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Background Methods Results Conclusions Crystal‐storing histiocytosis (CSH) is a rare form of histiocytosis with intralysosomal accumulations of immunoglobulins or paraproteins that aggregate as crystals. Central nervous system (CNS) involvement of CSH is uncommon but should be considered in cases of persistent parenchymal enhancement on neuroimaging.We describe one local case of CNS CSH and 10 additional cases identified by literature review.Among 11 CSH patients, lesions involved either the dura (2/11) or brain parenchyma (9/11). Two cases had leptomeningeal enhancement. One case had spinal cord involvement. Two cases were associated with marginal zone lymphoma; one case was associated with an immunoglobulin A‐plasma cell dyscrasia. Eight of 11 cases had outcome data available: 7/8 cases had clinical and/or radiological improvement and 1/8 had radiological stability.Central nervous system involvement of CSH is rare. Potential cases should be comprehensively evaluated for lymphoma or myeloma with positron emission tomography/computed tomography (CT) of the body or alternatively, CT of the chest, abdomen, pelvis and nuclear bone scan, bone marrow biopsy, serum protein electrophoresis, and cerebrospinal fluid protein electrophoresis. Treatment is targeted toward the underlying malignancy. [ABSTRACT FROM AUTHOR]

Erdheim Chester Disease (ECD) is a rare histiocytic neoplasm with heterogeneous features. It can frequently be misdiagnosed if proper clinical and radiological details are not available. Biopsy with confirmatory immunohistochemistry (IHC) for BRAFV600E or molecular analysis for the gene forms the mainstay of diagnosis. Most ECD patients require treatment and the choice of therapy must be individualized based on clinical characteristics. Herein is reported one such case of ECD in a 45-year-old male who remains disease-free after six months of follow-up. [ABSTRACT FROM AUTHOR]

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Background: Histiocytic neoplasms are defined by too many histiocytes accumulating in various tissues, including the skin, bones, lymph nodes, and central nervous system. They are uncommon blood-related disorders that constitute <1% of cancers found in soft tissues and lymph nodes. Most referred to as Langerhans cell histiocytosis (LCH) or non-LCH, there are over 100 different sub-types that are divided into five groups. Here, a 76-year-old male presented with an intramedullary thoracic LCH., Case Description: A 76-year-old male presented with the month of slowly progressive bilateral lower extremity weakness (i.e., right > left) accompanied by decreased left-sided sensation below the T7 level. The enhanced thoracic magnetic resonance (MR) imaging documented an intradural intramedullary nodule at the T5 level with a syrinx extending from C7 to T10. The patient underwent a T4-T6 laminectomy for complete resection of the lesion. CD163 and CD68 studies highlighted a small, spindled-shaped tumor with occasionally enlarged histiocytes without co-positivity for S100. Pathologically, the lesion was considered an isolated intramedullary thoracic LCH., Conclusion: A 76-year-old male presented with progressive paraparesis of 1 month's duration attributed to an enhanced MR-documented T5 single intramedullary T5 thoracic LCH that was successfully resected., Competing Interests: There are no conflicts of interest., (Copyright: © 2024 Surgical Neurology International.)

Histiocytic cell tumors present as a difficult group of diseases in terms of differential diagnosis due to their rare frequency, heterogeneous clinical manifestations and ambiguous clinical course. Considering MAPK-signaling pathway mutations role (including BRAFV600E) in the pathogenesis of histiocytic cell tumors the importance of genetic studies in the diagnosis and choice of therapeutic strategy in these diseases increases. In the current issue modern classifications of histiocytic cell tumors, morphological and immunophenotypic features of histiocytic and dendritic cells, and the role of recurrent somatic mutations of the MAPK signaling pathway in the pathological histiocytic proliferation are presented. Particular attention is given to Langerhans cell histiocytosis, Erdheim–Chester disease and juvenile xanthogranuloma. Clinical and diagnostic characteristics of these diseases and therapeutic approaches are presented.

