Consensus guidelines for the diagnosis and clinical management of Erdheim-Chester disease

A somatic mutation in erythro-myeloid progenitors causes neurodegenerative disease

The pathophysiology of neurodegenerative diseases is poorly understood, and therapeutic options are few. Neurodegenerative diseases are hallmarked by progressive neuronal dysfunction and loss, associated with chronic glial activation¹. Whether microglial activation, which is viewed in general as a secondary process, is detrimental or protective in neurodegeneration remains unclear^1–8. Late-onset neurodegenerative disease observed in patients with histiocytoses^9–12, which are clonal myeloid diseases associated with somatic mutations in the RAS/MEK/ERK pathway such as BRAF^{V600E 13–17}, suggests a possible role of somatic mutations in myeloid cells in neurodegeneration. Yet expression of BRAF^V600E in the hematopoietic stem cell (HSC) lineage causes leukemic and tumoral diseases but not neurodegenerative disease^18,19. Microglia belong to a lineage of adult tissue-resident myeloid cells that develop during organogenesis from yolk sac erythro-myeloid progenitors (EMP) distinct from HSC^20–23. We thus hypothesized that a somatic BRAF^V600E mutation in the EMP lineage may cause neurodegeneration. Here we show that mosaic expression of BRAF^V600E in EMP results in clonal expansion of tissue-resident macrophages and a severe late-onset neurodegenerative disorder, associated with accumulation of ERK-activated amoeboid microglia in mice, also observed in human histiocytoses patients. In the murine model, neurobehavioral signs, astrogliosis, amyloid precursor protein deposition, synaptic loss and neuronal death were driven by ERK-activated microglia and were preventable by BRAF inhibition. These results identify the fetal precursors of tissue-resident macrophages as a potential cell-of-origin for histiocytoses, and demonstrate in mice that a somatic mutation in the EMP lineage can drive late-onset neurodegeneration. Moreover, these data identify activation of the MAP kinase pathway in microglia as a cause of neurodegeneration, and provide opportunities for therapeutic intervention aimed at preventing neuronal death in neurodegenerative diseases.

A Fatal Case of Erdheim-Chester Disease with Hepatic Involvement

Erdheim-Chester disease (ECD) is a rare form of systemic histiocytosis, typically presenting with striking osseous involvement characterized by bilateral osteosclerosis and involvement of organs such as the lung, pituitary gland, heart, and brain. Liver involvement with ECD is extremely uncommon. We report a 56-year-old woman presenting with newly diagnosed cirrhosis and signs concerning for intra-abdominal malignancy, including omental caking and peritoneal thickening. Liver biopsy demonstrated xanthogranulomatous infiltration from ECD. The patient showed initial improvement with interferon therapy, but she developed severe depression, which led to the discontinuation of the treatment. Shortly afterward, she died from progressive liver dysfunction resulting in hepatorenal syndrome.

An unusual case of interstitial lung disease in a patient with cardiopulmonary syndrome as the initial presentation of Erdheim-Chester disease

Erdheim-Chester disease (ECD) is a very rare disorder with only approximately 600 cases reported in the literature. ECD has been recently reclassified as a histiocytic dendritic cell neoplasm. The clinical spectrum ranges from asymptomatic tissue accumulation of histiocytes to invasive tissue infiltration, which can cause fulminant multisystem failure. It typically presents with bone pain and constitutional symptoms. Extraosseous manifestations are not uncommon. ECD-associated interstitial lung disease has been described in 20%-35% of patients. Diagnosis is primarily by tissue biopsy and immunohistochemistry showing xanthogranulomas composed of foamy histiocytes that stain positive for CD68, CD14 and CD163 and negative for CD1á and langerin. We report a case of ECD in a young man with cardiopulmonary involvement who presented with haemoptysis and dyspnoea.

Hematopoietic origin of Langerhans cell histiocytosis and Erdheim-Chester disease in adults

Langerhans cell histiocytosis (LCH) and Erdheim-Chester disease (ECD) are rare histiocytic disorders induced by somatic mutation of MAPK pathway genes. BRAFV600E mutation is the most common mutation in both conditions and also occurs in the hematopoietic neoplasm hairy cell leukemia (HCL). It is not known if adult LCH or ECD arises from hematopoietic stem cells (HSCs), nor which potential blood borne precursors lead to the formation of histiocytic lesions. In this study, BRAFV600E allele-specific polymerase chain reaction was used to map the neoplastic clone in 20 adults with LCH, ECD, and HCL. BRAFV600E was tracked to classical monocytes, nonclassical monocytes, and CD1c+ myeloid dendritic cells (DCs) in the blood, and mutations were observed in HSCs and myeloid progenitors in the bone marrow of 4 patients. The pattern of involvement of peripheral blood myeloid cells was indistinguishable between LCH and ECD, although the histiocytic disorders were distinct to HCL. As reported in children, detection of BRAFV600E in peripheral blood of adults was a marker of active multisystem LCH. The healthy counterparts of myeloid cells affected by BRAF mutation had a range of differentiation potentials depending on exogenous signals. CD1c+ DCs acquired high langerin and CD1a with granulocyte-macrophage colony-stimulating factor and transforming growth factor β alone, whereas CD14+ classical monocytes required additional notch ligation. Both classical and nonclassical monocytes, but not CD1c+ DCs, made foamy macrophages easily in vitro with macrophage colony-stimulating factor and human serum. These studies are consistent with a hematopoietic origin and >1 immediate cellular precursor in both LCH and ECD.

