Search Results (85)

Objectives: Langerhans cell sarcoma (LCS) is a very rare, highly malignant tumor that originates from Langerhans cells. The differential diagnosis of LCS and Langerhans cell histiocytosis (LCH) still faces limitations, and the molecular changes involved in LCS are unclear. Molecular biomarkers and immunophenotypes may help distinguish between LCS and LCH. In this manuscript, the pathological and molecular markers in LCS are explored. Methods: The expression patterns of ASPP1, ASPP2, and inhibitor of apoptosis-stimulating p53 protein (iASPP) were examined using the immunohistochemical method and immunofluorescence staining. Then, genetic features, such as B-Raf proto-oncogene, serine/threonine kinase (BRAF) V600E, K-ras, and ROS proto-oncogene 1, receptor tyrosine kinase (ROS1), were assayed using the amplification refractory mutation system (ARMS) method. Finally, whole-exon sequencing of LCS was performed. Results: Immunohistochemically, in all samples of LCS, ASPP2 was detected in ovoid and elliptic tumor cells. In the case of LCH, ASPP2 was expressed not only in ovoid and elliptic cells but also in histiocytic cells. The expression of iASPP was observed in five cases LCS (5/6), and no positive reaction was observed in the case of LCH. No ASPP1 expression was observed in LCH and LCS. During triple-color immunofluorescence analysis, ASPP2 and iASPP were co-expressed on Langerin⁺ LCS tumor cells. No mutations of BRAF V600E, K-ras, or ROS1 were detected in LCH and LCS. No gene mutation or rearrangement was detected in LCS except for the MAP2K1 gene. The mutation site was nonsynonymous in 607 bp of MAP2K1, resulting in a change from base G to A; thus, the amino acid E changed to K at the 203 site (4/6, 66.67%). Conclusions: Combined detection of ASPP2 and iASPP in tissue samples may provide valuable markers to differentiate between LCH and LCS. The MAP2K1 variants c.607G > A is the first potential marker to be reported in LCS. Full article

Background/Objectives: Langerhans cell histiocytosis (LCH) is a rare myeloid neoplasm characterized by the clonal proliferation of Langerhans-like dendritic cells and constitutive activation of the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK-ERK) signaling pathway. Nearly 80% of ERK pathway activation can be attributed to B-Raf proto-oncogene, serine/threonine kinase (BRAF V600E), and mitogen-activated protein kinase kinase 1 (MAP2K1) variants, with BRAF V600E specifically detected in approximately 50% of pediatric LCH cases and associated with a higher risk of severe disease and treatment failure. The use of the HistioTrak clinical assay to detect the presence of BRAF V600E mutations in peripheral blood mononuclear cells (PBMCs) has emerged as a useful diagnostic tool and biomarker. Methods: This study is a single-center retrospective study that explores the favorable outcomes of treatment with trametinib on a small number of patients with LCH. We retrospectively analyzed the records of 11 children with LCH treated with trametinib at diagnosis as front-line therapy (n = 6), due to progressive disease (n = 3) or intolerance (n = 1) to chemotherapy, or at relapse (n = 1). Results: HistioTrak identified the presence of BRAF V600E PBMCs in five patients. In this small single-center retrospective cohort, trametinib was associated with favorable short-term outcomes in all patients, and serial HistioTrak testing appeared feasible in selected patients. Conclusions: Prospective studies are needed before routine diagnostic or monitoring use can be recommended. Full article

