Breast - nonmalignant
Benign tumors / changes
Amyloid tumor

Author: Monika Roychowdhury, M.D., FCAP (see Authors page)

Revised: 3 August 2017, last major update October 2016

Copyright: (c) 2002-2017,, Inc.

PubMed Search: Amyloid tumor [title]

Cite this page: Amyloid tumor. website. Accessed October 19th, 2018.
Definition / general
  • Extracellular mass-like deposition of amorphous and insoluble proteins in an abnormal fibrillary configuration
Essential features
  • Extracellular deposition of acellular eosinophilic material in fat, stoma or blood vessels creating a mass effect
  • Stains positively for Congo red; metachromatic on Wright stain
  • May be localized or part of systemic amyloidosis
  • Treatment by complete excision
  • Amyloidosis in the breast first reported by Fernandez and Hernandez in 1973 (J Clin Pathol 2002;55:634)
  • Also called amyloidoma
  • Very rare
  • Usually women ages 45 - 79 years
  • 80% occur in right breast
  • Bilateral or unilateral but only rarely is confined to breast
  • Abnormal deposition of insoluble protein in an abnormal fibrillary configuration
  • Most common types are amyloid light chain (AL) and amyloid A (AA)
  • AL is caused by immunoglobin light chains and is secondary to plasma cell dyscrasia
  • AA is reactive amyloidosis and is secondary to chronic inflammatory disease
  • In vast majority of patients, breast amyloidosis is part of a systemic AL type disease (usually kappa light chain proteins)
  • It can be associated with malignancies of the breast
  • Depends on the type of amyloidosis:
    • AL type amyloidosis - plasma cell dyscrasia (myeloma, Waldenstr√∂m macroglobulinemia)
    • AA type amyloidosis - chronic inflammatory disease (rheumatoid arthritis, Reiter syndrome)
Diagrams / tables

Images hosted on other servers:

Figure 7: Flow chart for diagnosis of amyloidosis

Clinical features
  • Painless mass
  • May occur late in systemic disease
  • Complete physical examination needed to differentiate primary and secondary amyloid tumors
Radiology description
  • Visualized as mass on ultrasound and MRI
Radiology images

Images hosted on other servers:

Figures 1 and 2

Case reports
  • Excisional biopsy is successful if amyloid tumor is limited to the breast
Gross description
  • 5 cm or less, firm, gray white, opalescent
Microscopic (histologic) description
  • Amorphous eosinophilic extracellular deposits in fat, stroma or vessels
  • May cause ductal atrophy, form rings around individual fat cells, have associated multinucleated giant cell reaction or osseous metaplasia (J Clin Path 2002;55:634)
Microscopic (histologic) images

Images hosted on PathOut servers:

Courtesy of Mark R. Wick, M.D.

AFIP: amyloid occurs in
lobule (lower left) and
as separate stromal
nodule (upper right)

Thick wavy bands of
amyloid around lobular
glands and a nodular deposit
that is virtually acellular

Thioflavin T stain (left) and parenchyma - Congo red (right), courtesy of Mark R. Wick, M.D.

Images hosted on other servers:

Various images

Fig 2: H&E, Fig 3: Congo Red

Amyloid with osseous metaplasia

Cytology description
  • Amorphous acellular material with scattered plasma cells, lymphocytes, stromal cells and epithelial cells
  • Rare multinucleated giant cells
  • Metachromatic by modified Wright stain (Diagn Cytopathol 2003;28:325)
Cytology images

Images hosted on other servers:

Dense hyaline material and giant cells

Positive stains
  • Congo red (red orange with apple green birefringence under polarized light)
  • Metachromatic with crystal violet
Negative stains
Electron microscopy description
Differential diagnosis
  • Plasmacytoma: immature plasma cells, no amyloid
  • Stromal fibrosis: may have hyaline material but it has different histologic features from amyloid; also Congo red negative