Erdheim-Chester Disease Involving the Central Nervous System with the Unique Appearance of a Coated Vertebral Artery

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis. It is characterized by multiple xanthogranulomatous masses throughout the body, predominantly in the tibia. One of the characteristic radiological findings of the lesions associated with ECD is a “coated artery,” which is often observed in the aorta. Although approximately one-fourth of ECD cases involve the central nervous system (CNS), an intracranial-coated artery has only been reported in four cases. We report a case of ECD that involves the CNS and has the unique appearance of a coated vertebral artery (VA). These tumors entirely encase the bilateral VAs without stenosis and are attached to the dura. Cranial magnetic resonance imaging also showed multiple extra-axial tumors in the cavernous sinus, the frontal convexity, and the orbital cavity. Further investigation revealed additional extracranial lesions around the cervical carotid artery, at the bilateral tibia, and at the elbow joint. A biopsy of the cervical and tibial lesions confirmed ECD. Steroid therapy resulted in a month-long improvement of preoperative symptoms. However, the patient’s condition gradually progressed and he died of pneumonia 1 year after ECD diagnosis. The encasement of the intracranial artery by the tumor without stenosis and the dural attachment suggest ECD, which requires whole body investigation.

Erdheim-Chester Disease Presenting with Secondary Hypertension as a Result of Bilateral, Proximal Renal Artery Stenosis: A Case Report

Erdheim-Chester disease (ECD) is a rare, non-Langerhans cell histiocytosis presenting most commonly with bone and central nervous system symptoms, including but not limited to bone pain and diabetes insipidus. We present a known case of ECD, which was referred for secondary hypertension workup and diagnosed with severe, proximal, bilateral renal artery stenosis.

Erdheim-Chester Disease: Case Report with Aggressive Multisystem Manifestations and Review of the Literature

Erdheim-Chester disease (ECD) is an extremely rare and aggressive form of non-Langerhans cell histiocytosis. ECD usually presents with bone pain in adults aged 40-60. Its etiology is unknown but it is thought to be either a reactive or neoplastic disorder. Recently, mutation of the proto-oncogene BRAF (BRAFV600E) has been found in more than 50% of cases. The multisystemic form of ECD is associated with significant morbidity, which may arise due to histiocytic infiltration of critical organ systems. The common sites of involvement are the skeleton, central nervous system, cardiovascular system, lungs, retroperitoneum, and skin. Current available treatment is interferon alpha as the first line of treatment. Treatment with other agents is based on anecdotal case reports. Cladribine, anakinra, and vemurafenib (BRAF inhibitor) are currently advocated as promising second-line treatments for patients whose response to interferon alpha is unsatisfactory. Herein, we are reporting a middle-aged Saudi male patient with an aggressive type of ECD and highlighting the clinical, radiological, and pathological manifestations associated with ECD and the various treatment options and patient follow-up.

Histiocytoses: emerging neoplasia behind inflammation

Histiocytoses are disorders characterised by inflammation and the accumulation of cells derived from the monocyte and macrophage lineages, which results in tissue damage. Although they are often considered rare disorders with protean clinical manifestations, considerable advances in the understanding of their genetics have led to increased clinical recognition of these conditions, and fuelled further insights into their pathogenesis. In this Review, we describe insights into the cells of origin, molecular pathology, clinical features, and treatment strategies for some of the most common histiocytic disorders, including Langerhans cell histiocytosis, Erdheim-Chester disease, and Rosai-Dorfman disease. With the discovery of recurrent mutations affecting the mitogen-activated protein kinase and mTOR-AKT pathways in some of these histiocytoses, our understanding of these diseases has now evolved from the concept of a primary inflammatory condition to that of a clonal neoplastic disease. This understanding has led to the development of effective mechanism-based therapeutic strategies for patients with histiocytic diseases.

BRAF V600E mutation in pediatric intracranial and cranial juvenile xanthogranuloma

Juvenile xanthogranuloma (JXG) is a cutaneous form of non-Langerhans cell histiocytosis, primarily affecting children. The lesion is presumed to originate from either macrophages or dermal dendritic cells. JXG can rarely present as an isolated intracranial lesion and, in contrast to the dismal outcome of patients with systemic disease, cranial JXG has been shown to carry a more favorable prognosis. Here, we report for the first time 3 pediatric cases of JXG with a BRAF V600E mutation, 2 with intracranial lesions and 1 with cranial lesions. Although these intracranial/cranial lesions have been referred to as JXG, they likely differ from cutaneous JXG in both the clinical features and BRAF status. It may be more appropriate to classify intracranial/cranial JXG in the same group as Langerhans cell histiocytosis and Erdheim-Chester disease, which also have a BRAF V600E mutation. Further study of BRAF status in a larger series of JXG is warranted.