Background/Introduction: Standardized staging imaging for Langerhans Cell Histiocytosis (LCH) is lacking. This study aims to identify patient and disease factors that influence imaging selection and propose a clinical decision algorithm that supports more deliberate, radiation- and cost-conscious use of imaging. Methods: A retrospective review of patients with biopsy-proven LCH, evaluated at a single institution, was conducted from 2001 to 2025. Age, sex, and presenting location at diagnosis were compared across imaging groups (Positron emission tomography/computed tomography [PET/CT], bone scintigraphy, and skeletal survey). Disease extent (unifocal, multifocal, multisystem) was summarized according to the imaging modality each patient received. Results: The cohort included 78 patients: 30 PET/CT, 11 bone scans, and 37 skeletal surveys. Median age differed significantly by modality: PET/CT 34 years (interquartile range [IQR] 8–56) vs. bone scan 13 years (3–37) vs. skeletal survey 7 years (2–14) (p < 0.001). Imaging selection varied significantly by anatomic location (p = 0.016): bone lesions were assessed with skeletal survey (52.8%), PET/CT (28.3%), and bone scan (18.9%). All pulmonary cases received PET/CT imaging. Six of the 78 patients had multisystem disease, and all six had been staged with PET/CT (Fisher’s exact p = 0.006, PET/CT vs. skeletal survey; Bonferroni-adjusted p = 0.018). Conclusions: In addition to age, the initial presentation site influences the choice of imaging modality. Given the higher radiation burden and cost of PET/CT, further research is needed to determine whether this observed practice pattern translates to improved clinical outcomes. Full article

Multicentric reticulohistiocytosis (MRH) is a rare systemic histiocytic disorder of uncertain etiology characterized by papulonodular cutaneous lesions and potentially destructive polyarthritis, with variable multisystem involvement. Owing to its low prevalence, evidence for optimal management remains limited, and treatment responses are heterogeneous. Emerging reports suggest that Janus kinase (JAK) inhibition may provide benefit in refractory disease. We report a 60-year-old woman with MRH presenting with papulonodular skin lesions, symmetric polyarthritis, constitutional symptoms, and interstitial lung disease (nonspecific interstitial pneumonia pattern) in the context of co-existing primary biliary cholangitis and no evidence of malignancy. Prior therapies (glucocorticoids, methotrexate, leflunomide) achieved suboptimal control. Upadacitinib, a selective JAK1 inhibitor, induced rapid and complete remission of cutaneous and articular disease with improvement of pulmonary involvement. Secondary weight gain and incident diabetes were managed with tirzepatide. This case adds to the limited literature supporting JAK inhibition as a targeted option for refractory MRH, including multisystem disease with pulmonary involvement. Systematic evaluation of efficacy, durability, and safety is warranted. Full article

Background and Objective: Clavicular pain and swelling in children can have multiple causes and often require a multidisciplinary approach. We aimed to describe the characteristics and final diagnoses of children with clavicular involvement and to review the literature on this topic. Methods: We retrospectively reviewed patients younger than 18 years who were evaluated for clavicular symptoms at two pediatric rheumatology centers and one pediatric oncohematology center. These data were then descriptively compared with findings from 63 patients reported across 7 published articles. Results: Twelve patients (9 females, median age 10 years [IQR 9.4–10.5]) were included. Final diagnoses were chronic nonbacterial osteomyelitis (CNO; 8), Langerhans cell histiocytosis (LCH; 2), reactive arthritis (1), and Tietze syndrome (1). Clavicular involvement was mostly unilateral and localized to the medial clavicle in CNO. The most frequent presenting symptom was local swelling (11/12), followed by pain (9/12). Diagnostic delay was a median of 4 months (IQR 1–10.5). Whole-body MRI revealed multifocal lesions in 6/8 CNO patients. Biopsy was often required for diagnosis primarily to exclude malignancy and to clarify atypical or unifocal presentations. The literature review confirmed CNO as the most frequent cause, followed by rare tumors. Conclusions: CNO predominates among pediatric non-traumatic clavicular lesions, but LCH and rare conditions are not uncommon, underscoring the need for careful differential diagnosis and targeted imaging. Full article

