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

A case of Erdheim-Chester disease with spinal cord compression and sphenoid sinus involvement

Erdheim-Chester disease is a rare form of non-Langerhans cell histiocytosis. It is an inflammatory disorder associated with BRAF V600E mutation in 50% of cases. This multisystem disease is rarely associated with spinal involvement. Neurological involvement is an independent predictive factor of poor prognosis. The diagnosis is histopathological based on CD68-positive and CD1A-negative histiocytes. Treatment with interferon-alpha is an independent predictor of survival in Erdheim-Chester disease and vemurafenib has also been shown to be effective for BRAF V600E mutation. We report a clinical case of a 51-year-old patient with multiple and rare locations of Erdheim-Chester disease, particularly at the sphenoid sinus.

Clinical and Histopathologic Features of Interstitial Lung Disease in Erdheim⁻Chester Disease

Limited information is available regarding interstitial lung disease (ILD) in Erdheim⁻Chester disease (ECD), a rare multisystemic non-Langerhans cell histiocytosis. Sixty-two biopsy-confirmed ECD patients were divided into those with no ILD (19.5%), minimal ILD (32%), mild ILD (29%), and moderate/severe ILD (19.5%), based on computed tomography (CT) findings. Dyspnea affected at least half of the patients with mild or moderate/severe ILD. Diffusion capacity was significantly reduced in ECD patients with minimal ILD. Disease severity was inversely correlated with pulmonary function measurements; no correlation with BRAF V600E mutation status was seen. Reticulations and ground-glass opacities were the predominant findings on CT images. Automated CT scores were significantly higher in patients with moderate/severe ILD, compared to those in other groups. Immunostaining of lung biopsies was consistent with ECD. Histopathology findings included subpleural and septal fibrosis, with areas of interspersed normal lung, diffuse interstitial fibrosis, histiocytes with foamy cytoplasm embedded in fibrosis, lymphoid aggregates, and focal type II alveolar cell hyperplasia. In conclusion, ILD of varying severity may affect a high proportion of ECD patients. Histopathology features of ILD in ECD can mimic interstitial fibrosis patterns observed in idiopathic ILD.

Prognostic factors of Erdheim-Chester disease: a nationwide survey in Japan

Erdheim-Chester disease is a rare histiocytosis with insufficient clinical data. To clarify the clinical features and prognostic factors of Erdheim-Chester disease, we conducted a nationwide survey to collect the detailed data of 44 patients with Erdheim-Chester disease in Japan. The median age of onset of the participants was 51 (range: 23-76) years, and the median number of involved organs per patient was 4 (range: 1-11). The existence of central nervous system disease was correlated with older age (P=0.033), the presence of cardiovascular lesions (P=0.015), and an increased number of involved organs (P=0.0042). The median survival from the onset was 10.4 years, and >3.0 mg/dL C-reactive protein level at onset was associated with worse outcome (median survival, 14.6 vs. 7.4 years; P=0.0016). In a multivariate analysis, age >60 years (hazard ratio, 25.9; 95% confidence interval, 2.82-237; P=0.0040) and the presence of digestive organ involvement (hazard ratio, 4.74; 95% confidence interval, 1.05-21.4; P=0.043) were correlated with worse survival. Fourteen patients had available histological samples of Erdheim- Chester disease lesions. BRAFV600E mutation was detected in 11 patients (78%) by Sanger sequencing. A correlation between BRAF mutation status and clinical factors was not observed. Our study revealed that age and digestive organ involvement influence the outcome of Erdheim-Chester disease patients, and an inflammatory marker, such as C-reactive protein, might reflect the activity of this inflammatory myeloid neoplasm.

Characteristics, outcome and treatments with cranial pachymeningitis: A multicenter French retrospective study of 60 patients

The aim of this study was to determine the characteristics, treatment, and outcome according to each etiology of pachymeningitis.We conducted a retrospective multicenter French nationwide study between 2000 and 2016 to describe the characteristics, outcome, and treatment of pachymeningitis.We included 60 patients (median age 55.5 years; interquartile range [IQR] 30-80, female/male ratio 0.43). Neurologic signs were present in 59 patients (98%) and consisted of headache in 43 (72%), cranial nerve palsy in 33 (55%), confusion in 10 (17%), seizures in 7 (12%), and focal neurologic signs in 9 (15%). Fever and weight loss were present in 8 (13%) and 13 cases (22%), respectively. Cerebral venous thrombosis was present in 8 cases (13%). Analysis of cerebrospinal fluid showed moderate hyperproteinorachia (median 0.68 g/L; IQR 0.46-3.2) with or without pleiocytosis. Diagnosis included idiopathic pachymeningitis (n = 18; 30%); granulomatosis with polyangiitis (n = 13; 17%); Erdheim-Chester disease (n = 10; 17%); IgG4-related disease and tuberculosis (n = 3; 5% each); Rosai-Dofman disease, microscopic polyangiitis, and sarcoidosis (n = 2, 3% each); cryptococcal meningitis, Lyme disease, ear-nose-throat infection, postlumbar puncture, low spinal-fluid pressure syndrome, and lymphoma (n = 1 each). We found no difference in demographics and neurologic presentation among idiopathic pachymeningitis, Erdheim-Chester disease, and granulomatosis with polyangiitis. In contrast, frequencies were lower with idiopathic pachymeningitis than Erdheim-Chester disease for general signs (6% and 40%, respectively, P = .041) and complete neurologic response (0% vs 39%, P = .045).The detection of extraneurologic signs and routine screening are needed to classify the pachymeningitis origin. Prospective studies are warranted to determine the best treatment in each case.

