Classical Hodgkin lymphoma (CHL)
| S/no. | Diagnostic points and pitfalls |
|---|---|
| 1. | CHL has many morphological mimics. The defining feature is an appropriate background non-neoplastic inflammatory cell infiltrate where the HRS cells reside. Even if the large B cells are morphologically and immunohistochemically similar to HRS cells, an intimately admixed background of non-Hodgkin's lymphoma (eg, T-cell lymphoma) is inconsistent with CHL. |
| 2. | MUM1 is a highly sensitive (but not specific) stain for HRS cells and can be useful in accurately localising them, assisting comparison of the results of other immunostains. |
| 3. | LR-CHL can mimic NLPHL morphologically and express B cell markers more frequently than other subtypes of CHL. Demonstration of strong expression of CD30 with or without CD15 and/or EBER-ISH positivity, as well as CD45/LCA negativity helps to distinguish LR-CHL from NLPHL. |
EBER-ISH, Epstein-Barr virus by in situ hybridisation for EBER; HRS, Hodgkin/Reed-Sternberg; LCA, leucocyte common antigen; LR-CHL, lymphocyte-rich classical Hodgkin lymphoma; NLPHL, nodular lymphocyte-predominant Hodgkin lymphoma