas progress to multiple myeloma. The treatment usually consists of local irradiation. Recurrences or spread to regional lymph nodes may be seen in 15% to 25% of cases. Rare cases may metastasize to distant sites.