Long-term outcome and prognosis of mixed histiocytosis (Erdheim-Chester disease and Langerhans Cell Histiocytosis).

Background: Erdheim-Chester disease (ECD) is a rare histiocytosis that may overlap with Langerhans Cell Histiocytosis (LCH). This "mixed" entity is poorly characterized. We here investigated the clinical phenotype, outcome, and prognostic factors of a large cohort of patients with mixed ECD-LCH. Methods: This retrospective study was performed at two referral centers in France and Italy (Pitié-Salpêtrière Hospital, Paris; Meyer Children's Hospital, Florence). We included children and adults with ECD diagnosed in 2000-2022 who had biopsy-proven LCH, available data on clinical presentation, treatment and outcome, and a minimum follow-up of one year. Outcomes included differences in clinical presentation and survival between mixed ECD-LCH and isolated ECD; we also investigated response to treatments and predictors of survival in the mixed cohort. Survival was analyzed using the Kaplan-Maier method and differences in survival with the long-rank test. Cox regression models were used to evaluate the potential impact of age and gender on survival and to identify predictors of non-response and survival. Findings: Out of a cohort of 502 ECD patients, 69 (14%) had mixed ECD-LCH. Compared to isolated ECD, mixed ECD-LCH occurred more frequently in females (51 vs. 26%, p < 0.001) and in patients with multisystem disease (≥4 sites). Mixed ECD-LCH more frequently involved long bones (91 vs. 79%, p = 0.014), central nervous system (51 vs. 34%, p = 0.007), facial/orbit (52 vs. 38%, p = 0.031), lungs (43 vs. 28%, p = 0.009), hypothalamic/pituitary axis (51 vs. 26%, p < 0.001), skin (61 vs. 29%, p < 0.001), and lymph nodes (15 vs. 7%, p = 0.028); the BRAFV600E mutation was also more frequent in mixed ECD-LCH (81 vs. 59%, p < 0.001). Targeted treatments (BRAF and/or MEK inhibitors) induced response more frequently than conventional therapies (interferon-α, chemotherapy), either as first-line (77 vs. 29%, p < 0.001) or as any line (75 vs. 24%, p < 0.001). After a median follow-up of 71 months, 24 patients (35%) died. Survival probability was comparable between ECD alone and mixed ECD-LCH (log-rank p = 0.948). At multivariable analysis, age at diagnosis (HR 1.052, 95% CI 1.008-1.096), associated hematologic conditions (HR 3.030, 95% CI 1.040-8.827), and treatment failure (HR 9.736, 95% CI 2.919-32.481) were associated with an increased risk of death, while lytic bone lesions with a lower risk (HR 0.116, 95% CI 0.031-0.432). Interpretation: Mixed ECD-LCH is a multisystem disease driven by the BRAFV600E mutation and targeted treatments are effective. Age at diagnosis, bone lesion patterns, associated hematologic conditions, and treatment failure are the main predictors of death in mixed ECD-LCH. Funding: None.

Clinical phenotype of adult-onset systemic histiocytosis harboring BRAF in-frame deletions.

Not available.

Impact of BRAFV600E mutation on aggressiveness and outcomes in adult clonal histiocytosis.

Histiocytoses encompass a wide spectrum of diseases, all characterized by tissue infiltration by CD68+ histiocytes. Most adult histiocytoses are considered clonal diseases because they highlight recurrent somatic mutations in the MAP-kinase pathway gene, primarily BRAF. The presence of BRAF mutation is associated with widespread disease in children with Langerhans cell histiocytosis (LCH) or cardiovascular/neurological involvement in Erdheim-Chester disease (ECD). Nevertheless, few data are available on adult clonal histiocytosis. This is why we have conducted a retrospective study of all patients with clonal histiocytosis in our institution and present the data according to the presence of BRAF mutation. Among 27 adult patients (10 ECD, 10 LCH, 5 Rosai-Dorfman disease (RDD), and 3 mixed ECD/LCH), 11 (39%) have BRAF mutation with gain of function (n = 9) and deletion (n = 2). Those patients had frequent multicentric disease with risk organ involvement, especially the brain and cardiovascular system. They had frequent associated myeloid neoplasms (mostly chronic myelomonocytic leukemia) and received more frequently targeted therapy as the front-line therapy. Nevertheless, its presence did not affect the overall survival or relapse-free survival probably due to the emergence of efficient therapies. To conclude, rapid and accurate molecular establishment in adult clonal histiocytoses is crucial because BRAFV600E mutation correlates with multicentric disease with organ involvement and incomplete metabolic response.

