# Cutaneous Langerhans cell histiocytosis and other systemic inflammatory or autoimmune disease manifestations in the setting of clonal hematopoiesis

## TL;DR

An elderly woman with clonal hematopoiesis developed multiple inflammatory and autoimmune diseases, including cutaneous Langerhans cell histiocytosis and temporal arteritis.

## Contribution

This case suggests that clonal hematopoiesis may cause immune dysregulation leading to multi-organ autoimmune conditions.

## Key findings

- The patient had clonal hematopoiesis with somatic mutations in MAP2K1, IDH2, and SRSF2.
- High allele frequencies of IDH2 and SRSF2 mutations were found in peripheral blood.
- The findings suggest a possible future risk of myeloid malignancy.

## Abstract

The clinical manifestations and pathophysiology of clonal hematopoiesis (CH)‐associated immunological dysfunction are poorly understood. We describe an elderly woman with CH who developed various systemic inflammatory or autoimmune diseases (SIADs), including cutaneous Langerhans cell histiocytosis (LCH) and temporal arteritis. Sequencing of the LCH revealed somatic oncogenic mutations in MAP2K1, IDH2, and SRSF2, with enrichment of the latter two in her peripheral blood at high allele frequencies. These findings raise concern for the future development of a myeloid malignancy. Given the mounting evidence for adult‐onset autoinflammatory conditions caused by somatic blood mutations, we suspect CH‐mediated immune dysregulation is contributing to her multi‐organ involvement by a combination of SIADs.