Question
Hodgkin’s lymphoma
Answer
Hodgkin lymphoma is a lymphoid neoplasm characterized by the presence of the diagnostic Reed-Sternberg (RS) cell in a background of reactive, non-neoplastic inflammatory cells.
Reed-Sternberg cell: A large cell with abundant cytoplasm and either a single nucleus with two nuclear lobes (or two separate nuclei), each with a large, eosinophilic, “inclusion-like” nucleolus — giving the classic “owl-eye” appearance. RS cells are of B-cell origin (derived from germinal centre B cells) and are typically positive for CD15 and CD30, but negative for CD45 and (usually) CD20.
WHO Classification:
- Classical Hodgkin lymphoma (~95%), subtypes:
- Nodular sclerosis — most common subtype overall; characterized by broad bands of birefringent collagen dividing the lymph node into nodules, and “lacunar cells” (RS variant with retracted cytoplasm in formalin-fixed tissue); common in young adults, often with mediastinal involvement.
- Mixed cellularity — numerous classic RS cells in a mixed inflammatory background (lymphocytes, eosinophils, plasma cells, histiocytes); associated with EBV; often presents at a more advanced stage.
- Lymphocyte-rich — abundant reactive lymphocytes with fewer RS cells; good prognosis.
- Lymphocyte-depleted — rare, sparse reactive lymphocytes with numerous RS cells/sarcomatous variants; associated with HIV; poor prognosis.
- Nodular lymphocyte-predominant Hodgkin lymphoma (~5%) — characterized by “popcorn cells” (L&H cells, a RS variant) that are CD20+/CD45+ but CD15/CD30 negative; distinct clinical behaviour (indolent, tends to relapse, low risk of transformation to diffuse large B-cell lymphoma).
Clinical features: Painless lymphadenopathy (often cervical/mediastinal), may show contiguous spread to adjacent lymph node groups (unlike non-Hodgkin lymphoma), B symptoms (fever, night sweats, weight loss) in more advanced disease, staged by the Ann Arbor system. Generally has a good prognosis with modern chemo/radiotherapy.