Thrombocytopenia Preceding CRAB Development and Tracking Disease Activity in Multiple Myeloma: A Four-Patient Case Series
The 2014 IMWG revised diagnostic criteria expanded multiple myeloma (MM) diagnosis beyond CRAB features to include myeloma-defining biomarkers, enabling earlier recognition before irreversible end-organ damage. Despite these advances, thrombocytopenia with paraproteinemia and elevated beta-2 microglobulin (β2M) remains underrecognized, often misattributed to immune thrombocytopenia (ITP), resulting in diagnostic delay. We describe four patients in whom thrombocytopenia preceded CRAB development by several months and whose platelet counts tracked disease activity throughout their clinical course, suggesting a potential role for thrombocytopenia as both an early clinical manifestation and a dynamic marker of disease behavior in MM.
Materials and Methods/Case Presentation/Objective: We retrospectively reviewed a single-center cohort of 35 patients diagnosed with MM over one year and identified four female patients (ages 52-78 years; mean 65.25 years) presenting with thrombocytopenia as their only initial clinical abnormality, concurrent with monoclonal protein detection and elevated β2M, in the absence of CRAB criteria. All had been previously diagnosed and managed as ITP before definitive hematologic evaluation. We analyzed the diagnostic interval, CRAB development during that interval, ISS stage at diagnosis, treatment response, and platelet count evolution in relation to disease activity.
Results/Description/Main Outcome Measure(s):
Platelet counts at presentation ranged from 55 to 81 ×10⁹/L. Monoclonal subtypes included IgG (n=2), IgA (n=1), and non-secretory kappa MM (n=1). Bone marrow plasma cell infiltration ranged from 13% to 60%.
In all four patients, the triad preceded CRAB development by 3 to 12 months. During this interval, three patients developed lytic bone lesions, two developed renal impairment, and one developed anemia. At definitive diagnosis, three patients (75%) had reached ISS stage III, associated with median overall survival of 29 months and 5-year survival of 47%, versus 62 months and 77% for ISS stage I.
Three patients received myeloma-directed therapy with VRD, CyBorD, or thalidomide-based regimens; two achieved complete response, while one demonstrated treatment intolerance and refractory disease. Platelet count evolution mirrored disease behavior: one patient achieved normalization from 55 to 215 ×10⁹/L with concurrent myeloma response, while another maintained stable counts alongside marked IgA reduction. In contrast, the refractory patient demonstrated persistent thrombocytopenia (34 ×10⁹/L) across multiple treatment lines and ongoing paraprotein burden. One patient remains under surveillance without treatment.
Conclusion(s).: In this series, thrombocytopenia was the earliest identifiable manifestation of MM, consistently preceding CRAB development by several months. Platelet count improvement occurred concurrently with disease response, while persistent thrombocytopenia accompanied refractory disease, suggesting platelet counts may reflect disease activity in selected patients. These findings highlight a persistent gap between established diagnostic criteria and real-world recognition, as all four patients were managed as ITP despite concurrent paraproteinemia. Unexplained thrombocytopenia with paraproteinemia and elevated β2M should prompt evaluation for plasma cell dyscrasia - including serum protein electrophoresis, free light chains, bone marrow examination, and appropriate imaging - even without classical CRAB features. Prospective studies are warranted to determine whether thrombocytopenia carries independent predictive value beyond established MM risk stratification models.
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