Consensus recommendations for the diagnosis and clinical management of Rosai-Dorfman-Destombes disease

Rosai-Dorfman-Destombes disease (RDD) is a rare non-Langerhans cell histiocytosis characterized by accumulation of activated histiocytes within affected tissues. RDD, which now belongs to the R group of the 2016 revised histiocytosis classification, is a widely heterogeneous entity with a range of clinical phenotypes occurring in isolation or in association with autoimmune or malignant diseases. Recent studies have found NRAS, KRAS, MAP2K1, and ARAF mutations in lesional tissues, raising the possibility of a clonal origin in some forms of RDD. More than 1000 reports have been published in the English literature; however, there is a lack of consensus regarding approach for the clinical management of RDD. Although in most cases RDD can be observed or treated with local therapies, some patients with refractory or multifocal disease experience morbidity and mortality. Here we provide the first consensus multidisciplinary recommendations for the diagnosis and management of RDD. These recommendations were discussed at the 32nd Histiocyte Society Meeting by an international group of academic clinicians and pathologists with expertise in RDD. We include guidelines for clinical, laboratory, pathologic, and radiographic evaluation of patients with RDD together with treatment recommendations based on clinical experience and review of the literature.

Rare diseases of bone: Erdheim-Chester and Rosai-Dorfman non-Langerhans cell histiocytoses

Non-Langerhans cell histiocytosis (N-LCH) summarizes a group of rare diseases with different clinical presentations, pathogenesis and morphology. These include primary cutaneous N-LCH, cutaneous N-LCH with systemic involvement, and primary extracutaneous systemic forms with occasional cutaneous involvement.

The juvenile (JXG) and non-juvenile xanthogranuloma (N-JXG) family of histiocytoses are N-LCH: the JXG family consisting of the JXG (cutaneous), xanthoma disseminatum (cutaneous and systemic) and Erdheim-Chester disease (ECD; systemic); and the N-JXG family consisting of the solitary reticulohistiocytoma (cutaneous), multicentric reticulohistiocytosis (cutaneous and systemic) and Rosai-Dorfman disease (RDD; systemic).

ECD is a clonal disorder from the JXG family of N-LCH; RDD is a reactive proliferative entity from the non-juvenile xanthogranuloma family of N-LCH.

ECD and RDD N-LCH are rare disorders, which are difficult to diagnose, with multi-organ involvement including bone and systemic symptoms, and which respond to therapy in an unpredictable way.

The key to successful therapy is accurate identification at tissue level and appropriate staging. Patients should be observed and monitored in a long-term pattern. Prognosis depends on disease extent and the organs involved; it is generally good for RDD disease and variable for ECD.

Cite this article: EFORT Open Rev 2018;3:381-390. DOI: 10.1302/2058-5241.3.170047

Erdheim-Chester Disease Presenting as an Anterior Mediastinal Tumor without Skeletal Involvement

Erdheim-Chester disease (ECD) is a form of non–Langerhans cell histiocytosis that most commonly involves the skeletal system. We report an unusual case of ECD presenting as an anterior mediastinal tumor without skeletal involvement. A 60-year-old man with no remarkable medical history was referred for evaluation of a mediastinal mass. The patient underwent surgical excision of the tumor via video-assisted thoracoscopic surgery. Histologic examination revealed marked proliferation of atypical histiocytes with sclerosis, and the results of immunohistochemical staining were suggestive of ECD.

Treating Heart Inflammation With Interleukin-1 Blockade in a Case of Erdheim-Chester Disease