Increased neopterin in cerebrospinal fluid in active adult neurohistiocytosis.

Diagnosis of neuro-histiocytosis is challenging and relies on clinical presentation, imaging, and cerebrospinal fluid (CSF) analysis to exclude differential diagnoses. Brain biopsy remains the gold standard for accurate diagnosis, but it is rarely performed because of the risk of the procedure and the low rentability in neurodegenerative presentation. Therefore, there is an unmet need to identify a specific biomarker for diagnosing neurohistiocytosis in adults. Because microglia (brain macrophages) is involved in the pathogenesis of neurohistiocytosis and produces neopterin secondary to aggression, the purpose of our study was to evaluate the value of the CSF neopterin levels for the diagnosis of active neurohistiocytosis. Of the 21 adult patients with histiocytosis, four patients had clinical symptoms compatible with neurohistiocytosis. In the two patients with a confirmed diagnosis of neurohistiocytosis, CSF neopterin levels were elevated as well as IL-6 and IL-10 levels. In contrast, the two other patients in whom the diagnosis of neurohistiocytosis was infirmed and all other patients with histiocytosis without active neurological disease involvement had normal CSF neopterin levels. In summary, increased CSF neopterin concentration represented a valuable tool for diagnosing active neuro-histiocytosis in adults with histiocytic neoplasms in this preliminary study.

Dramatic Efficacy of Interferon and Vemurafenib on Psychiatric Symptoms Revealing BRAFV600E -Mutated Erdheim-Chester Disease: A Case Report.

Erdheim-Chester disease (ECD) is a rare condition with underestimated neurological involvement. Mild psychiatric symptoms such as mood swings have been rarely described in the clinical spectrum of neuro-ECD. We here describe the first patient with psychiatric manifestations of delirium revealing ECD with neurological involvement with favorable evolution under interferon followed by BRAF inhibitor monotherapy. An 81-year-old woman was referred to the hospital because of delirium and severe cognitive impairment associated with a cerebellar syndrome. Brain magnetic resonance imaging showed "FLAIR-changes" lesions in the pons and upper cerebellum peduncles. Blood and cerebrospinal fluid (CSF) analyses showed normal results except for an elevated neopterin level in the CSF. Whole-body CT scan (18FDG-PET) showed peri-nephric fat infiltration and aorta adventitia sheathing with radiotracer uptake in the pons, vessels, peri-nephric fat, and bone lesions, which was characteristic of ECD. The diagnosis was confirmed on perirenal tissue biopsy, which also showed a BRAFV600E mutation. Treatment with interferon resulted in the resolution of delirium, and treatment with BRAF inhibitor subsequently resulted in a partial remission of all active sites. This case highlights that delirium can be the first manifestation of neurodegenerative ECD. ECD should be screened in unexplained psychiatric features as interferon and targeted therapy appear to be effective in this situation.

Case Report: Evolution of a Severe Vascular Refractory Form of ECD Requiring Liver Transplantation Correlated With the Change in the Monocyte Subset Analysis.

Erdheim-Chester disease is a rare histiocytosis characterized by iconic features associated with compatible histology. Most patients have somatic mutations in the MAP-kinase pathway gene, and the mutations occur in CD14+ monocytes. Differentiation of the myeloid lineage plays a central role in the pathogenesis of histiocytosis. Monocytes are myeloid-derived white blood cells, divided into three subsets, but only the CD14++CD16- "classical monocyte" can differentiate into dendritic cells and tissue macrophages. Since most mutations occur in CD14+ cells and since ECD patients have a particular monocytic phenotype resembling CMML, we studied the correlation between disease activity and monocytic subset distribution during the course of a severe vascular form of ECD requiring liver transplantation. During early follow-up, increased CD14++CD16- "classical monocyte" associated with decreased CD14lowCD16++ "non-classical monocyte" correlated with disease activity. Further studies are needed to confirm the use of monocyte as a marker of disease activity in patients with ECD.

USAID Associated with Myeloid Neoplasm and VEXAS Syndrome: Two Differential Diagnoses of Suspected Adult Onset Still's Disease in Elderly Patients.

