Advances in Understanding and Management of Erdheim-Chester Disease.

Erdheim Chester Disease (ECD) is a rare histiocytic disorder marked by infiltration of organs with CD68+ histiocytes. ECD stems from mutations of BRAF and MAP2K1 in hematopoietic stem and progenitor cells (HSPCs), which further differentiate into monocytes and histiocytes. Histopathology reveals lipid-containing histiocytes, which test positive for CD68 and CD133 in immunohistochemistry. Signs and symptoms vary and depend on the organ/s of manifestation. Definitive radiological results associated with ECD include hairy kidney, coated aorta, and cardiac pseudotumor. Treatment options primarily include anti-cytokine therapy and inhibitors of BRAF and MEK signaling.

Effect of Liposome-Encapsulated Dextrazide on Local Regulation of Extracellular Matrix Metabolism in Liver and Lungs of Mice with during Chronic BCG-Induced Granulomatosis.

The liposomal form of isonicotinic acid hydrazide conjugate with oxidized dextran (liposomeencapsulated dextrazide, LEDZ) injected intraperitoneally for 3 months to BALB/c mice with chronic BCG-induced granulomatosis (6 month after infection) down-regulated activities of protease (MMP) and antiprotease (TIMP-1, TIMP-2, α2-macroglobulin) components of the regulation system, which indicates a drop of destructive and inflammatory potential of BCGinduced granulomatosis. The persistent enhanced hyaluronidase activity in the liver and its reduced (normalized to control level) activity in the lungs after administration of LEDZ indicates a greater hydrolysis of hyaluronan in the liver than in the lungs. LEDZ-induced changes in MMP/TIMP system in mouse liver and lungs are characterized with relative elevation of protease activity over that of antiprotease one.

A case of suprasellar Erdheim-Chester disease and characterization of macrophage phenotype.

Erdheim-Chester disease (ECD) is a non-Langerhans form of histiocytosis that occurs in systemic organs, such as bone, the central nervous system, cardiovascular system, lungs, and kidneys. We report the case of a 68-year-old woman with a cranial pharyngeal tumor and a bone lesion in the tibia. The case was diagnosed as ECD. Pathological analysis showed the typical feature of foamy macrophage accumulation. The macrophages were positive for CD68, and negative for CD1a and S100. The BRAF V600E mutation was identified. In addition, immunohistochemistry was performed for the detailed characterization of the macrophages. The macrophages had low proliferative activity and an M2-like phenotype, and they expressed colony-stimulating factor-1 receptor (CSF1R) on the cell surface.

Metabolic Resolution of Lytic Lesions in Erdheim-Chester Disease on 18F-FDG PET/CT.

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytic disorder with variable clinical presentation most commonly involving the skeletal system. The long bones are the most common site of involvement giving a characteristic bone scintigraphy pattern of increased bilateral symmetric uptake in metadiaphyseal regions. We describe the findings of serial F-FDG PET/CT in a 16-year-old adolescent girl with ECD, emphasizing the role of F-FDG PET/CT in response assessment of ECD.

Erdheim-Chester disease: An in vivo human model of Mϕ activation at the crossroad between chronic inflammation and cancer.

Erdheim-Chester disease (ECD) is a rare histiocytosis characterized by infiltration of multiple tissues by CD68+ foamy Mϕs (or 'histiocytes'). Clinical manifestations arise from mass-forming lesions or from tissue and systemic inflammation. ECD histiocytes harbor oncogenic mutations along the MAPK-kinase signaling pathway (BRAFV600E in more than half of the patients), and secrete abundant pro-inflammatory cytokines and chemokines. Based on these features, ECD is considered an inflammatory myeloid neoplasm, and is accordingly managed with targeted kinase inhibitors or immunosuppressive and cytokine-blocking agents. Evidence is emerging that maladaptive metabolic changes, particularly up-regulated glycolysis, represent an additional, mutation-driven feature of ECD histiocytes, which sustains deregulated and protracted pro-inflammatory activation and cytokine production. Besides translational relevance to the management of ECD patients and to the development of new therapeutic approaches, recognition of ECD as a natural human model of chronic, maladaptive Mϕ activation instructs the understanding of Mϕ dysfunction in other chronic inflammatory conditions.

Juvenile xanthogranuloma: A herald to the diagnosis of Erdheim-Chester disease in an adult with acute leukemia.

A 21-year-old man with B-cell acute lymphoblastic leukemia developed an eruption of multiple flesh-colored nodules and persistent fevers. A lesional biopsy showed diffuse dermal infiltrates of histiocytes, foam cells, and Touton giant cells consistent with juvenile xanthogranulomatosis. Upon further investigation, the patient's constellation of findings fit criteria for Erdheim-Chester disease.

Erdheim-Chester disease with orbital involvement: Case report and ophthalmic literature review.