Pericarditis is an inflammatory heart disease, which may be idiopathic or secondary to autoimmune or auto-inflammatory diseases and often leads to severe or life-threatening complications. Colchicine and non-steroidal anti-inflammatory drugs represent the mainstay of treatment, whereas use of corticosteroids is associated with recurrence of disease flares. While effective and safe anti-inflammatory therapies remain an unmet clinical need, emerging clinical and experimental evidence points at a promising role of inhibition of the pro-inflammatory cytokine interleukin-1 (IL-1). We thus evaluated treatment with the IL-1 receptor antagonist anakinra in a case of extremely severe pericarditis with cardiac tamponade and heart failure secondary to Erdheim-Chester disease (ECD), a rare clonal disorder of macrophages characterized by rampant inflammation and multiorgan involvement. A 62-year-old man was admitted to the Emergency Department with severe pericardial effusion requiring the creation of a pleuro-pericardial window. A whole-body contrast-enhanced computed tomography pointed at a diagnosis of ECD with involvement of the heart and pericardium and of the retroperitoneal space. Over the following days, an echocardiography revealed a closure of the pleuro-pericardial window and a relapse of the pericardial effusion. Treatment with anakinra, the recombinant form of the naturally occurring IL-1 receptor antagonist, was started at a standard subcutaneous dose of 100 mg/day. After 2 days, we observed a dramatic clinical improvement, an abrupt reduction of the inflammatory markers, and a reabsorption of the pericardial effusion. Anakinra was maintained as monotherapy, and the patient remained asymptomatic in the absence of disease flares for the following year. Recent studies point at inhibition of IL-1 activity as an attractive treatment option for patients with refractory idiopathic recurrent pericarditis. Anakinra treatment may also have a role in patients with pericarditis in the setting of systemic inflammatory disorders, such as ECD.

A Rare Case of Erdheim-Chester Disease (Non-Langerhans Cell Histiocytosis) with Concurrent Langerhans Cell Histiocytosis: A Diagnostic and Therapeutic Challenge

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocyte disorder most commonly characterized by multifocal osteosclerotic lesions of the long bones demonstrating sheets of foamy histiocyte infiltrates on biopsy with or without histiocytic infiltration of extraskeletal tissues. ECD can be difficult to diagnose since it is a very rare disease that can affect many organ systems. Diagnosis is based on the pathologic evaluation of involved tissue interpreted within the clinical context. Patients who have the BRAF V600E mutation are treated first line with vemurafenib. For those without the mutation with symptomatic ECD, conventional or PEGylated interferon alpha is recommended. For patients who are either intolerant or nonresponsive to interferon alpha, systemic chemotherapy with or without corticosteroids can be used. We present a rare case of Erdheim-Chester disease with concurrent Langerhans cell histiocytosis which occurs in only one fifth of the cases and often presents as a diagnostic and therapeutic challenge.

Thoracic involvement in Erdheim-Chester disease: computed tomography imaging findings and their association with the BRAFV600E mutation

OBJECTIVES

To investigate the computed tomography (CT) thoracic findings in Erdheim-Chester disease (ECD) and evaluate the association of these findings with the BRAF^V600E mutation.

METHODS

This was a prospective study of patients with ECD (n=61, men=46) who underwent thoracic CT imaging. CT examinations were independently interpreted by two experienced radiologists. Association of imaging findings with BRAF^V600E was achieved via the Chi-square or Fisher's exact test and odds ratios (OR) with 95% confidence intervals (CI), as appropriate.

RESULTS

Fifty-five ECD patients (90%) showed pulmonary findings, which included interlobular septal thickening (69%), pulmonary nodules (62%), airway thickening (13%) and ground glass opacities (36%). Pulmonary nodules were classified by the pattern of distribution: subpleural regions (36%), lung parenchyma (13%) and both regions (13%). Pleural and mediastinal involvement were present in 15% and 62% of cases, respectively. The most common mediastinal finding was sheathing of the right coronary artery (34%), followed by sheathing of the thoracic aorta (30%). The BRAF^V600E mutation, positive in 31 patients, was associated with the frequency of sheathing of the coronary arteries (p = 0.01).

CONCLUSIONS

Of the thoracic findings reported in this study, we found a statistically significant positive association between the BRAF^V600E mutation and presence of coronary artery sheathing.

KEY POINTS

• To assess the degree of thoracic involvement in ECD with CT. • BRAF ^V600E mutation has a high association with right coronary artery sheathing. • BRAF ^V600E genetic testing detects patients at high risk of developing RCA sheathing.

Superior efficacy and similar safety of double dose anakinra in Erdheim-Chester disease after single dose treatment

Objectives. In Erdheim-Chester disease (ECD), the empirical single dose (SD, 100 mg/day) anakinra sometimes induces only partial responses. Since SD is usually well tolerated, doubling the dose might improve response while maintaining an acceptable safety profile. Methods. A retrospective analysis was performed of outcomes under double-dose (DD) of anakinra in 4 ECD patients who did not exhibit a complete response (CR) under SD treatment. Bone, retroperitoneal, neurologic/orbital, peritoneal, pericardial, right atrium, and pleural involvements were recorded. CR, partial response (PR), stable disease, progressive disease (PD) and tolerance of DD were assessed. Results. SD treatment was a second or third line treatment in three patients after interferon-therapy failure. Two patients, including one with a BRAF mutation, achieved a CR and one patient with a NRAS mutation achieved a PR with DD treatment. The fourth patient, wild-type for both genes, did not respond to a first DD treatment, but then achieved CR under SD associated with a reduced dose of vemurafenib (960 mg/d). Bone and retroperitoneal lesions partially improved on imaging with SD in all patients, but were further improved under DD with two patients achieving CR. With SD treatment, two patients with right atrial masses showed sustained CR. Under DD treatment, two patients with massive serositis refractory to SD, showed PR. Conclusion. DD improved the response to anakinra and lead to two CRs and a PR in three out of four ECD patients, with minor and comparable side-effects to those of SD, while failures were essentially related to massive serositis.

