Amyloidosis or aggregation and deposition of the amyloid protein (beta-pleated sheets) can be identified by using an amyloid stain on bone marrow biopsy specimens. Several different proteins can be converted to amyloid, including serum amyloid A protein and immunoglobulins. Amyloidosis involving the bone marrow is most commonly seen in patients that have a diagnosis of multiple myeloma. Amyloid deposits are most commonly identified on core biopsy specimens, but may also be seen on aspirate smears. The amyloid deposits usually occur within blood vessels walls of the bone marrow biopsy sections. Amyloid can be identified with the hematoxylin & eosin (H&E) stain as waxy, homogenous, eosinophilic material. Amyloid can also be identified with the Wright stain as a waxy, pink to dark purple cellular mass appearance. Most commonly, amyloid can be identified with the Congo red stain as an "apple-green birefringence" when viewed under polarized microscopic light. Additionally, other stains may be used to identify amyloid such as crystal violet or thioflavin T.