Peripheral T-Cell Lymphoma Classifications and CD30 Testing

Transcript:

Neha Mehta-Shah, MD: Peripheral T-cell lymphomas are a relatively uncommon subset of non-Hodgkin lymphomas. They make up about 10% of all non-Hodgkin lymphomas. There are about 7000 cases per year. About half of those are the systemic peripheral T-cell lymphomas. And the most common types of those are peripheral T-cell lymphoma not otherwise specified, angioimmunoblastic T-cell lymphoma, and anaplastic large cell lymphoma that then gets subdivided into ALK positive and ALK negative. The anaplastic large cell lymphomas are identified by both their histological appearance, and they always express the protein CD30 on the cell surface.

CD30 is a protein expressed on the cell surface of certain cells. It’s also expressed on the malignant cells of Hodgkin lymphoma, and it’s expressed on a subset of T-cell lymphomas. Anaplastic large cell lymphoma always expresses the protein CD30, but about a third or a fifth of cases of peripheral T-cell lymphoma NOS not otherwise specified and angioimmunoblastic T-cell lymphoma also express CD30. And the way we check for that is by immunohistochemistry. Sometimes by flow cytometry you can also check for a CD30, but most conventionally it’s been done by immunohistochemistry.

Yes, so there’s a number. Although we talked about the most common entities of peripheral T-cell lymphoma, there are 23 or so types of T-cell lymphomas, and there are a number of more rare subtypes as well, including breast implant—associated anaplastic large cell lymphoma. This was recently incorporated into the WHO [World Health Organization] as an entity. The other change recently in the WHO classification was a separation of an entity called enteropathy-associated T-cell lymphoma into 2 different groups: enteropathy-associated T-cell lymphoma and mucosa enteropathy intestinal T-cell lymphoma, which are now 2 separate categories. These were previously called ETL type 1 and type 2, so those were also recently reclassified.

Also in the recent classification, there is a distinction of a particular subset of peripheral T-cell lymphoma not otherwise specified, called the T follicular helper phenotype of this disease. And this has elements also seen in the disease, angioimmunoblastic T-cell lymphoma. The reason why this is becoming important is we’re learning that different subtypes of T-cell lymphoma might be more sensitive to certain types of therapy, and we’re exploring new therapies that are probably more subtype specific than was previously done.

Transcript Edited for Clarity