Erdheim-Chester disease (ECD) is a rare xanthogranulomatous disease in which orbital involvement can have devastating outcomes. Through a case report and review of the ophthalmic literature, we explore orbital findings, disease progression, and treatment options. Cases of orbital involvement in Erdheim-Chester disease were identified in the ophthalmic literature with a PubMed query and review of cited references. A total of 14 publications reporting 19 separate cases that included ophthalmic examination data were identified. Patient ages ranged from 26-77 years with a mean age of 50 years. Seventy-four percent (14/19) were men. Vision progression to no light perception was found in 32% (6/19) of the patients. Reviewed cases reported a variety of medical and surgical treatment approaches, however, only 53% reported cases (10/19) demonstrated disease improvement or stabilization. Erdheim-Chester disease with orbital involvement is a devastating disease with a poor prognosis. Awareness of this entity by the ophthalmologist is important as orbital signs and symptoms may manifest early, and orbital biopsy is often crucial to the definitive diagnosis.

Endocrine Manifestations in a Monocentric Cohort of 64 Patients With Erdheim-Chester Disease.

CONTEXT: Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis, characterized by infiltration of foamy histiocytes in multiple organs. Endocrine involvement has mostly been described in case reports. OBJECTIVE: We performed systematic endocrine evaluation in a large cohort of patients with ECD. DESIGN: This was a single-center observational study conducted between October 2007 and May 2013. SETTING: The evaluation was conducted in Pitié-Salpêtrière Hospital (Paris, France), a tertiary care hospital. PATIENTS: Sixty-four consecutive patients with ECD (sex ratio, 3.6; mean age, 57.6 years [range, 20-80 years]). Thirty-six patients had follow-up assessments. INTERVENTIONS: There were no interventions. MAIN OUTCOME MEASURES: Clinical, biological, and morphological evaluations of pituitary, gonadal, adrenal, and thyroid functions, as well as metabolic evaluation, were performed. RESULTS: Diabetes insipidus was found in 33.3% of patients, frequently as the first manifestation of ECD. Anterior pituitary dysfunction was found in 91.3% of patients with full anterior pituitary evaluation, including somatotropic deficiency (78.6%), hyperprolactinemia (44.1%), gonadotropic deficiency (22.2%), thyrotropic deficiency (9.5%), and corticotropic deficiency (3.1%). Thirty-five patients (54.7%) had ≥2 anterior pituitary dysfunctional axes, rising to 69.6% (16 of 23) when only patients with complete evaluations were considered. Two patients had panhypopituitarism. Infiltration of the pituitary and stalk was found with magnetic resonance imaging in 24.4% of patients. Testicular insufficiency was found in 53.1% of patients, with sonographic testicular infiltration in 29% of men, mostly bilateral. Computed tomography adrenal infiltration was found in 39.1% of patients, and 1 case of adrenal insufficiency was observed. No patient was free of endocrine hormonal or morphological involvement. Endocrine dysfunctions were most often permanent, and new deficits appeared during follow-up. CONCLUSION: Endocrine involvement is very frequent in ECD and should be evaluated carefully at diagnosis and during follow-up.

Langerhans cell histiocytosis and Erdheim-Chester disease, both with cutaneous presentations, and papillary thyroid carcinoma all harboring the BRAF(V600E) mutation.

Langerhans cell histocytosis (LCH) and Erdheim-Chester disease are two rare histiocytic disorders. Their occurrence in the same patient is more infrequent, but has been described. We report a case of a 38-year-old woman who presented with a diagnosis of single system cutaneous LCH. Subsequently, she developed multiple papules on her extremities consistent with a non-LCH xanthogranuloma type lesion. BRAF(V600E) mutation immunostain, VE1 was positive in the skin lesion, which was confirmed by molecular polymerase chain reaction (PCR) studies, initiating a complete systemic workup for Erdheim-Chester disease. Systemic involvement was confirmed with bilateral sclerotic bone lesions and retroperitoneal and pelvic fibrosing disease. She was also found to have a BRAF(V600E) mutation positive papillary thyroid carcinoma. New suspicious cutaneous lesions presenting in patients with a history of LCH need to be biopsied. A BRAF(V600E) mutation in a non-LCH histiocytic lesion with a xanthogranuloma phenotype (CD163/CD68/CD14/fascin/Factor 13a) should prompt an Erdheim-Chester disease workup. This is a unique case of a woman with BRAF(V600E) mutation positive Erdheim-Chester disease and cutaneous LCH, while also being, to our knowledge, the first reported case in the English literature of it occurring in a patient with a BRAF(V600E) mutation positive papillary thyroid carcinoma.

Disseminated histiocytoses biomarkers beyond BRAFV600E: frequent expression of PD-L1.