Targeting the interleukin-1 pathway in patients with hematological disorders

Interleukin-1α (IL-1α) and IL-1β are potent inflammatory cytokines that activate local and systemic inflammatory processes and are involved in protective immune responses against infections. However, their dysregulated production and signaling can aggravate tissue damage during infection, inflammatory diseases, and chemotherapy-induced intestinal mucositis. Additionally, cytokines of the IL-1 family play an important role in homeostatic as well as "emergency" hematopoiesis and are involved in the pathogenesis of several myeloid and lymphoid hematological malignancies. In the pathogenesis of intestinal mucositis and graft-versus-host disease (GVHD), these cytokines are considered pivotal during the initiation as well as propagation phase, and insights from animal studies suggest that targeting the IL-1 pathway can significantly ameliorate mucositis and GVHD. Moreover, IL-1α and IL-1β might prove to be valuable targets for both prevention and treatment of cancer and cancer therapy-related complications, and the first clinical studies have already been performed in the setting of hematological malignancies. In this review, we will discuss the role of cytokines of the IL-1 family in hematological malignancies, chemotherapy-induced intestinal mucositis, and GVHD, and speculate on possibilities of therapeutically targeting the IL-1 pathway in hematological patients.

Erdheim-Chester disease associated with a novel, complex BRAF p.Thr599_Val600delinsArgGlu mutation

BRAF mutation testing to determine eligibility for treatment with vemurafenib was performed on archival skin lesions of a 54-year-old patient diagnosed with Erdheim-Chester disease (ECD) in 1999. Sanger sequencing of DNA extracted from a 2008 skin lesion identified two non-contiguous base substitutions in BRAF, which were shown by next-generation sequencing (NGS) to be located in the same allele. Due to its long-standing duration, molecular evolution of disease was possible; however, both Sanger and NGS of a 2000 skin lesion were unsuccessful due to the poor quality of DNA. Finally, droplet digital PCR using a probe specific for this novel mutation detected the complex BRAF mutation in both the 2000 and 2008 lesions, indicating this case to be ECD with a novel underlying BRAF p.Thr599_Val600delinsArgGlu mutation. Although well at present, molecular modelling of the mutant BRAF suggests suboptimal binding of vemurafenib and hence reduced therapeutic effectiveness.

Tocilizumab in patients with multisystem Erdheim-Chester disease

Treatment of Erdheim-Chester disease (ECD), a rare non-Langerhans histiocytosis, relies on interferon-α, chemotherapeutic agents such as purine analogs, cytokine-blocking agents and BRAF inhibitors. Since interleukin (IL)-6 levels are elevated in serum and lesions of ECD patients, we evaluated the therapeutic efficacy and safety of IL-6 blockade with tocilizumab. We conducted an open-label, single-arm, phase II, prospective study of tocilizumab in three patients with multisystem ECD and poor tolerance/contraindications to IFN-α. Modifications of symptoms attributed to ECD represented the criteria for evaluation of clinical response. Changes at positron emission tomography scan, computed tomography scan, and magnetic resonance imaging at month 6 represented the main criteria for the evaluation of radiological response. Sustained complete clinical response and partial radiological improvement were observed in two patients, paralleled by modulation of systemic pro-inflammatory mediators. In spite of disease stabilization or improvement at extra-neurological sites, a third patient experienced a radiologic and clinical progression of central nervous system involvement, mirrored by a dramatic increase of circulating IL-6 and related cytokines. These findings indicate that IL-6 inhibition can be effective in ECD, but caution is advisable in patients with neurologic involvement. IL-6 emerges as a central mediator in ECD pathogenesis.

Three Cases of Erdheim-Chester Disease With Intraocular Manifestations: Imaging and Histopathology Findings of a Rare Entity

PURPOSE

To report intraocular manifestations of Erdheim-Chester Disease (ECD) with multimodal imaging.

DESIGN

A retrospective observational case series.

METHODS

This was a multicenter case series of 3 patients with confirmed tissue diagnosis of ECD that showed intraocular manifestations and were imaged at baseline and follow-up visits.

RESULTS

Intraocular manifestations are rarely observed in association with ECD. Intraocular manifestations of ECD seen on multimodal imaging include histiocytic choroidal infiltration causing choroidal lesions, complicated by recurrent serous retinal detachment (SRD). Short-term resolution of SRD was observed with ocular therapies including intravitreal injections of anti-vascular endothelial growth factor or verteporfin photodynamic therapy in combination with systemic chemotherapy therapies and oral corticosteroids; however, recurrences were common. Chorioretinal biopsy confirmed the diagnosis of ECD in 1 case, with the presence of histiocytic infiltration, fibrosis, and characteristic immunohistologic staining. In another case, with a novel ARAF positive mutation, treatment with sorafenib showed regression of the choroidal lesions and resolution of the SRD on multimodal imaging. These lesions were previously resistant to other forms of therapy.

