A screening mammogram in a 68-year-old with a history of idiopathic thrombocytopenic purpura (ITP) showed coarse heterogeneous calcifications in the right breast at 1200 (A, B). Stereotactic biopsy returned negative for malignancy, showing amyloid deposits associated with microcalcifications.
Amyloidosis is characterized by systemic or localized deposition of abnormally folded proteins, or amyloid, in the extracellular tissue matrix. Systemic amyloidosis includes primary amyloidosis (AL) caused by the deposition of immunoglobulin light chain associated with plasma cell neoplasms and secondary amyloidosis (AA) that is associated with chronic inflammatory and autoimmune conditions.1
Amyloid deposition in the breast is exceptionally rare and is most commonly a manifestation of underlying breast cancer, B-cell lymphoproliferative disorders, plasma cell dyscrasias, or other systemic inflammatory processes. A large amyloid center in Boston reported that only 0.5% of patients presented with localized amyloidosis, all of which had microcalcifications largely within the breast lobule.2 The Mayo Clinic reported 40 cases seen over 16 years, 47% of which had systemic amyloidosis, mainly of the AL type and likely originating from infiltrative plasma cells secreting immunoglobulins.1
Mammary amyloidosis typically presents on screening mammography as microcalcifications, asymmetry, and/or a palpable mass. Histologic examination, showing apple-green birefringence under polarized light when stained with Congo red, is essential to confirm the diagnosis of amyloidosis. When identified, a work-up for possible hematologic malignancy and systemic amyloidosis should be initiated. Breast malignancy must also be excluded by performing in-depth radiologic-pathologic correlation to avoid unnecessary excisional biopsy. Amyloid should be included in the differential of all mammographic masses and calcifications.
Udayakumar N, Kasales C. JAOCR at the Viewbox: Amyloid Calcifications in Breast . J Am Osteopath Coll Radiol. 2021;10(1):41.
Dr. Kasales is with the Department of Diagnostic Imaging, Fox Chase Cancer Center, Philadelphia, PA