The histopathology of Erdheim-Chester disease: a comprehensive review of a molecularly characterized cohort

Erdheim-Chester disease is a rare, non-Langerhans cell histiocytosis histologically characterized by multi-systemic proliferation of mature histiocytes in a background of inflammatory stroma. The disease can involve virtually any organ system; most commonly the bones, skin, retroperitoneum, heart, orbit, lung, and brain are affected. Although a histiocytic proliferation is the histological hallmark of the disease, a wide range of morphological appearances have been described as part of case studies or small series. A comprehensive review of histopathological features in clinically and molecularly defined Erdheim-Chester disease has yet to be characterized. To address this issue and help guide clinical practice, we comprehensively analyzed the pathological spectrum of Erdheim-Chester disease in a clinically and molecularly defined cohort. We reviewed 73 biopsies from 42 patients showing involvement by histiocytosis from a variety of organ systems, including bone (16), retroperitoneum (11), skin (19), orbit (6), brain (5), lung (6), cardiac structures (2), epidural soft tissue (3), oral cavity (2), subcutaneous soft tissue (2), and testis (2). In eight patients, one or more bone marrow biopsies were performed due to clinical indication and an accompanying myeloid neoplasm was detected in six of them. Thirty-eight cases were investigated for genetic abnormalities. Somatic mutations involving BRAF (25/38), MAP2K1 (6/38), ARAF (2/38), MAP2K2 (1/38), KRAS (1/38), and NRAS (1/38) genes were detected. One of the cases with a MAP2K1 mutation also harbored a PIK3CA mutation. We have observed marked heterogeneity in histology and immunophenotype, identified site-specific features, overlap with other histiocytic and myeloid disorders and potential diagnostic pitfalls. We hope that broadening the spectrum of recognized pathologic manifestations of Erdheim-Chester disease will help practicing clinicians and pathologists to diagnose Erdheim-Chester disease early in the disease course and manage these patients effectively.

An autopsy case report: Differences in radiological images correlate with histology in Erdheim-Chester disease

p16 activation caused by oncogenic mutations may represent oncogene-induced senescence (OIS), a protective mechanism against oncogenic events. However, OIS can contribute to tumor development via tissue remodeling in some tumors. Erdheim-Chester disease (ECD), a rare non-Langerhans cell histiocytosis, is one such tumor. Its clinical and histological features vary, making it difficult to diagnose. Herein, we describe an autopsy of an ECD patient. The patient underwent radiological examinations, including ¹⁸ F-fluorodeoxyglucose (FDG)-positron emission tomography/computed tomography (PET/CT), bone scintigraphy and CT. A biopsy from the lesion with the highest FDG accumulation confirmed the presence of foamy macrophages, a diagnostic clue for ECD. Based on this finding and the clinical features, ECD was diagnosed. However, the patient died from heart dysfunction. After the autopsy, each radiologically different site showed various histological findings regarding the morphology of macrophages, fibrosis, inflammation, and p16 expression. OIS-induced histological progression can cause certain changes observed in radiological images. In addition, in order to evaluate the increase in glucose metabolism, which can affect FDG accumulation, the expression of glucose transporter 1 and hexokinase II was also analyzed. Summarizing the radio-histological correlation can help further both the understanding and diagnosis of ECD.

The fibrogenic chemokine CCL18 is associated with disease severity in Erdheim-Chester disease

Erdheim-Chester disease (ECD) is a rare histiocytosis, characterized by xanthogranulomatous tissue infiltration by foamy histiocytes. Fibrosis, a histologic hallmark of ECD, is responsible for lesion growth and clinical manifestations. Unraveling molecular fibrotic pathway in ECD would allow the identification of new pharmacologic targets. In this study, we evaluated serum and tissue samples from a large cohort of ECD patients focusing on two major pro-fibrotic mediators, TGF-β1 and chemokine ligand 18 (CCL18). We found a marked increase in CCL18 but not TGF-β1 levels in serum and lesions of ECD patients (p < 0.001), independently of treatment status and consistently over time. Using a linear mathematical model, we also found that elevated CCL18 serum levels correlate with both number and severity of disease localizations. These findings suggest the involvement of CCL18-induced fibrosis in ECD pathogenesis, providing a rationale for exploring CCL18 inhibition as a treatment for progressive fibrosis in ECD.

FDG PET/CT Findings of Erdheim-Chester Disease: Radiologic Response to a Novel Treatment Regimen

Erdheim-Chester disease (ECD) is a rare form of non-Langerhans histiocytosis with deposition of lipid-laden macrophages in numerous organs. A 74-year-old man with a history of coronary artery disease, hypertension, and hyperlipidemia presented with nonspecific symptoms including back pain, nausea, vomiting, vertigo, and left leg pain. A neutrophil-predominant elevated WBC count and a bone biopsy revealing histiocytic proliferation positive for CD68 and CD163 and negative for S100 was noted. FDG PET/CT, MRA, and CTA images were obtained. We review the radiologic hallmarks of ECD and demonstrate the radiologic manifestations of response to combined BRAF and MEK inhibitor treatment.