CONCLUSIONS

Rare intraocular manifestations of ECD confirmed on histopathology can be imaged with multimodal imaging. We report 3 cases, including 1 case diagnosed through histology from chorioretinal biopsy and another case associated with a novel ARAF mutation responsive to targeted therapy with sorafenib. The identification of novel somatic mutation associated with ECD enabled treatment with a new-targeted systemic agent. Multimodal imaging in these cases can also be used to monitor response to therapy.

Comparative Study of Clinical, Pathological, Radiological, and Genetic Features of Patients With Adult Ocular Adnexal Xanthogranulomatous Disease, Erdheim-Chester Disease, and IgG4-Related Disease of the Orbit/Ocular Adnexa

PURPOSE

To compare and contrast the clinical, radiologic, pathologic, and genetic features of patients with ocular adnexal IgG4-related disease (IgG4-RD) and patients with adult ocular adnexal xanthogranulomatous disease (XG).

METHODS

This retrospective review study identified patients with histological evidence of either disease from records of the pathology department of our hospital from 1996 to 2014. Clinical, imaging, and a variety of histopathologic features were collected for 23 patients with IgG4-RD and 13 patients with XG. Next generation sequencing with a 50-gene cancer screening panel was performed on biopsy tissues from 10 patients in each group.

RESULTS

Statistical differences between the 2 groups include eyelid (67%; p = 0.0002) and anterior orbital (75%; p = 0.0352) predilection for XG except for Erdheim-Chester disease subgroup which was more posterior and diffuse. Eyelid involvement was rare (4%) for IgG4-RD. Involvement of orbital nerves was seen in 30% of IgG4-RD and 0% in XG (p = 0.0695). Five patients with IgG4-RD developed malignancy (4 lymphoma, 1 leiomyosarcoma), but none of XG patients. Discriminating pathological features were the presence of any IgG4+ plasma cells (p = 0.0121) and the ratio of IgG4+/IgG+ plasma cells (p =0.0294) for IgG4-RD. Five of 12 (42%) patients with XG had sufficient numbers of IgG4+ plasma cells/high power field to fulfill published diagnostic criteria for IgG4-RD, and 5 (42%) had a ratio of IgG4+/IgG+ plasma cells over 40%, but the numbers overall were less than seen in the IgG4-RD patients. The only genetic difference between the 2 groups was that BRAF V600E mutation was found in 1 of the 2 Erdheim-Chester disease patients, which form a subgroup of XG.

CONCLUSIONS

IgG4-RD and XG share clinical, imaging, and histopathological features including IgG4+ plasma cells. Significant differences were the eyelid involvement in XG, orbital nerve involvement, and an elevated IgG4+/IgG+ ratio in IgG4-RD and the only genetic abnormality found was BRAF V600E mutation in the Erdheim-Chester disease subgroup of XG.

[Usefulness of nuclear medicine in Erdheim-Chester disease: A Lille experience]

INTRODUCTION

Erdheim-Chester disease is a rare form of non-langerhans histiocytosis and its etiology is still not well established. The aims of the study were to assess the value of the bone scintigraphy and the ¹⁸F-FDG PET/CT for the diagnostic and for the latter in the therapeutic evaluation.

METHODS

We retrospectively reviewed 49 patients suspected of Erdheim-Chester disease between 2004 and 2016. Bone scintigraphy was compared with histopathology and PET-CT to conventional morphological examinations and bone scintigraphy. For therapeutic evaluation, thresholds similar to PERCIST 1.0 were used.

RESULTS

Forty-nine bone scintigraphy were evaluated with a sensitivity of 100%, a specificity 97%, a positive predictive value 90% and a negative predictive value of 100%. Eight patients had at least an initial PET-CT. The sensitivity compared to conventional morphological examinations differed from the location but was excellent for orbital, bone and vascular involvements. Specificity was comparable between the different examinations. Six patients treated with interferon^® and three with vemurafenib^® were followed by PET-CT. PET-CT, in agreement to clinicobiological data, identified 4 partial responses and one complete response with interferon^® et two partial responses and one complete response with vemurafenib^®.

CONCLUSION

Our retrospective study suggests that bone scintigraphy and 18F-FDG PET/CT could be useful in the initial assessment of Erdheim-Chester disease but also for the latter in the therapeutic evaluation.

