Molecular Characterization of Vascular Transformation of Lymph Node Sinuses via Oncomine Comprehensive Assay.

Vascular transformation of lymph node sinuses (VTSs) is defined as phenotypic transformation of the lymph node sinusoidal lining from lymphatic to vascular endothelium. The pathogenesis of VTS remains unclear. Thus far, VTS has not been characterized at the molecular level. Herein, we shed some light on VTS pathogenesis while providing a detailed description of its clinical, histopathologic, immunophenotypic, and molecular features. Our specimens involved 2 women and 3 men, aged 36 to 66 years (mean 49 years old). The lymph nodes were in the right inguinal (n = 2), left axillary (n = 1), right renal perihilar (n = 1), and left external iliac (n = 1) regions. The lesions ranged from 0.5 cm to 1.5 cm (mean 0.9 cm). All 5 specimens showed no recurrences on follow-up. Three specimens exhibited a spindle cell subtype, 1 specimen showed a mixed subtype, and another specimen displayed solid subtype. Immunohistochemically, VTS demonstrated variable staining for CD31, CD34, ERG, D2-40, and SMA. Next-generation sequencing revealed mutations in ataxia-telangiectasia mutated (Tier I/II) and NBN (variants of uncertain significance [VUSs]) genes in 1 specimen, while mutations in POLE (VUS), FANCI (VUS), ARID1A (VUS), ERBB4 (VUS), and MSH6 (VUS) genes were seen in 3 other specimens. The VUS genomic alterations were regarded as germline mutations given their variant allele frequency approaching 50%. In conclusion, most genomic alterations in VTS are germline VUS with rare pathogenic Tier I/II mutation detected in 1 specimen. Based on our case series, it is appropriate to consider VTS as a nonneoplastic process until more data exist.