To determine whether Langerhans' histiocytosis is a polyclonal reactive disease or a clonal disorder, we used X-linked polymorphic DNA probes (HUMARA, PGK, M27 beta[DXS255], and HPRT) to assess clonality in lesional tissues and control leukocytes from 10 female patients with various forms of the disease.
Although PPT2 deficiency has not been described in humans, manifestations would be predicted to include neurodegeneration with bone marrow histiocytosis, visceromegaly, brown pancreas, and linkage to chromosome 6p21.3 in affected families.
Of interest, SEMA6A protein was strongly expressed on skin and bone LCs and on LCs in draining lymph nodes from patients with LC histiocytosis or dermatopathic lymphadenitis, respectively, representing two inflammatory conditions in which LCs display an immature DC-LAMP(low), CD83(low), and CCR7+ phenotype.
Recent findings of biallelic mutations in SLC29A3 in 2 families reported to have familial RDD and in a kindred with Faisalabad histiocytosis (OMIM 602782), which is an autosomal inherited form of histiocytosis with similarities to RDD, may explain the RDD-like immunophenotype in our H syndrome case.
With the exception of insulin-dependent diabetes and mild finger and toe contractures in one sibling, the two patients with nasal granulomatous histiocytosis studied here displayed none of the many SLC29A3-associated phenotypes.
These studies suggest a cellular and molecular basis for the development of histiocytosis in several human syndromes associated with ENT3 mutations and potentially other LSDs.
Molecular, immunophenotypic, and sequencing analyses seem to define it as a histiocytic-mesenchymal transition and intermediate proliferative histiocytosisnot associated with mtDNA large deletion and pathogenic mutation, as well as the SLC29A3 gene mutation.
We conclude that male patients with chronic idiopathic uveitis should be questioned about a history of hemophagocytic lymphocytic histiocytosis during their workup and screened for BIRC4 mutation if appropriate.
We reviewed 73 biopsies from 42 patients showing involvement by histiocytosis from a variety of organ systems, including bone (16), retroperitoneum (11), skin (19), orbit (6), brain (5), lung (6), cardiac structures (2), epidural soft tissue (3), oral cavity (2), subcutaneous soft tissue (2), and testis (2).
Future studies with long-term follow-up are required to determine if pediatric BRAFV600E positive CNS-JXG neoplasms are a distinct entity in the L-group histiocytosis category or represent an expanded pediatric spectrum of ECD.
In this study, we uncovered activating mutations in CSF1R and rearrangements in RET and ALK that conferred dramatic responses to selective inhibition of RET (selpercatinib) and crizotinib, respectively, in patients with histiocytosis.
The clinicopathological spectrum of ALK-positive histiocytosis is broader than originally described, and this entity is characterized by frequent presence of KIF5B-ALK gene fusion.
Our 2 cases highlight previously unrecognized diversity of ALK-positive histiocytosis in clinical manifestation, organ involvement, and cytomorphologic features and further elucidate the diagnostic challenges of this rare entity.
Herein, we report a 23-year-old woman with severe pancytopenia diagnosed with non-LCH following presentation with pancytopenia and marrow examination showing histiocytosis positive for CD45, CD68, CD136, and lysozyme but negative for CD1a, langerin, and S100.
Langerhans cell histiocytosis (LCH) is the most common histiocytosis with constitutive activation of the RAS-RAF-MEK-ERK (MAPKinase) cell signaling pathway.
Langerhans cell histiocytosis (LCH) is the most common histiocytosis with constitutive activation of the RAS-RAF-MEK-ERK (MAPKinase) cell signaling pathway.
In vivo, mice lacking myeloid FLCN reveal chronic macrophage activation, leading to profound histiocytic infiltration and tissue disruption, with hallmarks of human histiocytic syndromes like Erdheim-Chester Disease.