Breast amyloidosis: A systematic review.

e19572 Background: Breast amyloidosis is a rare occurrence often initially mistaken as malignancy on screening mammogram. It has only been reported in case reports and case series previously. This is an important disease to diagnose given its strong association with systemic amyloidosis and concurrent hematologic malignancy. The purpose of this systematic review is to provide an overview of the cases of breast amyloidosis and to assess for novel correlations within this patient population. Methods: This systematic review followed the PRISMA framework. Case reports and case series were identified through PubMed, Science Direct, DOAJ, and JSTOR using the keywords, “breast amyloid OR breast amyloidosis.” The review was conducted from inception to September 2024. Cases that were not written in English and did not have Congo Red staining performed were excluded from the analysis. Results: A total of 1,137 articles were screened with 106 being included in the study. A total of 190 unique patients with a median age of diagnosis at 62.7 years were included. This review found unexpectedly that 17.3% ( n = 33) of patients had an associated autoimmune disease. Specifically, 8.4% of the patients ( n = 16) had concomitant Sjögren’s syndrome which had previously not been identified in the literature. To characterize the breast amyloidosis patient population, 4.9% were Asian ( n = 2), 24.4% were Black ( n = 10), 68.3% were Caucasian ( n = 28), and 2.4% were Hispanic ( n = 1). The majority of biopsies were prompted by a breast mass seen on mammography (54%) with the next highest cause for biopsy being calcifications seen on mammography (31%). AL kappa was identified as the type of amyloid in 36% of cases ( n = 40), and AL lambda was identified 30.6% of cases ( n = 34). In addition, an associated hematologic malignancy was identified in 36.5% of patients ( n = 65), and 27.3% of patients had associated systemic amyloidosis ( n = 45). Both rates lower than the suggested near 50% for each in previous case series. Conclusions: This is the first systematic review to characterize breast amyloidosis. There is a novel finding that breast amyloidosis is correlated with autoimmune diseases and specifically Sjögren’s syndrome, and more research is needed to understand this pathophysiologic mechanism potentially related to the underlying inflammation of the autoimmune conditions. The characterization of these patients provides a deeper understanding of this disease process with both associated hematologic malignancy and systemic amyloidosis being less frequent than previously thought.