Adult Xanthogranulomatous Disease of the Orbit: Clinical Presentations, Evaluation, and Management

Adult xanthogranulomatous disease of the orbit refers to a heterogeneous group of clinical syndromes with differing degrees of systemic involvement and distinct prognoses. The different syndromes all present clinically with progressively enlarging, yellowish lesions of the orbit. Histologically, the lesions are characterized by an inflammatory infiltrate of foam cells and Touton-type multinucleated giant cells. The xanthomatized histiocytes are CD68⁺, S100^-, and CD1a^-. There are 4 clinical forms of xanthogranulomatous disease of the orbit: adult xanthogranulomatous disease of the orbit, adult onset asthma and periocular xanthogranuloma, necrobiotic xanthogranuloma, and Erdheim-Chester disease. The treatment of local lesions are treated with systemic corticosteroids and other immunosuppressors. Vemurafenib, tocilizumab, and sirolimus have shown promising results in systemic disease.

Real-time genomic profiling of histiocytoses identifies early-kinase domain BRAF alterations while improving treatment outcomes

Many patients with histiocytic disorders such as Langerhans cell histiocytosis (LCH) or Erdheim-Chester disease (ECD) have treatment-refractory disease or suffer recurrences. Recent findings of gene mutations in histiocytoses have generated options for targeted therapies. We sought to determine the utility of prospective sequencing of select genes to further characterize mutations and identify targeted therapies for patients with histiocytoses. Biopsies of 72 patients with a variety of histiocytoses underwent comprehensive genomic profiling with targeted DNA and RNA sequencing. Fifteen patients (21%) carried the known BRAF V600E mutation, and 11 patients (15%) carried various mutations in MAP2K1, which we confirm induce constitutive activation of extracellular signal-regulated kinase (ERK) and were sensitive to inhibitors of mitogen-activated protein kinase kinase (MEK, the product of MAP2K1). We also identified recurring ALK rearrangements, and 4 LCH patients with an uncommon in-frame deletion in BRAF (N486_P490del or N486_T491>K), resulting in constitutive activation of ERK with resistance to V600E-specific inhibitors. We subsequently describe clinical cases where patients with aggressive multisystem LCH experience dramatic and sustained responses to monotherapy with either dabrafenib or trametinib. These findings support our conclusion that comprehensive genomic profiling should be regularly applied to these disorders at diagnosis, and can positively impact clinical care.

The clinical spectrum of Erdheim-Chester disease: an observational cohort study

Erdheim-Chester Disease (ECD) is a rare, potentially fatal, multi-organ myeloid neoplasm occurring mainly in adults. The diagnosis is established by clinical, radiologic, and histologic findings; ECD tumors contain foamy macrophages that are CD68+, CD163+, CD1a-, and frequently S100-. The purpose of this report is to describe the clinical and molecular variability of ECD. Sixty consecutive ECD patients (45 males, 15 females) were prospectively evaluated at the NIH Clinical Center between 2011 and 2015. Comprehensive imaging and laboratory studies were performed, and tissues were examined for BRAF V600E and MAPK pathway mutations. Mean age at first manifestations of ECD was 46 years; a diagnosis was established, on average, 4.2 years after initial presentation. Bone was the most common tissue affected, with osteosclerosis in 95% of patients. Other manifestations observed in one-third to two-thirds of patients include cardiac mass and periaortic involvement, diabetes insipidus, retro-orbital infiltration, retroperitoneal, lung, CNS, skin and xanthelasma, usually in combination. Methods of detection included imaging studies of various modalities. Mutation in BRAF V600E was detected in 51% of 57 biopsies. One patient had an ARAF D228V mutation, and one had an activating ALK fusion. Treatments included interferon alpha, imatinib, anakinra, cladribine, vemurafenib and dabrafenib with trametinib; eleven patients received no therapy. The diagnosis of ECD is elusive because of the rarity and varied presentations of the disorder. Identification of BRAF and other MAPK pathway mutations in biopsies improves ECD diagnosis, allows for development of targeted treatments, and demonstrates that ECD is a neoplastic disorder.

Erdheim-Chester Disease With Renal Involvement: A Case Report

Erdheim-Chester disease is a type of non-Langerhans cell histiocytosis. It is a rare, multisystem disorder with unknown etiology. Heterogeneity of the clinical symptoms makes the diagnosis challenging. On the other hand, knowing the signs and radiological findings of the disease helps to establish a correct diagnosis. In this article, we present a 51-year-old male patient with skeletal and urinary system manifestations who finally underwent right nephrectomy due to renal insufficiency. The diagnosis was suspected by the retroperitoneal infiltrative process and radiological findings of the tubular bones. Erdheim-Chester disease diagnosis was confirmed with CD68(+) CD1a(-) histiocytes detected by immunohistochemical analysis of the nephrectomy specimen.

