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7 slides generated from the cancer page, with a quiz from the open benchmark and speaker notes that cite the sources. Arrow keys move between slides; Print gives one slide per page.
A lymphoma of the chest that sits between two diseases: it has some of the features of primary mediastinal B-cell lymphoma and some of classic Hodgkin lymphoma, and a pathologist cannot put it cleanly in either. It is recognised as an entity of its own, and the 2022 classifications restricted the name to lymphomas that involve the mediastinum.
What it is. The mediastinum is the space in the middle of the chest between the lungs, and it contains the thymus. Two lymphomas grow there in young adults: primary mediastinal large B-cell lymphoma and nodular sclerosis classic Hodgkin lymphoma. They are biologically related, and some tumours fall between them, with the cell size and sheet-like growth of one and the surface markers of the other. WHO-HAEM5 describes it as a single biological group with a spectrum running from classic Hodgkin lymphoma to primary mediastinal B-cell lymphoma, with mediastinal grey zone lymphoma straddling the two.
How it differs from its neighbours. The distinguishing feature is the mismatch between what the cells look like and what they express. Classic Hodgkin lymphoma has rare large cells in a sea of immune cells and has lost most of its B-cell programme; grey zone lymphoma keeps a high density of tumour cells and keeps the B-cell markers. The International Consensus Classification writes that requirement down: a diagnosis needs both a high density of tumour cells and strong expression of at least two B-cell markers. A tumour that looks like nodular sclerosis Hodgkin lymphoma and happens to express CD20 variably is still Hodgkin lymphoma.
| Setting | Approach | Guideline |
|---|---|---|
| Making the diagnosis, and the trap in it | The diagnosis needs a generous biopsy, because the appearance varies across a single tumour and a core needle may sample only the part that looks like one of the neighbouring diseases. Both 2022 classifications require involvement of the mediastinum: an identical-looking tumour elsewhere in the body is diffuse large B-cell lymphoma, not otherwise specified. A nodular sclerosis classic Hodgkin lymphoma with variable CD20 expression remains Hodgkin lymphoma and is not reclassified here. | not mapped |
| Treatment | Treated with regimens designed for aggressive large B-cell lymphoma and containing rituximab, rather than with Hodgkin lymphoma chemotherapy, because the tumour retains its B-cell programme and the surface target with it. Radiotherapy to the residual mediastinal mass is used in some series. There is no randomised trial in this entity, the published series number in the tens, and the regimen is chosen in a multidisciplinary meeting; the detail sits on the primary mediastinal B-cell lymphoma page and in the treatment layer of this family. | not mapped |