Clinicopathologic and Proteomic Analysis of Amyloidomas Involving the Ocular Surface and Adnexa.

<bold>Objectives: </bold>Ocular amyloidoma is a rare disorder characterized by deposition of insoluble proteinaceous fibrils in the extracellular space of the ocular adnexa. This study details the clinicopathologic features and proteomic characteristics of periocular amyloid deposition.<bold>Methods: </bold>Specimens (1991-2020) were retrieved and reviewed. All available H&E slides and special stains were reviewed. Proteomic analysis was performed using immunohistochemistry (IHC) for IgG, IgG4, IgA, IgD, IgM, CD20, CD3, CD138, and κ/λ, as well as chromatography-electrospray tandem mass spectrometry on formalin-fixed, paraffin-embedded tissue.<bold>Results: </bold>There were 14 patients (7 men, 7 women). The depositions involved eyelid (n = 3), conjunctiva (n = 8), and orbit (n = 3). All patients were adults with a median age at diagnosis of 56 (range, 39-88) years. The deposits were predominantly λ light chain restricted (n = 6) and mixed light chains (n = 2), and one case was κ predominant. Two of the cases with a mixture of κ and λ light chains had an excess of transthyretin by mass spectrometry. Four of the cases did not have adequate material for proteomic subtyping.<bold>Conclusions: </bold>Amyloidomas involving ocular adnexa contain a variety of amyloid-related and immunoglobulin-associated peptides. The λ light chain predominates as in other body sites, but mixed patterns and rarely κ light chain restriction may be encountered. [ABSTRACT FROM AUTHOR]