BACKGROUND: Patients with solid cancers and hematopoietic malignancy can experience systemic symptoms compatible with adult-onset Still's disease (AOSD). The newly described VEXAS, associated with somatic UBA1 mutations, exhibits an overlap of clinical and/or biological pictures with auto inflammatory signs and myelodysplastic syndrome (MDS). OBJECTIVES: To describe a cohort of patients with signs of undifferentiated systemic autoinflammatory disorder (USAID) concordant with AOSD and MDS/chronic myelomonocytic leukemia (CMML) and the prevalence of VEXAS proposed management and outcome. METHODS: A French multicenter retrospective study from the MINHEMON study group also used for other published works with the support of multidisciplinary and complementary networks of physicians and a control group of 104 MDS/CMML. RESULTS: Twenty-six patients were included with a median age at first signs of USAID of 70.5 years with male predominance (4:1). Five patients met the criteria for confirmed AOSD. The most frequent subtypes were MDS with a blast excess (31%) and MDS with multilineage dysplasia (18%). Seven patients presented with acute myeloid leukemia and twelve died during a median follow-up of 2.5 years. Six out of 18 tested patients displayed a somatic UBA1 mutation concordant with VEXAS, including one woman. High-dose corticosteroids led to a response in 13/16 cases and targeted biological therapy alone or in association in 10/12 patients (anakinra, tocilizumab, and infliximab). Azacytidine resulted in complete or partial response in systemic symptoms for 10/12 (83%) patients including 3 VEXAS. CONCLUSIONS: Systemic form of VEXAS syndrome can mimic AOSD. The suspicion of USAID or AOSD in older males with atypia should prompt an evaluation of underlying MDS and assessment of somatic UBA1 mutation.

Immune Thrombocytopenia Revealing Enriched IgG-4 Peri-Renal Rosai-Dorfman Disease Successfully Treated with Rituximab: A Case Report and Literature Review.

Immune thrombocytopenia (ITP) is a rare autoimmune-mediated condition characterized by isolated thrombocytopenia (<100 G/L) after exclusion of other causes. Mostly primary, it is associated with hematological malignancy, autoimmune disorders, or infection in 20% of patients. It is exceptionally described in patients with histiocytosis, mostly in children (seven patients in literature). We report a case of a 69-year-old man with ITP leading to the diagnosis of histiocytosis. At ITP's diagnosis, the patient had elevated gamma-globulins leading to computed tomography showing bilateral peri-renal infiltration. The biopsy showed enriched IgG-4 peri-renal Rosai Dorfman disease with MAP2K1 mutation, although peri-renal infiltration is highly suggestive of Erdheim-Chester disease. This overlapping association was described in men with mutation in MAP2K1 gene. Macrophages are implicated in the pathophysiology of ITP in multiple ways, notably by the phagocytosis of opsonized platelets and their function of antigen-presenting cells able to stimulate autoreactive T cells. Histiocytic cells derivate from monocyte-macrophage lineage. Activation of macrophages in active histiocytosis is responsible for consequential platelet destruction in ITP associated histiocytosis. Finally, this case highlights a rare presentation of ITP revealing histiocytosis, both being efficiently treated with rituximab.

Peritoneal or mesenteric tumours revealing histiocytosis.

OBJECTIVE: Peritoneal or mesenteric tumours may correspond to several tumour types or tumour-like conditions, some of them being represented by histiocytosis. This rare condition often poses diagnostic difficulties that can lead to important time delay in targeted therapies. Our aim was to describe main features of histiocytoses with mesenteric localisation that can improve the diagnostic process. DESIGN: We performed a retrospective study on 22 patients, whose peritoneal/mesenteric biopsies were infiltrated by histiocytes. RESULTS: Abdominal pain was the revealing symptom in 10 cases, and 19 patients underwent surgical biopsies. The diagnosis of histiocytosis was proposed by initial pathologists in 41% of patients. The other initial diagnoses were inflammation (n=7), sclerosing mesenteritis (n=4) and liposarcoma (n=1). The CD163/CD68+CD1a- histiocytes infiltrated subserosa and/or deeper adipose tissues in 16 and 14 cases, respectively. A BRAFV600E mutation was detected within the biopsies in 11 cases, and two others were MAP2K1 mutated. The final diagnosis was histiocytosis in 18 patients, 15 of whom had Erdheim-Chester disease. The median diagnostic delay of histiocytosis was 9 months. Patients treated with BRAF or MEK inhibitors showed a partial response or a stable disease. One patient died soon after surgery, and five died by the progression of the disease. CONCLUSION: Diagnosis of masses arising in the mesentery should be carefully explored as one of the possibilities in histiocytosis. This diagnosis is frequently missed on mesenteric biopsies. Molecular biology for detecting the mutations in BRAF or in genes of the MAP kinase pathway is a critical diagnostic tool.

