A 26‑year‑old woman presents with a painless lump in her neck that she first noticed 6 weeks ago. She reports drenching night sweats, unintentional weight loss of 6 kg over 2 months, and intermittent low‑grade fevers. On examination, there are multiple enlarged, rubbery, non‑tender cervical lymph nodes. There is also mild splenomegaly. Her full blood count shows: Hb 108 g/L WCC 8.2 × 10⁹/L Platelets 230 × 10⁹/L ESR 78 mm/h A chest X‑ray shows a widened mediastinum. An excisional lymph node biopsy has already been performed.