Background/Objectives: Serum protein electrophoresis (SPE) is a widely used laboratory test for the detection and monitoring of monoclonal gammopathies, including multiple myeloma (MM). Although SPE is usually recommended in the presence of specific clinical or laboratory abnormalities, monoclonal gammopathies may occasionally develop rapidly and without typical symptoms. This case report aims to emphasize the diagnostic value of SPE in identifying an unexpected and fast-evolving monoclonal gammopathy. Methods: We report the clinical and laboratory eight-month follow-up of a 58-year-old male who initially underwent SPE for unrelated clinical conditions. Serial SPE analyses were performed using capillary zone electrophoresis. When abnormalities emerged, immunotyping and serum free light chain (FLC) assays were conducted. The diagnostic workup was completed with bone marrow aspiration, flow cytometry, and imaging studies according to current international diagnostic criteria. Results: The initial SPE (November 2023) showed a normal protein profile. After eight months, follow-up SPE revealed a prominent monoclonal spike in the gamma region (2.9 g/dL), associated with increased total serum proteins (91 g/L; range 64–82 g/L), elevated IgA levels (20.0 g/L; range 0.4–3.5 g/L), and a markedly abnormal κ/λ FLC ratio (54.00; range 0.31–1.56). Bone marrow analysis demonstrated >18% plasma cell infiltration, confirming the diagnosis of IgA-κ MM. The patient underwent standard therapy followed by autologous stem cell transplantation, achieving disease remission. Conclusions: This case highlights that clinically relevant monoclonal gammopathies may arise rapidly in the absence of classical diagnostic features. Routine SPE represents a cost-effective and accessible screening tool that can identify subtle protein abnormalities, prompting the timely use of more specific and invasive diagnostic procedures for aggressive plasma cell disorders.
Iannelli et al. (2026) studied this question.