Acid Ceramidase Deficiency is characterized by a unique plasma cytokine and ceramide profile that is altered by therapy

Acid Ceramidase Deficiency (Farber disease, FD) is an ultra-rare Lysosomal Storage Disorder that is poorly understood and often misdiagnosed as Juvenile Idiopathic Arthritis (JIA). Hallmarks of FD are accumulation of ceramides, widespread macrophage infiltration, splenomegaly, and lymphocytosis. The cytokines involved in this abnormal hematopoietic state are unknown. There are dozens of ceramide species and derivatives, but the specific ones that accumulate in FD have not been investigated. We used a multiplex assay to analyze cytokines and mass spectrometry to analyze ceramides in plasma from patients and mice with FD, controls, Farber patients treated by hematopoietic stem cell transplantation (HSCT), JIA patients, and patients with Gaucher disease. KC, MIP-1α, and MCP-1 were sequentially upregulated in plasma from FD mice. MCP-1, IL-10, IL-6, IL-12, and VEGF levels were elevated in plasma from Farber patients but not in control or JIA patients. C16-Ceramide (C16-Cer) and dhC16-Cer were upregulated in plasma from FD mice. a-OH-C18-Cer, dhC12-Cer, dhC24:1-Cer, and C22:1-Cer-1P accumulated in plasma from patients with FD. Most cytokines and only a-OH-C18-Cer returned to baseline levels in HSCT-treated Farber patients. Sphingosines were not altered. Chitotriosidase activity was also relatively low. A unique cytokine and ceramide profile was seen in the plasma of Farber patients that was not observed in plasma from HSCT-treated Farber patients, JIA patients, or Gaucher patients. The cytokine profile can potentially be used to prevent misdiagnosis of Farber as JIA and to monitor the response to treatment. Further understanding of why these signaling molecules and lipids are elevated can lead to better understanding of the etiology and pathophysiology of FD and inform development of future treatments.

Lymphoma classification update: T-cell lymphomas, Hodgkin lymphomas, and histiocytic/dendritic cell neoplasms

INTRODUCTION

Lymphomas are classified based on the normal counterpart, or cell of origin, from which they arise. Because lymphocytes have physiologic immune functions that vary both by lineage and by stage of differentiation, the classification of lymphomas arising from these normal lymphoid populations is complex. Recent genomic data have contributed additional depth to this complexity. Areas covered: Lymphoma classification follows the World Health Organization (WHO) system, which reflects international consensus and is based on pathological, genetic, and clinical factors. The present review focuses on the classification of T-cell lymphomas, Hodgkin lymphomas, and histiocytic and dendritic cell neoplasms, summarizing changes reflected in the 2016 revision to the WHO classification. These changes are critical to hematologists and other clinicians who care for patients with these disorders. Expert commentary: Lymphoma classification is a continually evolving field that needs to be responsive to new clinical, pathological, and molecular understanding of lymphoid neoplasia. Among the entities covered in this review, the 2016 revisions in the WHO classification particularly impact T-cell lymphomas, including a new umbrella category of T-follicular helper cell-derived lymphomas and evolving recognition of indolent T-cell lymphomas and lymphoproliferative disorders.

Effective BRAF inhibitor vemurafenib therapy in a 2-year-old patient with sequentially diagnosed Langerhans cell histiocytosis and Erdheim-Chester disease

Erdheim-Chester disease (ECD) is a rare histiocytic disorder, characterized by the xanthomatous infiltration of tissues by CD68-positive and CD1a-/CD100-negative foamy histiocytes. In childhood, ECD is exceptionally rare, and only a dozen cases have been published so far. The cooccurence of Langerhans cell histiocytosis (LCH) and ECD is even rarer. Here, we report a 2-year-old boy, the youngest patient in the literature so far, who was diagnosed with concomitant BRAF mutation-positive LCH and ECD. In his case, conventional LCH treatment proved to be ineffective, but he is the youngest patient who was successfully treated with the BRAF inhibitor vemurafenib.

An unusual thoracic localizations of Erdheim- Chester disease: A case report

Erdheim- Chester disease is a rare non- Langerhans cell histiocytosis that usually involves the bones, heart, central nervous system, retroperitoneum, eyes, kidneys, skin and adrenals. Lungs are affected in up to one-half cases; at CT scan various patterns are described: interstitial disease, consolidations, micronodules and microcysts, with or without pleural involvement. We presented a case of a 59 year-old man with unusual intrathoracic manifestation of Erdheim- Chester disease. Singularities of our report are the lonely thoracic involvement at the onset of the disease and a histiocytic lesion in the posterior mediastinum.

Isolated pulmonary involvement in Erdheim-Chester disease

Erdheim–Chester disease is a rare non-Langerhans cell histiocytic disorder. It is primarily a disease of the long bones. Pulmonary involvement in systemic disease is detected in about half the reported cases. Isolated lung involvement is extremely rare with no clear recommendations for treatment. A 52-year-old caucasian male was evaluated for 1.9 cm × 1.6 cm spiculated nodule in the right upper lobe. Pulmonary function testing and bronchoscopy with endobronchial ultrasound, transbronchial biopsy, and microbiology were inconclusive. Positron emission tomography–computed tomography (PET-CT) was significant for the avidity in same lung nodule along with mediastinal and hilar adenopathy but no bone involvement. Wedge resection with histopathology and immunohistochemistry reported a fibrohistiocytic infiltrate in bronchovascular distribution which was positive for CD68 and negative for CD1A, S100, and BRAF V600E mutation. Magnetic resonance imaging brain ruled out central nervous system involvement. The rarity of the condition along with the complex pathology makes it difficult to diagnose and hence intervene appropriately.

