Localized AL Amyloidosis of the Breast: A Case Series.

Abstract 4906

AL amyloidosis is characterized by widespread, progressive deposition of fibrillar amyloid protein derived from monoclonal immunoglobulin light chains, leading to organ failure and death. This disease is typically systemic, however, it can occur as a localized form. In localized amyloidosis, the deposits occur near the site of synthesis of the precursor protein and in some cases, plasma cells have been demonstrated histologically adjacent to the deposits. For unknown reasons, the tracheobronchial tree is the most common site for localized AL amyloidosis. Localized AL amyloidosis of the breast is a rare entity that has been described in the literature in isolated case reports. It can present as a palpable mass or as calcifications on routine screening mammography. We report here a case series of seven women (median age 63 years, range 46 to75) seen and evaluated at Boston University Medical Center from 1990-2008. We evaluated 1502 new patients with AL amyloidosis in this time period, making the incidence of localized AL amyloidosis of the breast to be 0.5% at a single referral center. All seven patients had abnormal screening mammography with calcifications, and biopsies that revealed Congo red positive amyloid deposits. Histologically, the amyloid deposits appeared as amorphous material in the stroma around the ducts and lobules in most patients; one patient had amyloid deposits in the ducts only, but not in the stroma. None of the patients had clinical or laboratory evidence of other organ involvement, all had negative Congo red staining of an abdominal fat pad aspirate, and all had a negative work up for a plasma cell dyscrasia or circulating paraprotein. The patients were treated with local excision of the regions of calcification or lumpectomy. Three out of seven patients underwent routine follow up within 6-12 months from the time of diagnosis with no evidence of disease recurrence or progression to systemic AL amyloidosis. One out of seven patients had bilateral and recurrent amyloidosis of the breasts and was found to have an associated stage I invasive ductal adenocarcinoma that was treated with lumpectomy and radiation. In summary, breast amyloidosis is rare, is not associated with a systemic plasma cell dyscrasia or amyloidosis in other organs, and can be treated surgically.