Background and Clinical Significance: Cutaneous Rosai-Dorfman disease (CRDD) is a rare, benign histiocytic proliferative disorder, accounting for approximately 3% of all Rosai-Dorfman disease (RDD) cases. Currently, the diagnosis of CRDD relies on invasive pathological examination due to the absence of reliable non-invasive alternatives. This case series evaluates the potential utility of high-frequency ultrasound (HFUS) as an adjunctive diagnostic tool for CRDD. Case Presentation: We present three CRDD cases, correlating HFUS features with histopathology. All cases showed hypoechoic lesions with varying infiltration depths and morphologies, though no specific diagnostic features were identified. HFUS clearly delineated involvement of the dermal and subcutaneous layers, assessed morphological characteristics like contour regularity and border definition, and evaluated vascularity. This information is crucial for clinical decision-making. HFUS also demonstrated value in therapeutic follow-up. In Case 1, it objectively showed a reduction in lesion size and decreased internal vascularity, providing clear evidence of treatment response. Conclusions: Although HFUS cannot independently diagnose CRDD and histopathology remains the gold standard, it serves as a valuable complementary tool. HFUS allows evaluation of deeper tissue structures, infiltration depth, and vascularity. As a non-invasive modality, it is useful for treatment monitoring, therapy guidance, and prognosis assessment. Integrating HFUS into the CRDD workflow enables more comprehensive and precise management. Full article

Background and Clinical Significance: Histiocytosis encompasses Langerhans cell histiocytosis (LCH) and non-LCH, such as Erdheim–Chester disease (ECD). ECD or a mixed type of histiocytosis (LCH/ECD) may initially involve the central nervous system (CNS), resulting in a delayed diagnosis. More recently, dabrafenib and trametinib (Dab/Tra regimen) have become available in its treatment. Case Presentation: A 46-year-old woman with CNS involvement of mixed histiocytosis (BRAF V600E-positive LCH/ECD) was treated with combination therapy using a Dab/Tra regimen. At initial presentation, she exhibited central diabetes insipidus, dysarthria, and gait disturbance with mild spasticity and ataxia, requiring walking assistance even for short distances. The interval from the onset of central neurological symptoms to diagnosis of mixed histiocytosis was 4 years. The introduction of targeted therapy was 2 years later. After seven months of Dab/Tra therapy, partial neurological improvement was observed, as reflected by a decrease in the SARA score from 21/40 to 13/40 and the ICARS score from 33/100 to 28/100. However, further neurological recovery remained significantly delayed. Conclusions: We suspect that the limited improvement may be attributable to the delayed initiation of targeted therapy, in contrast to the more rapid and pronounced responses reported in cases where treatment was started earlier. Full article

Background and Clinical Significance: Histiocytic sarcoma (HS) is a rare and aggressive form of malignant histiocytosis, often associated with poor prognosis. The diagnosis and management of HS are challenging due to the complexity of its pathogenesis, molecular profile, and the unclear cellular origin of histiocytic neoplasms, compounded by the limited literature on treatment strategies. Case Presentation: We report the case of a young patient with HS localized to the lymph nodes, spleen, and liver, who also presented with hemophagocytic lymphohistiocytosis (HLH) documented on bone marrow biopsy. Initial treatment with CHOEP-21 and ICE-21 chemotherapy resulted in only a partial metabolic response, as evidenced by a Fluorodeoxyglucose-Positron Emission Tomography (FDG-PET)/CT scan. Given the aggressive nature of the disease and the presence of HLH, an allogeneic hematopoietic stem cell transplantation (HSCT) from a matched unrelated donor was performed as consolidation therapy, leading to a progressive complete response without significant toxicity. A suspected relapse at 18 months post-transplant was excluded following a mediastinal lymph node biopsy, which revealed a benign intravascular papillary endothelial hyperplasia (IPEH). Over five years post-diagnosis and more than four years after transplantation, the patient remains in complete remission with full functional recovery. Conclusions: This case highlights the diagnostic and molecular challenges of HS and demonstrates the curative potential of early allogeneic HSCT, even when only partial remission is initially achieved. Full article

