Prevalence of corneal findings and their interrelation with hematological findings in monoclonal gammopathy

Abstract

Purpose: To determine prevalence of paraproteinemic keratopathy (PPK) among patients with monoclonal gammopathy (MG). To evaluate interrelation between corneal and hematological parameters in patients with PPK.

Methods: Fifty-one patients with monoclonal gammopathy of undetermined significance (n = 19), smoldering multiple myeloma (n = 5) or multiple myeloma (n = 27) were prospectively included in this study. Best-corrected visual acuity, slit-lamp biomicroscopy, Scheimpflug tomography, in-vivo confocal laser scanning microscopy, optical coherence tomography and complete hematological workup were assessed.

Results: We identified n = 19 patients with bilateral corneal opacities compatible with PPK. PPK was newly diagnosed in 13 (29%) of 45 patients with a primary hematological diagnosis and in n = 6 patients without previous hematological diagnosis. The most common form was a discreet stromal flake-like PPK (n = 14 of 19). The median level of M-protein (p = 0.59), IgA (p = 0.53), IgG (p = 0.79) and IgM (p = 0.59) did not differ significantly between the patients with and without PPK. The median level of the FLC κ in serum of patients with kappa-restricted plasma cell dyscrasia was 209 mg/l in patients with PPK compared to 38.1 mg/l in patients without PPK (p = 0.18). Median level of FLC lambda in serum of patients with lambda-restricted plasma cell dyscrasia was lower in patients with PPK compared to patients without PPK (p = 0.02).

Conclusion: The PPK was mostly discreet, but its prevalence (29%) was higher than expected. Median level of the monoclonal paraprotein was not significantly higher in patients with PPK compared to patients without PPK. Our results suggest a lack of correlation between morphology and severity of the ocular findings and severity of the monoclonal gammopathy.

Trial registration: German Clinical Trial Register: DRKS00023893.

Fig 1

Stromal flake paraproteinemic keratopathy (PPK) in diffuse (a) and slit-shaped (b) light beam; c peripheral superficial band-like PPK; d lattice-like PPK in direct retro illumination (yellow arrows point the lattice lines); e stromal punctiform crystalline-like deposits; f central golden-brown discoloration of the pre-Descemet layer.

Fig 2. In vivo confocal laser scanning microscopy: Extracellular hyperreflective needle-like deposits at the level of 284 μm in patient with stromal flake-like PPK associated with multiply myeloma of type IgG kappa.

Red arrows point keratocytes; yellow arrows point needle-like paraprotein deposits.

Fig 3. Presentation of the different types of paraproteinemic keratopathy (PPK) with their case number and serological type.

X-axis: morphologic types of PPK; Y-axis: number of patients representing each type of PPK and the respective monoclonal paraprotein. Κ–kappa, λ–lambda, Ig–Immunoglobulin, LC–light-chain.