Pityriasis lichenoides (PL) is a papulosquamous disease that affects both adults and children. Previous studies have shown a subset of this entity to have clonal T-cell populations via PCR based assays. In this study, we sought to implement next generation sequencing as a more sensitive and specific test to examine for T-cell clonality within the pediatric population.We identified 18 biopsy specimens from 12 pediatric patients with clinical and histopathologic findings compatible with PL. Patient demographics, clinical features, management, and histopathologic findings were reviewed. All specimens were analyzed for clonality with next generation sequencing of T-cell receptor beta (TRB) and gamma (TRG) genes.Of the 12 patients, 9 (75%) had complete resolution of lesions at the time of data collection (mean follow up 31 months). The remaining three patients significantly improved with methotrexate (with or without acitretin). Interestingly, 7 of 12 patients (58%) and 9 of 17 biopsy specimens (53%) showed evidence of T-cell clonality. Two patients showed matching TRB clones from different anatomic sites.T-cell clonality is a common finding in PL, likely representing a "reactive clonality" rather than a true lymphoproliferative disorder. Clonality alone cannot be used as a means to distinguish PL from lymphomatoid papulosis or cutaneous lymphoma. This article is protected by copyright. All rights reserved.
View details for DOI 10.1111/cup.14143
View details for PubMedID 34614220