Background: Recent advances in childhood cancer treatment and increased survival rates have led to a growing number of adolescents and young adults (AYAs) who are survivors of childhood cancer (CCSs). This study aimed to examine health status, health-related quality of life (HRQoL), and social outcomes in AYA CCSs. Methods: Sixty-two AYAs who were CCSs (treated within the same tertiary Pediatric Hematology–Oncology Department in Crete, Greece) were enrolled in the study. Self-reported HRQoL was assessed using the Short-Form Health Survey (SF-36). Sixty-five never-ill peers constituted the control group. Results: CCSs reach adolescence and young adulthood without significant deviations in HRQoL from their healthy peers. The presence and severity of late effects were significantly correlated with lower scores in physical health. The cancer type seems to play a pivotal role: Langerhans cell histiocytosis survivors displayed significantly lower scores in mental health, and brain tumor survivors scored substantially lower scores in physical functioning. Acute lymphoblastic leukemia survivors reported the highest scores in mental health. Age at diagnosis of neoplasia was negatively correlated with physical functioning. No significant sex differences were identified. Adherence to multiple healthy lifestyle behaviors (regular exercise, abstaining from alcohol consumption and smoking, and using sun protection) and active employment were correlated with significantly higher scores in mental health. Conclusions: Appropriate therapy and regular follow-up after treatment have led to improved clinical and social outcomes, as assessed by CCSs. More efforts are needed to increase awareness of avoiding harmful behaviors that raise the risk of late effects in this specific group. Full article

Histiocytic sarcoma (HS) is an ultra-rare hematopoietic neoplasm that frequently occurs in extranodal sites of adults. Clinically, HS demonstrates aggressive behavior and can arise de novo or in association with other hematological neoplasms. The median overall survival from the time of diagnosis is approximately six months. Histologically, HS is composed of sheets of large, round to oval cells with abundant eosinophilic cytoplasm and can be confused with a variety of benign and malignant conditions. Immunohistochemistry plays a crucial role in the diagnosis of HS, showing expression of CD163, CD68, lysozyme, and PU.1 and negative staining with follicular dendritic cell markers and myeloid cell markers. Recent studies have demonstrated a high rate of PD-L1 expression, suggesting a potential therapeutic target. Several genomic alterations have been identified in HS, including mutations involving the RAS/MAPK and PI3K/AKT/mTOR signaling pathways, CDKN2A mutations/deletions, and TP53 mutations. There is no standard protocol for the management of HS. Surgical resection with or without radiotherapy is the most common first-line treatment for unifocal/localized disease. The systemic treatment options for multifocal/disseminated disease are very limited. This review provides an overview of the current knowledge on the clinicoradiological features, histopathology, pathogenesis, and management of HS. Full article

Background/Objectives: The purpose of this study is to determine the added value of 18F-FDG PET/CT scan in pediatric LCH compared to other imaging modalities (CT and MRI) at initial staging, during assessment of disease reactivation, and after treatment. Methods: This is a retrospective study of children diagnosed with LCH between 1 June 2007 and 8 December 2022 who met the inclusion criteria. 18F-FDG PET CT imaging was compared to CT and/or MRI when available. The interclass correlation coefficient (ICC) was used to assess the agreement between methods. p-Values of less than 0.05 were considered statistically significant. Results: A total of 39 children had undergone 18F-FDG PET/CT studies. Median (range) age at presentation was 10 years (1.3–17 y), with a female-to-male ratio of 0.7:1. Excellent concordance (ICC = 1; p < 0.0001) between 18F-FDG PET/CT and other imaging methods was found. Median SUVmax of the positive FDG-avid lesions at initial staging was 2.7 [range 1.3–16.7]. Conclusions: 18F-FDG PET/CT has been shown to be complementary to diagnostic CT and MRI, with the advantage of demonstrating additional metabolic information at initial staging, during assessment of disease reactivation, and to assess interval changes post therapy. These preliminary findings warrant further investigation. Full article