Juvenile Xanthogranuloma (XG) is a rare disorder that belongs to the heterogeneous group of histiocytic neoplasms, characterized by a clonal expansion of non-Langerhans cell histiocytes that share a dermal macrophage phenotype. Although the head and neck region is the most common reported site of involvement by the Juvenile Xanthogranuloma family, laryngeal localization is extremely rare. We report a unique case of Adult Onset Xanthogranuloma with subglottic localization, presenting as a solitary laryngeal mass without other systemic or cutaneous lesions. A review of the previously described cases of laryngeal Xanthogranuloma has been performed, highlighting 7 cases of Juvenile Xanthogranuloma and only 3 cases of Adult Onset Xanthogranuloma. Despite the extreme rarity of laryngeal localization of XG, this histiocytic neoplasm should be considered as a differential diagnosis for laryngeal masses causing airway obstruction, even in the absence of other concomitant manifestations. [ABSTRACT FROM AUTHOR]

Canine histiocytic sarcoma (HS) is an aggressive and highly metastatic neoplasm. Mutations in src homology 2 domain‐containing phosphatase 2 (SHP2; encoded by PTPN11), which recently have been identified in canine HS tumour cells, could be attractive therapeutic targets for SHP099, an allosteric inhibitor of SHP2. Here, molecular characteristics of wild‐type SHP2 and four SHP2 mutants (p.Ala72Gly, p.Glu76Gln, p.Glu76Ala and p.Gly503Val), including one that was newly identified in the present study, were investigated. Furthermore, in vivo effects of SHP099 on a HS cell line carrying SHP2 p.Glu76Ala were examined using a xenograft mouse model. While SHP2 Glu76 mutant cell lines and SHP2 wild‐type/Gly503 mutant cell lines are highly susceptible and non‐susceptible to SHP099, respectively, a cell line carrying the newly identified SHP2 p.Ala72Gly mutation exhibited moderate susceptibility to SHP099. Among recombinant wild‐type protein and four mutant SHP2 proteins, three mutants (SHP2 p.Ala72Gly, p.Glu76Gln, p.Glu76Ala) were constitutively activated, while no activity was detected in wild‐type SHP2 and SHP2 p.Gly503Val. Activities of these constitutively activated proteins were suppressed by SHP099; in particular, Glu76 mutants were highly sensitive. In the xenograft mouse model, SHP099 showed anti‐tumour activity against a SHP2 p.Glu76Ala mutant cell line. Thus, there was heterogeneity in molecular characteristics among SHP2 mutants. SHP2 p.Glu76Ala and perhaps p.Glu76Gln, but not wild‐type SHP2 or SHP2 p.Gly503Val, were considered to be oncogenic drivers targetable with SHP099 in canine HS. Further studies will be needed to elucidate the potential of SHP2 p.Ala72Gly as a therapeutic target of SHP099 in canine HS. [ABSTRACT FROM AUTHOR]

Purpose of Review: This report provides an overview of the current knowledge of molecular characterization, clinical description, and treatment of Erdheim-Chester disease (ECD), a multi-systemic adult histiocytosis of the L group. Recent Findings: The recent identification of several MAPK mutations in histiocytes of ECD lesions. Leading to targeted therapies. Summary: The discovery of the BRAFV600E mutation in ECD lesions followed by several other kinase mutations in the MAPK pathway has revolutionized our understanding of the disease pathogenesis and led to trials with targeted therapies that demonstrated robust efficacy. [ABSTRACT FROM AUTHOR]

Background: Xanthoma disseminatum (XD) is a rare benign histiocytic proliferating disease of non-Langerhans cell origin, which is clinically mainly characterized by cutaneous or mucous lesions. Although XD is acknowledged of one systematic disease, involvement of the central nervous system is quite rare. Case presentation: We presented one 34-year-old Chinese female with disseminated intracranial XD without cutaneous or oral mucosal papules and masses of the other organs. MR imaging displayed multiple heterogeneous masses with intense enhancement in the right frontal lobe, temporal lobe, corpus callosum, left cuneus, suprasellar region, and right cerebellum. Pathological examination showed a neoplastic lesion composed of plentiful epitheloid or spindle cells. The cell had pink cytoplasm of vacuolation and foam with deviated nucleus absent of atypia and mitosis. The histiocytic markers including CD163, CD11c, Mac387 and CD68 were positive, whereas S-100, CD1a, GFAP, CD21, CD23 and so on were negative immunohistochemically. Conclusions: Intracranial XD without systemic involvement was extremely rare, which was supposed to be considered in differential diagnosis with other neoplasms of histiocytic origin or gliomas. [ABSTRACT FROM AUTHOR]