Targeted treatment of brainstem neurohistiocytosis guided by urinary cell-free DNA

OBJECTIVE

To identify a treatment-responsive BRAFV600E mutation in brainstem neurohistiocytosis, where no lesional tissue was readily obtainable, using a cell-free DNA approach.

METHODS

Cell-free DNA was extracted from urine and allele-specific PCR for the BRAFV600E mutation was performed. Response to conventional treatment (corticosteroids and interferon) and targeted treatment with a BRAF inhibitor was assessed by clinical evaluation, gadolinium-enhanced MRI brain scan, and serial testing of urinary cell-free DNA for mutant alleles.

RESULTS

BRAFV600E mutation could be readily identified in urinary cell-free DNA at an allele frequency of 4.2%. Treatment of Erdheim-Chester disease with corticosteroids and interferon was ineffective and associated with disease progression. Treatment with BRAF inhibitors was associated with clinical improvement and near-complete radiologic remission. Following 6 months of BRAF inhibitor therapy, no enhancing lesions could be detected in the brain and mutant alleles were cleared from the urine.

CONCLUSIONS

Analysis of urinary cell-free DNA using allele-specific PCR for BRAFV600E mutations allows rapid noninvasive identification of a highly treatment-responsive pathway, leading to clinical and radiologic remission of disease. Our case demonstrates that this assay may have a particular role in challenging neurohistiocytosis cases, where attempts at obtaining lesional tissue have failed or are not feasible.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence. This is a single observation study without controls.

A Unique Case of Erdheim-Chester Disease With Cervical and Lumbosacral Nerve Involvement: FDG PET/CT Finding

Cervical and lumbosacral nerve roots and plexus involvement in Erdheim-Chester disease (ECD) is rare. A 50-year-old man with progressive edema in bilateral lower extremities, numbness, weakness, and muscle atrophy of upper limb for 2 years had been misdiagnosed of neuritis or cervical spondylosis until he presented bone pain. In addition to bilateral symmetric involvement in long bones, bilateral hypermetabolism in cervical and lumbosacral nerve roots was found by FDG PET/CT scan. ECD was diagnosed by bone biopsy. This case reported the rare peripheral neural involvement and highlighted the advantage of FDG PET/CT scan in evaluating the multisystem involvement of ECD.

Erdheim-Chester disease, moving away from the orphan diseases: A case report

With approximately 750 cases reported, Erdheim-Chester disease is an exceedingly rare histiocyte cell disorder. Affected sites typically include long bones, large vessels and central nervous system. However, cutaneous and pulmonary involvement can also occur. The diagnosis is ascertained by identification of foamy histiocytes positive for CD68, CD163, and factor XIIIa on immunoperoxidase staining. Recently published literature have described an association between Erdheim-Chester disease and BRAF V600E mutation. This finding prompted the investigation of therapeutic possibilities with BRAF inhibitors, successful agents against other BRAF mutation-positive diseases. Vemurafenib, a BRAF kinase inhibitor, has been shown to be effective in BRAF V600E mutation-positive malignancies, such as NSCLC and melanoma, as well as in several case reports of Erdheim-Chester disease. We report a case of Erdheim-Chester disease diagnosed at our institution, treated with vemurafenib.

Retroperitoneal fibrosis - the state-of-the-art

Retroperitoneal fibrosis (RPF) is a rare disease, hallmarked by inflammation and deposition of fibrous tissue around the abdominal aorta. This process may spread contiguously and involve adjacent structures, leading to many complications, among which the most frequent and most severe is ureteral obstruction. The condition usually has idiopathic origin (idiopathic retroperitoneal fibrosis – IRF), but can also develop secondarily to a number of factors. The etiology of the disease remains unclear. Current research suggests that about half of the cases of IRF may be a symptom of a recently discovered, clinically heterogeneous immunoglobulin G4-related disease (IgG4-RD). Corticosteroids are the first-line treatment for IRF, but effective attempts to use immunosuppressants are also made. This paper presents the current state of knowledge on the etiopathogenesis, clinical presentation, diagnosis and therapeutic possibilities in different forms of RPF. Based on the latest research, an analysis of the relationship between IRF and IgG4-RD was performed.

Systemic vasculitis associated with vemurafenib treatment: Case report and literature review

RATIONALE

Vemurafenib, an inhibitor of mutated B-rapidly accelerated fibrosarcoma, is frequently used in the treatment of melanoma and Erdheim-Chester disease (ECD) patients. Inflammatory adverse effects have been increasingly reported after vemurafenib treatment.