The histiocytoses are rare tumors characterized by the primary accumulation and tissue infiltration of histiocytes and dendritic cells. Identification of the activating BRAFV600E mutation in Erdheim-Chester disease (ECD) and Langerhans cell histiocytosis (LCH) cases provided the basis for the treatment with BRAF and/or MEK inhibitors, but additional treatment options are needed. Twenty-four cases of neoplastic histiocytic diseases [11 extrapulmonary LCH, 4 ECD, 4 extranodal Rosai-Dorfman disease (RDD), 3 follicular dendritic cell sarcoma (FDCS), 1 histiocytic sarcoma (HS) and 1 blastic plasmacytoid dendritic cell neoplasm (BPDCN)] were analyzed using immunohistochemical and mutational analysis in search of biomarkers for targeted therapy. BRAF V600E mutations were detected in 4/11 LCH and 4/4 ECD cases. A pathogenic PTEN gene mutation and loss of PTEN protein expression were identified in the case of HS. Increased expression of PD-L1 (≥2+/≥5%) was seen in 3/4 ECD, 7/8 LCH, 3/3 FDCS and 1/1 HS, with overall 81% concordance between 2 antibodies used in the study (SP142 vs. MAB1561 clone). These results show for the first time significant expression of the PD-L1 immune checkpoint protein in these disorders, which may provide rationale for addition of immune check-point inhibitors in treatment of disseminated and/or refractory histiocytoses.

Reproducible and sustained efficacy of targeted therapy with vemurafenib in patients with BRAF(V600E)-mutated Erdheim-Chester disease.

PURPOSE: Histiocytoses are rare disorders with heterogeneous prognosis. BRAF(V600E) mutations have been observed in half of patients with Langerhans cell histiocytosis (LCH) and in 50% to 100% of patients with Erdheim-Chester disease (ECD) patients. We recently reported short-term efficacy of a BRAF inhibitor (vemurafenib) in three patients with multisystemic ECD. PATIENTS AND METHODS: Vemurafenib was given to eight patients with multisystemic ECD with CNS and/or cardiac involvement. All patients were refractory to first-line treatment and harbored a BRAF(V600E) mutation. Four patients also had LCH lesions. Positron emission tomography (PET) scan response at month 6 was used as the main evaluation criterion. Secondary evaluation criteria were comparison at baseline and at last visit of PET and of cardiovascular and cerebral infiltrations (computed tomography scan and magnetic resonance imaging [MRI]). RESULTS: All patients were partial metabolic responders at 6 months of vemurafenib, and the median reduction in maximum standardized uptake value was 63.5% (range, 41.3% to 86.9%). Evaluation of cardiac and aortic infiltrations showed that seven patients had a partial response and one patient had stable disease according to surface measurements derived from RECIST criteria. The four patients with infratentorial CNS infiltration had an objective decrease of the lesions on MRI. All patients had an improvement of general symptoms and a persistent response to vemurafenib, with a median follow-up time of 10.5 months (range, 6 to 16 months). Skin adverse effects were frequent and severe. CONCLUSION: Vemurafenib has an objective and sustained efficacy in BRAF(V600E)-mutated ECD as second-line therapy. In contrast to melanoma, no resistance has emerged to date after 6 to 16 months.

Mutually exclusive recurrent somatic mutations in MAP2K1 and BRAF support a central role for ERK activation in LCH pathogenesis.

Langerhans cell histiocytosis (LCH) is a myeloproliferative disorder characterized by lesions composed of pathological CD207(+) dendritic cells with an inflammatory infiltrate. BRAFV600E remains the only recurrent mutation reported in LCH. In order to evaluate the spectrum of somatic mutations in LCH, whole exome sequencing was performed on matched LCH and normal tissue samples obtained from 41 patients. Lesions from other histiocytic disorders, juvenile xanthogranuloma, Erdheim-Chester disease, and Rosai-Dorfman disease were also evaluated. All of the lesions from histiocytic disorders were characterized by an extremely low overall rate of somatic mutations. Notably, 33% (7/21) of LCH cases with wild-type BRAF and none (0/20) with BRAFV600E harbored somatic mutations in MAP2K1 (6 in-frame deletions and 1 missense mutation) that induced extracellular signal-regulated kinase (ERK) phosphorylation in vitro. Single cases of somatic mutations of the mitogen-activated protein kinase (MAPK) pathway genes ARAF and ERBB3 were also detected. The ability of MAPK pathway inhibitors to suppress MAPK kinase and ERK phosphorylation in cell culture and primary tumor models was dependent on the specific LCH mutation. The findings of this study support a model in which ERK activation is a universal end point in LCH arising from pathological activation of upstream signaling proteins.

Recurrent RAS and PIK3CA mutations in Erdheim-Chester disease.

Erdheim-Chester disease (ECD) is a rare histiocytic disorder that is challenging to diagnose and treat. We performed molecular analysis of BRAF in the largest cohort of ECD patients studied to date followed by N/KRAS, PIK3CA, and AKT1 mutational analysis in BRAF wild-type patients. Forty-six of 80 (57.5%) of patients were BRAFV600E-mutant. NRAS mutations were detected in 3 of 17 ECD BRAFV600E wild-type patients. PIK3CA mutations (p.E542K, p.E545K, p.A1046T, and p.H1047R) were detected in 7 of 55 patients, 4 of whom also had BRAF mutations. Mutant NRAS was present in peripheral blood CD14(+) cells, but not lymphoid cells, from an NRASQ61R mutant patient. Our results underscore the central role of RAS-RAF-MEK-ERK activation in ECD and identify an important role of activation of RAS-PI3K-AKT signaling in ECD. These results provide a rationale for targeting mutant RAS or PI3K/AKT/mTOR signaling in the subset of ECD patients with NRAS or PIK3CA mutations.