Photo Credit: Md Saiful Islam Khan

The following is a summary of “Clinical characteristics, molecular aberrations, treatments, and outcomes of malignant histiocytosis,” published in the February 2024 issue of Hematology by Ruan et al. 

Malignant histiocytosis (MH) is an exceptionally uncommon neoplasm arising from the macrophage-dendritic cell lineage.

Researchers started a retrospective study to analyze and present the clinical profiles, genetic abnormalities, therapeutic interventions, and patient outcomes of individuals diagnosed with MH across two referral centers (January 2000 to May 2023).

They identified 43 MH patients, comprising 26 with histiocytic sarcoma (MH-H), 9 with interdigitating dendritic cell sarcoma (MH-IDC), and 8 with Langerhans cell sarcoma (MH-LC). The median age at diagnosis was 61 years (range, 3–83), with 33 patients (77%) presenting with multifocal disease and 10 exhibiting unifocal involvement.

The results showed that tumor specimens from 22 patients (51%) underwent targeted next-generation sequencing, with 19/22 (86%) exhibiting at least one pathogenic mutation, including mutations in MAPK pathway genes (73%). The median OS for the entire cohort was 16 months (95% CI: 8–50). Those with multifocal disease had notably shorter outcomes than their unifocal counterparts, with a median OS of 10 months versus 50 months (P=.07). Patients with risk organ involvement (bone marrow, spleen, or liver) experienced significantly inferior outcomes. Chemotherapy and surgery emerged as the most common first-line treatments for multifocal and unifocal disease, respectively. Despite the overall poor outcome for patients with multifocal disease, a subset of patients demonstrated durable responses to treatment.

Investigators concluded that MH exhibits diverse clinical presentations, frequent cancer-causing mutations, and a prognosis heavily influenced by the spread and affected organs.

Source: onlinelibrary.wiley.com/doi/full/10.1002/ajh.27263