Solving a Mystery . . . 8 Years Later

Erdheim-Chester disease is a rare non-Langerhans cell histiocytosis with multisystem involvement and insidious symptoms. In this article, we describe an interesting case of Erdheim-Chester disease that was eventually diagnosed 8 years after symptoms initially started.

Neuroradiologic manifestations of Erdheim-Chester disease

Background

We describe the neuroradiologic features of a cohort of patients with Erdheim-Chester disease.

Methods

We assessed patients at Mayo Clinic Rochester between January 1, 1990, and July 31, 2016, with pathologically confirmed Erdheim-Chester disease (n = 53).

Results

Neuroimaging, including head CT (n = 17), brain MRI (n = 39), orbital MRI (n = 15), and spine MRI (n = 16), was available for 42 participants. Median age at diagnosis was 55 years (interquartile range 46-66) with higher male prevalence (33:20). Neurologic symptoms were identified in 47% (25/53); BRAF^V600E mutation in 58% (15/26). Median follow-up was 2 years (range 0-20) with 18 patients deceased. Radiologic disease evidence was seen in dura (6/41), brainstem (9/39), cerebellum (8/39), spinal cord (2/16), spinal epidura (2/16), hypothalamic-pituitary axis (17/39), and orbits (13/42). T2 white matter abnormalities (Fazekas score ≥1) were present in 21/34 patients. Diabetes insipidus was present in 30% (16/53); 8 had abnormal hypothalamic-pituitary axis imaging. Radiographic evidence of CNS involvement (i.e., dural, brain, including Fazekas score >1, or spinal cord) occurred in 55% (22/40) and was unassociated with significantly increased mortality.

Conclusions

Erdheim-Chester disease commonly and variably involves the neuraxis. Patients with suspected Erdheim-Chester disease should undergo MRI brain and spine and screening investigations (serum sodium, serum and urine osmolality) for diabetes insipidus to clarify extent of neurologic disease.

A possible case of Erdheim-Chester Disease

Aim: To present the case of a 57-year-old male with progressive bilateral proptosis. Material and method: The patient presented with bilateral proptosis and strength deficiency on the upper limbs. During hospitalization, the progression was unfavorable; proptosis progressed, causing a severe loss of vision in the left eye (from 0.8 Snellen to NLP). Results: The imagistic investigation revealed bilateral infiltration of the orbits, infiltrative lesions to the mediastinum and the abdomen. The patient was referred to neurosurgery for further management. Surgical orbital decompression was performed with biopsy. The histopathological examination revealed non-Hodgkin small cell lymphoma. Conclusions: Assembling the clinical and paraclinical data we have suspected the possible diagnosis of Erdheim-Chester disease, however, positive diagnosis has not been achieved.

Erdheim-Chester Disease Involving Lymph Nodes and Liver Clinically Mimicking Lymphoma: A Case Report

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis and multisystem disease. First described in 1930, there are no more than 750 cases reported. The etiology remains unknown, but a majority of cases of ECD and Langerhans cell histiocytosis were found to have clonal mutations involving genes of the mitogen-activated protein kinase pathway. We recently encountered a 53-year-old male patient with extensive ECD involving the systemic lymph nodes, pleura, liver, and long bones clinically mimicking malignant lymphoma. Biopsies were performed at multiple sites, including a pleural mass, an external iliac lymph node, bone marrow, and the liver. Based on histopathological and immunohistochemical findings of positivity for CD68 and negativity for CD1a and S-100, the patient was diagnosed with ECD. Interferon-α was administered as the first-line treatment, but the patient rapidly progressed to hepatic failure after 2 months of treatment. We report this rare case of ECD clinically mimicking malignant lymphoma and diagnosed by careful pathological review.

Adult leukoencephalopathies with prominent infratentorial involvement can be caused by Erdheim-Chester disease

BACKGROUND

Leukoencephalopathies with prominent involvement of cerebellum and brainstem, henceforward called prominent infratentorial leukoencephalopathies (PILs), encompass a variety of inherited and acquired white matter diseases. Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis likely under-diagnosed as cause of adult PIL.

METHODS

We reviewed the clinical and laboratory information of ten consecutive sporadic adult patients with PIL of unknown origin, who were investigated for ECD.