PATIENT CONCERNS AND DIAGNOSE

We report 6 cases of vemurafenib-associated vasculitis, of whom a personal case of a 75-year-old man with history of ECD who developed purpura and rapidly progressive pauci-immune glomerulonephritis during treatment with vemurafenib.

INTERVENTION

In the 5 others cases from the literature, all patients presented skin vasculitis, and with joint involvement in 60% of them. Vemurafenib treatment was stopped (n = 3), continued at reduced doses (n = 1), or continued at the same dose (n = 2).

OUTCOMES

Three patients (50%) received corticosteroids combined with cyclophosphamide (n = 1), and all achieved remission of vasculitis. One patient experienced vasculitis relapse after vemurafenib therapy was restarted.

LESSONS

Systemic vasculitis is a rare vemurafenib-associated adverse event that may be life-threatening.

Erdheim-Chester disease: 25-year history with early CNS involvement

We report a case of Erdheim-Chester disease (ECD) with a 25-year history following initial presentation with diabetes insipidus and brainstem involvement. The exceptionally long history is particularly notable, given that ECD is a life-threatening disorder and there is a recognised association between central nervous system involvement and poor outcome. The case is a timely reminder of the presenting features of the condition, given the emergence of potential new treatment options.

Erdheim-Chester disease with bilateral Achilles tendon involvement

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis with a broad spectrum of organ manifestations, presenting with characteristic radiological and histological findings. Soft tissue manifestations (xanthogranulomas) have been reported to be most commonly found in the region of the orbits. We report bilateral Achilles tendon xanthogramlomas in a 36-year-old male with biopsy-proven and B-RAF V600E-positive ECD. Although rare, ECD should be considered in the differential diagnosis of intratendinous masses.

Erdheim-Chester disease (ECD): Case report, clinical and basic investigations, and review of literature

BACKGROUND

Erdheim-Chester disease (ECD) is an uncommon aggressive, multisystem form of non-Langerhans' cell histocytosis, which was firstly reported by Jakob Erdheim and William chester in 1930. The disease pathological features encompass an aberrant multiplication, overproduction and accumulation of white blood cells called histiocytes within multiple tissues and organs. Herein, we present a case of ECD owing to the rarity of this disease (roughly 550 cases have been described in the literature to date).

METHODS

We discussed the clinical course, diagnostic evaluations, and the possible treatments. Our case was encountered in an Arab male in his 30's who has suffered from an ongoing bones pain for years.

RESULTS

At our rheumatologic department we compiled his recent medical history, which consisted of diagnosis of central diabetes insipidus, hyperprolactinemia and secondary hypogonadism along with the previously conducted laboratory evaluations and imaging which brought to our mind the possibility of an infiltrative disease such as ECD. The diagnosis of ECD was done based on the combinations of pathognomonic radiographic osteosclerosis, neuroimaging, bones biopsies along with a careful clinical evaluation. Given the protean clinical manifestations, interferon-α was considered as our first line treatment of ECD, consequently our patient improved noticeably.

CONCLUSION

Clinical presentation, imaging studies, distinctive pathological findings, followed by bone biopsy showed a non-Langerhans cell histiocytosis, supported by immunohistochemistry exams are essential for the diagnosis. Radiation therapy and Bisphosphonates in addition to cladribine, anakinra, infliximab and vemurafenib (BRAF Inhibitors) are currently advocated as promising second line treatment for patients whose response to interferon-α is unsatisfactory.

A Case of Incidentally-diagnosed Erdheim-Chester Disease

Erdheim-Chester disease (ECD) is a rare multisystemic non-Langerhans cell histiocytosis that may be clonal and inflammatory in origin. The hallmark of the disease is infiltration of various organ systems by CD68+/CD1a- histiocytes containing foamy lipid-laden inclusions. The manifestations and course of the disease are variable and depend on the organ systems that are affected. Patients may be asymptomatic or may develop life-threatening complications, including myocardial infarction. The most common clinical manifestation is lower extremity bone pain. Imaging manifestations of the disease include symmetric osteosclerosis of the distal long bones, circumferentially “coated” aorta, pleural and pericardial thickening/fluid, and perirenal encasement. Treatment for the disease is evolving, particularly with the use of molecular BRAF inhibition. We present a case of a patient with ECD initially suspected based on the imaging manifestations.

Cardiothoracic manifestations of primary histiocytoses

The objectives of this article were: (1) to review common and rare manifestations of systemic and pulmonary Langerhans cell histiocytosis, Rosai-Dorfman disease, Erdheim-Chester disease and juvenile xanthogranuloma; (2) to provide the reader with important pathologic, epidemiologic and clinical features of these diseases. The histiocytoses are a diverse group of diseases which typically manifest with multiorgan involvement. Understanding the pathologic, epidemiologic and clinical features of these entities can help the radiologist suggest an accurate diagnosis of histiocytosis when typical imaging features are encountered.