Duloxetine in the management of chronic pruritus in plasma cell dyscrasias: 2 cases of monoclonal gammopathy of undetermined significance and multiple myeloma

Generalized pruritus without primary skin manifestations can be an early sign of serious systemic conditions, including plasma cell dyscrasias such as monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma. Although the pathophysiology of pruritus in these conditions remains incompletely understood, proposed mechanisms include inflammatory mediator release, neuropathic pathways, and paraprotein deposition in the skin. Effective management strategies are limited, and pruritus significantly impacts patients’ quality of life. Here, we describe 2 cases of generalized pruritus associated with plasma cell dyscrasias that improved with duloxetine therapy. Case 1 involves a 71-year-old male with IgG lambda MGUS and chronic refractory pruritus, who demonstrated significant improvement in symptoms with duloxetine 60 mg daily after failing multiple prior treatments, including biologicals and phototherapy. Case 2 details a 59-year-old female with recurrent IgA kappa multiple myeloma and a 10-year history of progressive pruritus, who similarly achieved substantial symptom control with duloxetine, supported by adjunctive therapies during disease recurrence. Both cases suggest that duloxetine, a serotonin-norepinephrine reuptake inhibitor with neuromodulatory and potential anti-inflammatory properties, may offer benefit in treating chronic pruritus in plasma cell dyscrasias, particularly when standard therapies fail. However, dose titration is critical to minimize adverse effects, notably sexual dysfunction observed at higher doses. Our findings support a multimodal approach to pruritus management, combining duloxetine with agents targeting neuropathic and inflammatory pathways. Further research is needed to better define duloxetine’s role, optimal dosing strategies, and patient selection criteria for treating pruritus in plasma cell dyscrasias. Early recognition and targeted management of pruritus in these patients may greatly improve quality of life and overall disease burden.