Paper II
Question
Classify Hodgkin Lymphoma. Describe the morphological features and immunohistochemical profile of Classical Hodgkin Lymphoma
Answer
Classification of Hodgkin lymphoma
Classical Hodgkin lymphoma (~95%)
- Nodular sclerosis (most common subtype)
- Mixed cellularity
- Lymphocyte-rich
- Lymphocyte-depleted
Nodular lymphocyte-predominant Hodgkin lymphoma (~5%) — a distinct, non-classical entity with different immunophenotype and clinical behaviour
Morphological features of Classical Hodgkin Lymphoma
- Diagnostic Reed-Sternberg cells — large binucleate or multinucleate cells with prominent eosinophilic (“owl’s eye”) nucleoli in each nuclear lobe, abundant cytoplasm
- Variants: mononuclear (Hodgkin) cells, lacunar cells (nodular sclerosis subtype — cells appear to sit in a clear space due to fixation artifact), and “mummified” cells (degenerate/apoptotic RS cells)
- The neoplastic RS cells are typically scattered as a minority population within a background of abundant reactive, non-neoplastic inflammatory cells — a mixture of small lymphocytes, eosinophils, plasma cells, and macrophages, giving the characteristic overall architecture
- Nodular sclerosis subtype: Broad bands of birefringent collagen fibrosis dividing the lymph node into nodules, with lacunar-type RS cells
- Mixed cellularity subtype: Diffuse effacement of nodal architecture by a heterogeneous inflammatory infiltrate with numerous classic RS cells, no significant fibrosis
Immunohistochemical profile of Classical Hodgkin Lymphoma
- Reed-Sternberg cells are typically positive for: CD15 and CD30
- Typically negative for: CD45 (leucocyte common antigen) and CD20 (B-cell marker, though may show weak/variable positivity in a minority)
- (Contrasts with nodular lymphocyte-predominant Hodgkin lymphoma, where the neoplastic “popcorn cells”/LP cells are CD20+, CD45+, but CD15- and CD30-)