RESULTS

There were seven males and three females; mean age at clinical onset was 49.6 years (range 38-59); cerebellar ataxia with or without other neurological symptoms was the only or the main clinical manifestation; diabetes insipidus was present in three individuals. Eight patients had white matter focal supratentorial abnormalities, in addition to the infratentorial white matter changes. Six out of eight patients had spinal cord lesions. Thoraco-abdominal CT showed periaortic sheathing in two patients, whole-body FDG-PET revealed increased glucose uptake in the long bones of the legs in five patients, brain FDG-PET showed overt infratentorial hypermetabolism in one patient. In eight patients, ECD was confirmed by bone scintigraphy, pathological data, or both. Two ECD patients treated with vemurafenib showed a marked improvement of neurological symptoms and brain MRI abnormalities at 1 year follow-up.

CONCLUSIONS

Symptoms of PIL can be the only clinical manifestation of ECD. Adult patients with PIL of unknown origin should undergo investigations aimed at unveiling ECD, including bone scintigraphy and whole-body FDG-PET. The early diagnosis allows starting disease-modifying therapies of an otherwise life-threatening disease.

CNS Erdheim-Chester Disease: A Challenge to Diagnose

Erdheim-Chester disease (ECD) is a rare nonLangerhans cell histiocytosis. Although approximately 50% of cases eventually involve the central nervous system (CNS), the CNS has seldom been reported as the initial biopsy site. The diagnosis of CNS ECD can be challenging due to morphologic overlap with reactive histiocytic proliferation, Langerhans cell histiocytosis (LCH), and extranodal Rosai-Dorfman disease (RDD). We present 3 cases from our files that illustrate the protean manifestations of ECD. Case 1 was a 47-year-old man with ataxia, dysarthria, and intermittent ophthalmoplegia whose cerebellar biopsy had shown only profuse, nonspecific Rosenthal fiber-rich piloid gliosis; ECD was diagnosed only at autopsy. The gliosis and marked variations in histiocyte morphology in different anatomical sites added to the diagnostic challenge. Case 2 was a 67-year-old female with chronic progressive symptoms and a pontine lesion that had been considered to be CLIPPERS by neuroimaging. Identification of a BRAFV600E mutation allowed an ECD diagnosis and treatment with the specific BRAFV600E inhibitor vemurafenib, which resulted in a marked sustained clinical response. Case 3 was diagnosed as ECD after positive bone biopsy with typical foamy histiocytes. Six years later, there was massive dural involvement that showed RDD-like, BRAF-mutation-negative histiocytosis. These cases highlight the clinical and histologic overlap that can occur among these disorders.

Intracranial Erdheim-Chester Disease Mimicking Parafalcine Meningioma: Report of Two Cases and Review of the Literature

BACKGROUND

Erdheim-Chester disease (ECD) is a rare, non-Langerhans cell histiocytosis that typically occurs in middle-aged patients. It is usually characterized by multifocal osteosclerotic lesions of the long-bones, however many cases have extraskeletal involvement. Central nervous system (CNS) involvement is common, but isolated CNS involvement at presentation has rarely been reported.

CASE DESCRIPTION

Here we report two cases of dural-based ECD mimicking meningioma on imaging with no other identified sites of disease.

CONCLUSION

ECD is a rare disease, with isolated CNS involvement reported only a few times in the literature. The significance of this presentation requires additional study and long-term follow up.

Vemurafenib (BRAF Inhibitor) Therapy for Orbital Erdheim-Chester Disease

Erdheim-Chester disease is a rare xanthogranulomatous systemic disease, which involves the orbit in some cases. Through this case report, the authors review the treatment modalities used in orbital Erdheim-Chester disease and explore a newer modality of treatment. Cases of orbital Erdheim-Chester disease were identified in the literature utilizing a PubMed search and all the treatment modalities were reviewed. The response to treatment of orbital Erdheim-Chester disease has been poor with the various medical and surgical treatment modalities used in the past. The authors report the use of BRAF inhibitor with a remarkable response in our case.

18F-FDG PET/CT in Erdheim-Chester Disease: Imaging Findings and Potential BRAF Mutation Biomarker

The purpose of this study was to evaluate ¹⁸F-FDG PET/CT for the diagnosis, management, and treatment of Erdheim-Chester disease (ECD). Methods: Our institutional database (2007-2017) was retrospectively reviewed for patients with pathologically proven ECD. A chart review yielded demographics, clinical information, and 5 categories of clinical impact. Two radiologists in consensus interpreted the images. Imaging findings were correlated with clinical data. Results: Seventy-one ¹⁸F-FDG PET/CT examinations were performed for 32 patients. The average SUV_max of the most active disease site was 9.2 (SD, 6.1). The most common sites involved were the skeleton (90.6% of patients, including 47% with axial and pelvic skeletal involvement), kidneys (81.3%), and central nervous system (CNS) (46.9%). Twenty-six patients were tested for a proto-oncogene B-Raf ^V600E (BRAF) mutation (18 had the mutation and 8 did not). The presence of a BRAF mutation was associated with ¹⁸F-FDG-avid CNS disease (P = 0.0357), higher SUV_max (P = 0.0044), and greater mortality (P = 0.0215). The presence of CNS disease had 88% specificity and a 92% positive predictive value for predicting the presence of a BRAF mutation. PET/CT examination results influenced patient management in 48% of cases (34/71). Conclusion:¹⁸F-FDG PET/CT results may act as a biomarker for the presence of a BRAF mutation, aid in establishing a diagnosis, guide biopsies, and gauge the treatment response in ECD patients. Axial and pelvic skeletal involvement is greater than previously reported.

