Original ArticlesMasson Trichrome and Sulfated Alcian Blue Stains Distinguish Light Chain Deposition Disease From Amyloidosis in the LungKunnath-Velayudhan, Shajo MBBS, MMST*; Larsen, Brandon T. MD, PhD†; Coley, Shana M. MD, PhD*; De Michele, Simona MD*; Santoriello, Dominick MD*; Colby, Thomas V. MD†; Bhagat, Govind MD*; Saqi, Anjali MD, MBA*Author Information *Department of Pathology and Cell Biology, Columbia University Irving Medical Center and New York-Presbyterian Hospital, New York, NY †Department of Pathology, Mayo Clinic, Scottsdale, AZ G.B. and A.S. contributed equally. Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article. Correspondence: Anjali Saqi, MD, MBA, Department of Pathology and Cell Biology, New York-Presbyterian Hospital-Columbia University Irving Medical Center, Columbia University, 622 West 168th Street, New York, NY 10032 (e-mail: [email protected]). The American Journal of Surgical Pathology: March 2021 - Volume 45 - Issue 3 - p 405-413 doi: 10.1097/PAS.0000000000001593 Buy Metrics Abstract Light chain deposition disease, characterized by nonamyloidogenic deposits of immunoglobulin light chains, is rare in the lung and possibly underdiagnosed due to low clinical suspicion and lack of readily accessible tests. We encountered a case of pulmonary light chain deposition disease (PLCDD) in which light chain deposits appeared crimson red with a Masson trichrome (MT) stain and salmon pink with a sulfated Alcian blue (SAB) stain. This prompted us to characterize a series of PLCDD cases and assess the utility of MT and SAB stains to distinguish them from amyloidosis. From the pathology archives of 2 institutions spanning 10 years, we identified 11 cases of PLCDD, including 7 diagnosed as such and 4 determined retrospectively. The deposits in all cases of PLCDD stained crimson red with MT and salmon pink with SAB, while the cases of pulmonary amyloid (n=10) stained blue-gray and blue-green, respectively. The immunoglobulin light chain nature of the deposits was confirmed in 10 of 11 cases by either immunofluorescence microscopy (n=5) or mass spectrometry (n=5). Transmission electron microscopy revealed osmiophilic, electron-dense deposits in all cases analyzed (n=3). An extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue type was diagnosed in 10 cases and 1 represented a plasma cell neoplasm. Our study highlights the importance of considering PLCDD in the differential diagnosis of amyloid-like deposits in the lung and the value of performing MT and SAB stains to distinguish between PLCDD and amyloidosis. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.