Characteristics of Adult Patients with Idiopathic Retroperitoneal Fibrosis and Assessment of Risk of Relapse at Diagnosis.

OBJECTIVES: To compare adult patients' characteristics suffering from idiopathic retroperitoneal fibrosis between "relapse-free" and relapsing patients at the diagnosis and identify factors associated with relapse at initial presentation. METHODS: We conducted a retrospective multicentric study in four hospitals in Eastern France, from 1993 to 2020, of adult patients suffering from idiopathic retroperitoneal fibrosis. We analyzed clinical, biological, and radiological features at diagnosis and during a forty-month follow-up. RESULTS: Of 47 patients suffering from retroperitoneal fibrosis, 21 patients had idiopathic retroperitoneal fibrosis. Among them, 13 experienced one or more relapses during follow-up. At diagnosis, clinical characteristics, relevant comorbidities, biological and radiological features were similar between groups. Smoking cessation seems associated with decreased relapse risk (p: 0.0624). A total of 8 patients developed chronic renal failure during follow-up. Ureteral infiltration at diagnosis was associated with evolution to chronic renal failure (p: 0.0091). CONCLUSION: No clinical, biological, or radiological features could predict relapse at retroperitoneal fibrosis diagnosis, but smoking cessation may prevent relapse.

Outcomes of patients with hematologic malignancies and COVID-19: a systematic review and meta-analysis of 3377 patients.

Outcomes for patients with hematologic malignancy infected with COVID-19 have not been aggregated. The objective of this study was to perform a systematic review and meta-analysis to estimate the risk of death and other important outcomes for these patients. We searched PubMed and EMBASE up to 20 August 2020 to identify reports of patients with hematologic malignancy and COVID-19. The primary outcome was a pooled mortality estimate, considering all patients and only hospitalized patients. Secondary outcomes included risk of intensive care unit admission and ventilation in hospitalized patients. Subgroup analyses included mortality stratified by age, treatment status, and malignancy subtype. Pooled prevalence, risk ratios (RRs), and 95% confidence intervals (CIs) were calculated using a random-effects model. Thirty-four adult and 5 pediatric studies (3377 patients) from Asia, Europe, and North America were included (14 of 34 adult studies included only hospitalized patients). Risk of death among adult patients was 34% (95% CI, 28-39; N = 3240) in this sample of predominantly hospitalized patients. Patients aged ≥60 years had a significantly higher risk of death than patients <60 years (RR, 1.82; 95% CI, 1.45-2.27; N = 1169). The risk of death in pediatric patients was 4% (95% CI, 1-9; N = 102). RR of death comparing patients with recent systemic anticancer therapy to no treatment was 1.17 (95% CI, 0.83-1.64; N = 736). Adult patients with hematologic malignancy and COVID-19, especially hospitalized patients, have a high risk of dying. Patients ≥60 years have significantly higher mortality; pediatric patients appear to be relatively spared. Recent cancer treatment does not appear to significantly increase the risk of death.

Risk of scleroderma according to the type of immune checkpoint inhibitors.

INTRODUCTION: Immune checkpoint inhibitors (ICIs) are associated with immune-related adverse events (irAEs). Among them, ICIs-induced systemic sclerosis (SSc) is poorly known. METHODS: To better characterize this irAE, our comprehensive approach combined the description of ICIs-induced scleroderma cases, the systematic review of the literature and the analysis of VigiBase, the WHO pharmacovigilance database. RESULTS: We identified two cases with underlying limited cutaneous SSc who presented a dramatic increase in the skin thickening following pembrolizumab, associated with scleroderma renal crisis in one case. In the literature, four cases of scleroderma and four cases of morphea have been reported with pembrolizumab or nivolumab. None following ipilimumab, atezolizumab or durvalumab were retrieved. Skin changes appeared or worsened more quickly with pembrolizumab than nivolumab, and had different patterns between both drugs. Patients with generalized skin changes required high-dose prednisone to improve skin thickening. Among the 2527 scleroderma cases identified in VigiBase, 35 were associated with ICIs. Nivolumab and pembrolizumab showed a disproportionality in scleroderma reporting. No disproportionality was found for ipilimumab, atezolizumab or durvalumab. CONCLUSION: The risk of scleroderma or fibrosis extension in SSc patients should be considered when initiating anti-PD-1 agents. It suggests the role of PD-1/PD-L1 interaction in the pathophysiology of SSc.