Erdheim-Chester Disease with No Skeletal Bone Involvement and Massive Weight Loss

Erdheim-Chester disease (ECD) is a rare type of non-Langerhans cell histiocytosis, with only 550 cases reported worldwide. ECD is characterized by diffuse histiocytic infiltration of multiorgans. The age of presentation of this disease is typically between 40 and 70 years. Bone disease is the most common symptom, as unique radiological findings of long bone sclerosis occur in 96% of cases. Furthermore, BRAF V600E mutation is detected in 60% of ECD cases. In this manuscript, we are describing a unique case of ECD; the patient is younger than most reported cases and has no bone pain or any skeletal involvement. This patient has unintentionally lost about 50% of his body mass and is suffering from progressive cerebellar manifestations with radiological evidence of cerebellar atrophy, in contrast to the usual ECD manifestation of cerebellar infiltration. In addition, the patient has cardiac, retroperitoneal, and perinephric involvement, but he retains his sexual drive and fertility. A tissue biopsy from the retroperitoneal mass displayed typical morphological and immunohistochemical features of ECD, and BRAF V600E mutation was detected. He was treated with pegylated interferon alpha, but his disease progressed and the treatment was changed to vemurafenib to which he had an excellent response at 6 weeks.

Histiocytic neoplasms in the era of personalized genomic medicine

PURPOSE OF REVIEW

Since the discovery of B-Raf proto-oncogene (BRAF) V600E mutations in histiocytic neoplasms, diverse kinase alterations have been uncovered in BRAF V600E-wildtype histiocytoses. The purpose of this review is to outline recent molecular advances in histiocytic neoplasms and discuss their impact on the pathogenesis and treatment of these disorders.

RECENT FINDINGS

Activating kinase alterations discovered in BRAF V600E-wildtype Langerhans (LCH) and non-Langerhans cell histiocytoses (non-LCH) result in constitutive activation of the mitogen-activated protein kinase and/or phosphoinositide 3-kinases-Akt murine thymoma pathways. These kinase alterations include activating mutations in A-Raf proto-oncogene, mitogen-activated protein kinase kinase 1, neuroblastoma rat sarcoma viral oncogene homolog, Kirsten rat sarcoma viral oncogene homolog, and phosphatidylinositol-4,5-bisphosphate 3 kinase, catalytic subunit α kinases in LCH and non-LCH; BRAF, anaplastic lymphoma receptor tyrosine kinase, and neurotrophic tyrosine kinase, receptor type 1 fusions, as well as the Ets variant 3-nuclear receptor coactivator 2 fusion in non-LCH; and mutations in the mitogen-activated protein kinase kinase kinase 1 and Harvey rat sarcoma viral oncogene homolog kinases in LCH and histiocytic sarcoma, respectively. These discoveries have refined the understanding of the histiocytoses as clonal, myeloid neoplasms driven by constitutive mitogen-activated protein kinase signaling and identified molecular therapeutic targets with promising clinical responses to rapidly accelerated fibrosarcoma and mitogen-activated protein kinase kinase inhibition.

SUMMARY

Genomic analyses over the last 6 years have identified targetable kinase alterations in BRAF V600E-wildtype histiocytic neoplasms. However, despite this progress, the molecular pathogenesis and therapeutic responsiveness of non-BRAF V600E kinase alterations are still poorly defined in these disorders.

Erdheim-Chester disease: atypical presentation of a rare disease

We report the clinical case of an adult patient referred to our hospital because of trismus due to a tumour in the right infratemporal and pterygomaxillary fossa. He referred hyporexia, weight loss and right trigeminal neuralgia. On physical examination, he had trismus and diplopia. On neuroimaging, the tumour invaded the central nervous system affecting the right temporal lobe and orbit, and the sellar region. Tumour biopsy revealed foamy histiocytes and isolated giant multinuclear cells immunoreactive to CD68 and negative to CD1a and S100. A diagnosis of Erdheim-Chester disease was made. Non-evidence of large bone involvement was found in neither plain radiographs nor Technetium 99 m bone scintigraphy. BRAFV600E mutation analysis was negative. Because of raised intracranial pressure, a debulking surgery of the intracranial histiocytic process was performed. The patient improved his symptoms and remains clinically stable after 12 months of treatment with pegylated interferon-α-2a 180 µg/weekly.

