biostudies-literatureEmile JFNCI NIH HHS157-170https://www.ebi.ac.uk/biostudies/studies/S-EPMC9364113biostudies-literatureUnknown398(10295)Histiocytoses constitute a heterogeneous group of rare disorders, characterised by infiltration of almost any organ by myeloid cells with diverse macrophage or dendritic cell phenotypes. Histiocytoses can start at any age. Diagnosis is based on histology in combination with appropriate clinical and radiological findings. The low incidence and broad spectrum of clinical manifestations often leads to diagnostic delay, especially for adults. In most cases, biopsy specimens infiltrated by histiocytes have somatic mutations in genes activating the MAP kinase cell-signalling pathway. These mutations might also be present in blood cells and haematopoietic progenitors of patients with multisystem disease. A comprehensive range of investigations and molecular typing are essential to accurately predLancet (London, England)Histiocytosis.PMC9364113P30 CA008748Haroche JIdbaih ARollins BJEmile JFCohen-Aubart FDonadieu JFraitag SCollin MAbdel-Wahab OfalseHistiocytosis.Histiocytoses constitute a heterogeneous group of rare disorders, characterised by infiltration of almost any organ by myeloid cells with diverse macrophage or dendritic cell phenotypes. Histiocytoses can start at any age. Diagnosis is based on histology in combination with appropriate clinical and radiological findings. The low incidence and broad spectrum of clinical manifestations often leads to diagnostic delay, especially for adults. In most cases, biopsy specimens infiltrated by histiocytes have somatic mutations in genes activating the MAP kinase cell-signalling pathway. These mutations might also be present in blood cells and haematopoietic progenitors of patients with multisystem disease. A comprehensive range of investigations and molecular typing are essential to accurately pred2021-01-01T00:00:00Z2021 Jul2025-04-26T16:19:04.467Z2025-04-06T15:06:41.582ZS-EPMC93641133390141910.1016/S0140-6736(21)00311-110.1016/s0140-6736(21)00311-1