Background Neoplasms of histiocytic and dendritic cell origin, including follicular dendritic cell sarcoma (FDCS), histiocytic sarcoma (HS) and interdigitating dendritic cell sarcoma (IDCS), are extremely rare, and data on their natural history and treatment outcomes are sparse. We evaluated the impact of surgery, radiation and systemic therapies on overall survival (OS). Methods We conducted a retrospective chart review of patients with FDCS, IDCS and HS treated at Memorial Sloan Kettering Cancer Center between 1995 and 2014. Results We identified 31, 15 and 7 patients with FDCS, HS and IDCS, respectively. Median age was 48.7, 42.3 and 58.8 years for FDCS, HS and IDCS, respectively. Only a slight disparity in gender distribution existed for FDCS and HS; however, IDCS predominantly affected males (6:1). The most common sites of presentation were abdomen and pelvis (42%), extremities (33%) and head and neck (57%) for FDCS, HS and IDCS, respectively. At diagnosis, 74%, 40% and 86% of patients presented with localised disease in FDCS, HS and IDCS, respectively. Patients with localised disease had significantly improved OS than those with metastatic disease in FDCS ( P = 0.04) and IDCS ( P = 0.014) but not in HS ( P = 0.95). In FDCS and HS, adjuvant or neo-adjuvant therapy was not associated with improved OS compared with observation. In IDCS, surgery alone provided a 5-year overall survival rate of 71%. Conclusions Adjuvant or neo-adjuvant treatment in FDCS and HS did not affect OS. Patients with IDCS had an excellent outcome with surgery. In the metastatic setting, chemotherapy and small molecule inhibitors may provide benefit. [ABSTRACT FROM AUTHOR]

The article reviews the changes in the structure of classification, diagnostic criteria for myeloid and histiocytic neoplasms in the 5 th edition of the WHO Classification of Tumors of Hematopoietic and Lymphoid Tissues (2022). Information is presented regarding new nosological forms, renaming and abolition of some previously existing ones. The importance of molecular genetic studies in the isolation of myeloid and histiocytic neoplasms and the need to apply these studies in clinical practice are emphasized. Myeloid and histiocytic precancerous and proliferative processes, genetic tumor syndromes, introduced into the classification for the first time, are considered.

Introduction: Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis (LCH) of unknown origin that was first described in 1930. Since then, almost 600 cases have been reported worldwide. Even though this disease primarily affects the bone, it has a varied clinical spectrum of presentation ranging from asymptomatic bone lesions to multisystem involvement. Owing to its protean manifestations ECD is often misdiagnosed or diagnosed late., Case Report: We present a 48-year-old female with a long long-standing history of recurrent bone lesion of the tibia and multiple trivial trauma fractures of long bones. Recently, she also developed a persistent headache and painful swelling of the right shoulder and left hip joint. Radiographs revealed multiple lytic and lytic sclerotic lesions. With the probable diagnosis of LCH, she underwent biopsy which revealed features characteristic of ECD., Conclusion: This case highlights the fact that histopathological confirmation is the key to distinguish various types of histiocytic neoplasms. Overlapping clinical and radiological features with atypical manifestations can occur in both LCH and ECD and does not rule out either of them., Competing Interests: Conflict of Interest: Nil, (Copyright: © Indian Orthopaedic Research Group.)

Characterizes ossifying fibromyxoid tumor of soft parts (OFMT). Landmark research reports on OFMT; Criteria for malignancy and classification; Histopathological characteristics of OFMT; Line of differentiation; Differences among typical, atypical and malignant OFMT; Immunohistochemical features of OFMT.