A cytologic diagnosis of BRAFV600E Erdheim-Chester disease on pericardial fluid

We report the case of a 74-year-old woman admitted to the emergency unit for resting dyspnea. Clinical presentation, cardiac MRI and echocardiography were consistent with cardiac tamponade requiring emergency pericardiocentesis. Cytologic examination of the pericardial fluid revealed the presence of CD68^pos CD1a^neg S100^neg foamy histiocytes (Fig. 1). Additional investigations complied with the diagnosis of Erdheim-Chester histiocytosis. Treatment with αIFN was initiated but the patient developed severe neutropenia that contraindicated further administration. The detection of BRAF^V600E mutation on histiocytes isolated from the pericardial liquid and CNS involvement (cerebral masses) prompted the administration of vemurafenib, a selective BRAF^V600E kinase inhibitor. Four months after the initiation of low-dose vemurafenib, pericarditis almost resolved and cerebral masses decreased by 50% (Fig. 2). To our knowledge, analysis of pericardial fluid allowing the diagnosis of Erdheim-Chester disease and the detection of the BRAF^V600E mutation has in fact been rarely described in the literature. This case report and the successful evolution under vemurafenib also support the use of BRAF^V600E inhibitors in αIFN-intolerant patients with BRAF^V600E mutation, particularly in case of heart and central nervous system involvement.

Clinical and Radiologic Responses to Cladribine for the Treatment of Erdheim-Chester Disease

Importance

While cladribine is best known for the treatment of hairy cell leukemia and other lymphoid cancers, it also has activity against myeloid neoplasms, such as Erdheim-Chester disease (ECD).

Objective

To assess the efficacy of cladribine (2-chloro-2'-deoxyadenosine) in the treatment of ECD.

Design, Setting, and Participants

This study was a single-institution retrospective medical record review from January 1, 1998, to April 6, 2016, at a tertiary academic medical center. In all eligible cases, the diagnosis of ECD was made using clinical criteria in conjunction with histopathologic findings.

Exposure

Cladribine therapy in first-line treatment or later.

Main Outcomes and Measures

Two response criteria were used, clinical and radiological. For clinical response, the following criteria were used: complete response (complete resolution of symptoms attributed to ECD), partial response (partial resolution of symptoms attributed to ECD), stable disease (no change in symptoms attributed to ECD), and progressive disease (worsening of symptoms attributed to ECD). For radiological response, the following categories were used: complete response (complete resolution of proven or suspected lesion due to ECD), partial response (partial resolution of proven or suspected lesion due to ECD), stable disease (no significant change in proven or suspected lesion due to ECD for ≥3 months), and progressive disease (progression or worsening of proven or suspected lesion due to ECD).

Results

A total of 63 adult patients with confirmed ECD were identified. Their median age at diagnosis of ECD was 54 years (age range, 18-80 years), and 67% (42 of 63) were male. Cladribine was the most commonly used chemotherapeutic agent and was administered in 21 of 63 patients (33%). Their median age at the time of cladribine therapy was 62 years (age range, 40-78 years). Cladribine was used as the first-line treatment in 9 patients and as later-line treatment in the remaining 12 patients. The median number of cycles of cladribine administered was 2.5 (range, 1-6). The overall clinical response rate was 52% (9 of 17) (6% [1 of 17] complete response and 46% [8 of 17] partial response), with 18% (3 of 17) stable disease and 30% (5 of 17) progressive disease. Among patients who responded to cladribine therapy, the median duration of clinical response was 9 months (range, 6-129 months), with ongoing response in 2 patients. The overall radiological response rate was 54% (8 of 15) (all partial response), with 26% (4 of 15) stable disease and 20% (2 of 15) progressive disease. Treatment-related adverse effects included 2 infectious complications (pneumonia and central line infection, both requiring hospitalization) and 2 hematologic adverse effects (grade 4 neutropenia and thrombocytopenia, and grade 3 neutropenia, both requiring therapy discontinuation).

Conclusions and Relevance

Cladribine has moderate clinical efficacy in the treatment of ECD and can be considered a treatment option in cases without the BRAF V600E mutation. It is generally well tolerated and may result in a durable response.

A rare case of CD1a-negative Langerhans cell histiocytosis of the central nervous system in a child

Langerhans cell histiocytosis is a dendritic cell disorder with a wide spectrum of severity and presentations. Histopathology typically demonstrates a proliferation of Langerhans cells and a lymphohistiocytic inflammatory infiltrate with eosinophils. The diagnosis is supported by immunohistochemistry with the cell markers S100, CD1a, CD68, and Langerin [Blood, 126, 2015, 26 and N Engl J Med, 331, 1994, 154].

Successful Lung Transplantation for Pulmonary Disease Associated With Erdheim-Chester Disease

A 53-year-old man with pulmonary fibrosis associated with Erdheim-Chester disease achieved long-term survival after lung transplantation. Major clinical manifestations included lung and bone injuries, and other vital organs were functionally unaffected by the disease. After a careful observation for the disease progression, he underwent bilateral deceased-donor lung transplantation. He has returned to his normal social life and is doing well without recurrence of Erdheim-Chester disease in the lung allograft or progression in other organs 5 years after transplant. Lung transplantation is a potentially reasonable treatment option for Erdheim-Chester disease involving the lungs if the functions of other vital organs remain stable.