primary localized retroperitoneal amyloid tumor with osseous meta plasia: case report and review of the literature

amyloidoma or amyloid tumor is a tumor-like localized deposit of amyloid encountered occasionally in association with multiple myeloma, various chronic inflammatory diseases and primary amyloidosis. amyloid tumors unassociated with plasmacytoma or other disease are extremely rare in soft tissues and few cases in various situations have been reported. histologic examination discloses amorphous eosinophilic material that stains positive with congo red preparation, and shows apple-green birefringence under polarized light. the deposits are surrounded by more or less prominent chronic inflammatory cells, especially plasma cells and giant cells. cartilage formation and ossification, however, occur in some amyloid tumors.