Hodgkin Lymphoma — Reed-Sternberg Cells

A 28-year-old woman presents with painless cervical lymphadenopathy and mediastinal mass on chest X-ray. Lymph node biopsy shows the structure marked **A** — large cells with abundant cytoplasm and two mirror-image nuclei, each containing a single prominent eosinophilic nucleolus surrounded by a clear halo. The neoplastic cells are surrounded by a rich inflammatory background of small lymphocytes and eosinophils. Which of the following immunophenotypic profiles is most consistent with the cells marked **A**?

A 28-year-old woman presents with painless cervical lymphadenopathy and B symptoms. Excisional lymph node biopsy is performed. Histology reveals a polymorphous inflammatory background with scattered large cells. The structure marked **A** in the diagram shows a large binucleated cell with prominent eosinophilic nucleoli giving an 'owl-eye' appearance. Immunohistochemistry shows this cell is CD15+, CD30+, and CD20−. Which of the following best describes the cell lineage and diagnostic significance of the structure marked **A**?