Background: Langerhans Cell Histiocytosis (LCH) is a rare histiocytic hematological disorder that frequently involves the lungs. Due to a lack of data about sex-related differences in LCH, the aim of this study is to evaluate sex-related differences in pulmonary function in a cohort of patients with LCH. Methods: We retrospectively analyzed data from 79 adult patients diagnosed with LCH. Demographic, clinical, and spirometric data were collected and compared by sex. Continuous variables were analyzed using the Mann–Whitney test and categorical variables were analyzed with the Chi-square test. Results: Out of 79 patients, 47 (59.5%) were females and 32 (40.5%) were males. Women showed significantly lower diffusing capacity of the lungs for carbon monoxide (DLCO%) and lower diffusing capacity of the lungs for carbon monoxide per unit of alveolar volume (DLCO/VA%) compared to men. Females showed a trend toward lower small airway indices, including maximal expiratory flow at 25 (MEF₂₅%) and forced expiratory flow at 25–75% (FEF_25–75%), though this was not statistically significant, while the residual volume-to-total lung capacity (RV/TLC) ratio was significantly higher in women. Among the functional parameters, DLCO% showed the highest accuracy (AUC 0.70) in the identification of lung involvement after multivariate regression analysis. Conclusions: Our findings suggest that the combination of lower gas exchange efficiency and increased peripheral air trapping secondary to small airway involvement in female patients may reflect the presence of a distinct functional LCH phenotype in women characterized by early small airway involvement and altered ventilation–perfusion dynamics, which may influence the clinical management of these patients. Furthermore, the moderate predictive value of DLCO% for lung involvement at baseline in LCH women suggests that DLCO may contribute to the detection of LCH women with lung involvement, although it should not be considered a definitive diagnostic test without a prospective and independent external validation. Full article

Langerhans cell sarcoma (LCS) is a rare and aggressive neoplasm characterized by a clonal proliferation of Langerhans cells (LCs), with multi-organ involvement and poor prognosis. Diagnostic challenges arise from its rarity and overlapping features with Langerhans cell histiocytosis (LCH), requiring immunophenotypic and histological analysis for differentiation. This case report discusses a 67-year-old male with multi-organ LCS involvement. Diagnosis was confirmed via liver biopsy and genetic analysis, revealing a MAP2K1 mutation. Treatment with subcutaneous cladribine and dexamethasone resulted in significant clinical and radiological improvement, despite hematological toxicity due to an underlying myelodysplastic neoplasm (MDS). This case proves the potential efficacy of cladribine for disseminated LCS and highlights the necessity for further research into optimal therapeutic approaches for this rare malignancy. Full article

Over the past decade, the field of childhood histiocytosis, particularly Langerhans cell histiocytosis (LCH), has undergone transformative changes. The integration of molecular genetics, targeted therapies, and refined diagnostic methodologies has revolutionized patient management and redefined disease classification. This editorial provides a comprehensive overview of the pivotal developments from 2015 to 2025, highlights ongoing challenges, and explores future directions in research and clinical care. Full article

Introduction: The group of so-called “sellar-region masses” consists of a heterogeneous group of neoplasms and tumor-mimicking lesions, whose differential diagnosis may be challenging due to the overlapping of clinical and radiological features, which can be found both in “common” and “uncommon” lesions. The choice of a correct treatment strategy is still arduous and requires histological analysis. Gamma Knife Radiosurgery (GKRS) has already been reported as a safe and effective treatment in these cases. The objective of this study is to evaluate single-center pre-operative data, post-operative outcomes, and long-term follow-up in patients treated with GKRS for unusual sellar tumors. Methods: We retrospectively identified and analyzed nine patients treated with GKRS from 2004 to 2015, according to a standard protocol. Lesions consist of hypothalamic hamartoma (HH), Rathke’s cleft cist (RCC), Langerhans cell histiocytosis (LCH), spindle cell oncocytoma (SCO), choroid plexus papilloma (CPP), and ossifying fibroma (OF). The diagnosis was histologically confirmed in six patients that underwent surgery, while in three patients, diagnosis was based on characteristic clinical and radiological findings (two HH and one RCC). Pre-operative and post-operative data were retrieved from medical archives, and long-term follow-up was obtained through clinical and neuroradiological periodic examination. Results: In our series, all the “rare” sellar lesions treated, had a successful radiographic and clinical response in a medium-long follow-up period. Conclusions: The long-term follow-up results suggest that GKRS is a safe and effective treatment in rare sellar lesions, with very low toxicity. To the best of our knowledge, this report represents the largest series of unusual sellar lesions treated with GKRS in a single high-volume center, suggesting that GKRS might be an effective non-invasive adjuvant treatment option. Further studies and a larger number of patients are needed to confirm if residuals of these rare sellar lesions might regress on their own without treatment or if other non-invasive treatments could be as effective as GKRS. Full article