Hodgkin Lymphoma - Reed-Sternberg Cells with Owl-Eye Binucleate Morphology

A 28-year-old woman presents with painless cervical lymphadenopathy and a mediastinal mass on chest X-ray. Excisional lymph node biopsy is performed. Histopathology reveals large cells (20–40 µm) with bilobed nuclei and prominent eosinophilic nucleoli occupying approximately 2% of the cellular infiltrate, surrounded by a polymorphous background of small lymphocytes, eosinophils, and plasma cells. Immunohistochemistry shows these large cells are CD15+, CD30+, and CD45 negative. The structure marked **A** in the diagram represents the diagnostic hallmark cells. Which of the following best describes the cellular origin and key immunophenotypic feature of these cells?