Extranodal NK/T-cell lymphoma, nasal type

"Extranodal" means it starts outside the lymph nodes. In this lymphoma that is most often the nose, the sinuses or the roof of the mouth, which is where "nasal type" comes from.

It arises from natural killer cells or from T cells — both are immune cells, and natural killer cells are a part of the immune system that attacks infected or abnormal cells directly rather than through antibodies.

It is rare. Lymphoma Action puts UK diagnoses at around 20 a year, typically in people in their fifties and sixties, more often men.

Epstein-Barr virus is found inside the lymphoma cells in essentially every case, detected by a specific laboratory test on the biopsy.

It is more common in Asian and South American populations, with increasing reports from Western countries. The sources do not explain why, and it is not accurate to call it an Asian disease.

The cause is not established. Epstein-Barr virus is present in the lymphoma cells in essentially all cases, but the sources do not describe it as a sufficient cause — and the reason is arithmetic. Carrying that virus is close to universal among adults, and this lymphoma is vanishingly rare.

None of the sources we read describes an inherited cause, a lifestyle cause or an environmental exposure.

Because it starts in the nose, sinuses or palate, early symptoms can look like a sinus problem, and that can delay recognition. That is a pattern rather than something we have a measured figure for.

It grows quickly.

Because it often starts in one place, a substantial share of people have disease that is still localised when it is found, and early-stage disease is treated as a distinct category from advanced disease.

The NCI groups it with the peripheral T-cell lymphoma subtypes that carry worse survival.

The usual lymphoma chemotherapy regimens do not work here, and for once there is a clean explanation. Natural killer cells carry high levels of a pump on their surface that expels drugs back out of the cell. That makes them resistant to several of the drugs those regimens rely on.

So treatment uses a different class of drug, based on asparaginase, which is not affected by that pump. Several combinations built around it are in use.

For early-stage disease, radiotherapy to the affected area is combined with chemotherapy, so people are managing both at the same time. Radiotherapy dose matters — lower doses resulted in more relapses.

The transplant picture here is genuinely unsettled, and that is covered in the next section rather than glossed over.

It can begin as something that looks and feels like a persistent sinus problem, which means some people have been investigated or treated for something else first.

Early-stage treatment means radiotherapy to the face and chemotherapy at the same time. Radiotherapy to that area brings its own effects on the mouth, taste and swallowing.

It is rare enough that most people will need referral to a specialist centre, and rare enough that there is little written for patients rather than for clinicians.

None of the sources we read reports on quality of life, diagnostic delay or long-term follow-up for this condition, so we have not written about those.

This is one of the conditions where a donor transplant is genuinely part of the conversation. It is also one where the published expert sources do not agree with each other, and we are going to say so rather than quote the one that suits us.

EBMT’s 2025 recommendations state in their narrative text that a donor transplant is strongly recommended as part of first-line therapy for this disease, along with two other rare T-cell lymphomas. They add that people transplanted in remission do better, but that those whose disease is stable or progressing should still be considered, because other treatments do not usually produce long-term remission.

A 2022 expert review of how these lymphomas are treated takes a different position: that a transplant using the person’s own cells is generally not recommended first-line, and that a donor transplant offers a potential cure through the donor’s immune system attacking the lymphoma but is not routinely recommended, because too many people die of the transplant itself.

Both are acceptable sources. Two groups of specialists have read the same evidence and reached different conclusions, and that is the actual state of knowledge here rather than a gap in our reading.

What is not in dispute: if a transplant does happen, the version that offers the possibility of long-term remission is the one using a donor’s cells, because it works through the donor’s immune system. And where no relative matches, that donor comes from a registry.