Breast - nonmalignant
Benign tumors
Amyloid tumor

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

Revised: 4 October 2016, last major update October 2016

Copyright: (c) 2002-2016,, Inc.

PubMed Search: Amyloid tumor [title]

Cite this page: Amyloid tumor. website. Accessed October 22nd, 2016.
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’s 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, Waldenstrom’s macroglobulinemia)
    • AA type amyloidosis – chronic inflammatory disease (rheumatoid arthritis, Reiter’s 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
  • See diagram above
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
Micro 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)
Micro Images

Images hosted on PathOut servers:

Courtesy of Mark R. Wick, M.D.

Amyloid occurs
in lobule (lower left)
and as separate
stromal nodule
(upper right, AFIP)

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’s stain (Diagn Cytopathol 2003;28:325)
Cytology Images

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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