Elevated lymphoma risk in patients with chronic pruritus and chronic prurigo

BACKGROUND AND OBJECTIVES: Chronic pruritus (CP) and chronic prurigo (CPG, including prurigo nodularis) are prevalent, debilitating diseases with diverse comorbidities, including malignancies. This retrospective cohort study evaluated the prevalence and risk of lymphoma in CP and CPG patients, including key risk factors, and sex- and ancestry-related disparities. PATIENTS AND METHODS: We utilized electronic health records from the TriNetX US Collaborative Network (2011-2024), including 1,032,281 CP and 124,611 CPG patients (without prior lymphoma), matched to non-CP/non-CPG controls. Lymphoma risk was evaluated up to 5 years post-diagnosis. Sensitivity, sex- and ancestry-stratified analyses were performed. Multivariate analyses identified risk factors. RESULTS: Lymphoma developed in 0.29 % of CP (controls: 0.10 %, HR 2.90, 95 % 95 % CI: 2.71-3.12) and 0.30 % of CPG patients (controls: 0.10 %, HR 2.85, 95 % CI: 2.33-3.48; both p < 0.0001). The HR for cutaneous lymphoma was 6.62 (95 % CI 5.02-8.72) for CP and 10.95 (95 % CI 4.39-27.35) for CPG (p < 0.0001 each). Findings remained robust across all sensitivity analyses. Significant lymphoma risk factors included elevated serum lactate dehydrogenase, beta 2-microglobulin, male sex, immunosuppressant use, and White ancestry. CONCLUSIONS: CP and CPG patients have an increased lymphoma risk, linked to specific biomarkers, highlighting the importance of increased clinical vigilance in their management.