Uncommon Mimics the Rare: Lipid Versus Paraproteinemic Keratopathy in a Patient With Smoldering Multiple Myeloma

A 69-year-old man with smoldering IgA lambda multiple myeloma developed progressive bilateral peripheral corneal opacities initially concerning for paraproteinemic keratopathy (PK). Despite recommendations for systemic therapy, histopathologic analysis of corneal tissue obtained during penetrating keratoplasty (PKP) demonstrated lipid-laden stromal deposits without immunoglobulin staining, confirming lipid keratopathy (LK). This case illustrates the diagnostic challenge of distinguishing LK from PK in patients with monoclonal gammopathies and emphasizes the need for histopathologic confirmation before initiating systemic therapy. Accurate differentiation can prevent unnecessary treatment and guide appropriate management of corneal deposition disorders associated with plasma cell dyscrasias.