# TET2 germline mutation in a patient with sequential lymphoid malignancies: a novel case report

## TL;DR

A 30-year-old man with a TET2 gene mutation developed three different lymphoid cancers in sequence, highlighting the gene's role in cancer progression.

## Contribution

First documented case of sequential lymphoid malignancies linked to a germline TET2 mutation.

## Key findings

- The patient developed MCCHL, AITL, and T-ALL in sequence due to a TET2 germline mutation.
- Sequencing confirmed the TET2 mutation was germline, not acquired during cancer development.
- The case highlights TET2's role in lymphoid cancer development and progression.

## Abstract

We report a case of a 30-year-old male patient with a germline heterozygous TET2 R1354fs mutation, who successively developed three distinct lymphoid malignancies: mixed cellularity classical Hodgkin lymphoma (MCCHL), angioimmunoblastic T-cell lymphoma (AITL), and T-cell acute lymphoblastic leukemia (T-ALL). Sequencing analysis of the oral mucosa and bone marrow specimens during the remission phase confirmed the germline origin of the TET2 mutation. This represents the first documented case of the sequential transformation across three distinct lymphoid malignancies attributable to a germline TET2 mutation, underscoring its pivotal role in lymphomagenesis and clonal evolution.

The online version contains supplementary material available at 10.1007/s00277-026-06930-4.