Among patients with Erdheim-Chester disease (ECD), it is important to evaluate adults with histiocytosis for a concomitant myeloid neoplasm, researchers concluded after conducting a multi-institutional cohort analysis involving 189 individuals.

Investigators looked at patients who had ECD and ECD overlapping with Langerhans cell histiocytosis. Among the results:

• 10% of patients with ECD had an overlapping myeloid neoplasm, typically a myeloproliferative neoplasm (MPN), myelodysplastic syndrome (MDS), or mixed MDS/MPN overlap syndrome.
• Molecular analysis often spotted hallmark driver mutations of myeloid neoplasms coexisting with those characteristic of histiocytosis.
• Patients with histiocytosis with a concomitant myeloid malignancy tended to be substantially older.
• They also were more likely to present with mixed histiocytosis than those without a myeloid malignancy.
• Discrete kinase mutations in the histiocytosis and myeloid neoplasm led to discordant and adverse responses to kinase-directed targeted therapies in selected cases.