Monoclonal Gammopathy of Ocular Significance – A Case Report

Background

Plasma cell dyscrasias are a heterogeneous group of diseases, where clonal expansion of a plasma cell in the bone marrow leads to excessive production of an abnormal nonfunctional immunoglobulin or their parts [1]. In most cases, this monoclonal gammopathy is clinically asymptomatic, without malignancy criteria or the need for therapy. Based on the patientʼs symptoms, the burden of the monoclonal protein (also called M-protein or paraprotein), and the presence of organ damage, the disease may be classified into the following: monoclonal gammopathy of undetermined significance (MGUS), smoldering multiple myeloma (SMM), multiple myeloma (MM), Waldenström macroglobulinemia, chronic lymphocytic lymphoma, or other lymphoproliferative disorders [2]. MGUS is the most common plasma cell dyscrasia, affecting approximately 3% of the general population up to age 50, with an even higher prevalence in older individuals [3]. SMM is a premalignant disorder between MGUS and MM [2]. In contrast to MGUS, the degree of plasma cell infiltration in the bone marrow is higher (≥ 10%), which is usually reflected by a higher M-gradient in the serum [4]. Patients with MGUS and SMM are usually asymptomatic and do not display typical myeloma-associated end-organ damage such as anemia, hypercalcemia, lytic bone lesions, or renal failure [2]. Nevertheless, SMM carries a 10% per year risk of progression to symptomatic multiple myeloma over 5 years and a 65% cumulative risk 10 years after diagnosis [5].

Regardless of the diseaseʼs dignity and plasma clone size, all plasma cell dyscrasias can cause organ-related complications [6]. As early as 1934, Meesman first reported corneal stromal deposits in a patient with paraproteinemia, whereupon the term paraproteinemic keratopathy (PPK) was introduced [7]. However, because corneal involvement in systemic monoclonal gammopathies is rare and their clinical appearance may resemble other stromal pathologies, initial diagnosis remains challenging. We describe a case of SMM-associated keratopathy diagnosed in a university hospital in Switzerland.

Publication History

Received: 25 October 2023

Accepted: 13 November 2023

Article published online:
23 April 2024

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