Xanthomatous hypophysitis

High Prevalence of Vulvar and Hepatic Manifestations in a Series of 18 Histiocytosis with Brafdel Mutations

Association of both Langerhans cell histiocytosis and Erdheim-Chester disease linked to the BRAFV600E mutation

BACKGROUND Histiocytic neoplasms are clonal hematopoietic disorders of myeloid lineage. Involvement of neurologic structures by histiocytic infiltration or disease-associated neurodegeneration (ND) represents a severe disease phenotype associated with morbidity and mortality. Despite recent advances with BRAF and MEK inhibitors, patients with neurohistiocytic involvement continue to demonstrate suboptimal outcomes. Intra-arterial chemotherapy (IAC) may represent an effective therapy for this disease manifestation. METHODS Patients with biopsy-proven histiocytic neoplasms involving neurologic, ocular, or head and neck structures were treated with intra-arterial melphalan delivered via selective catheterization of tumor arterial vasculature. Patients treated had refractory/persistent tumorous disease or progressive functional decline despite BRAF/MEK inhibition, or had limited disease appropriate for local therapy. Patients were evaluated for radiologic (PET or CT/MRI) response and functional neurologic response with quantified ataxia and dysarthria scales, or change in visual acuity (VA), as appropriate. Procedure-related adverse events as well as clinical and laboratory toxicities were captured. RESULTS 74 IAC treatments were administered to 17 patients, 12 with tumorous disease (6 Rosai-Dorfman disease; 3 xanthogranuloma; 3 Langerhans cell histiocytosis[LCH]; 1 Erdheim-Chester disease [ECD]), 5 with ND-LCH/ECD, and ten with disease-related impairment of VA. Patients received a range of 2-12 IAC doses. 9/12 (75%) patients with tumorous disease had complete or partial radiologic response. 4/5 patients with ND had measurable improvement in dysarthria and 2/5 had measurable improvement in ataxia. 4/10 patients had improved VA. Of all patients with clinical or radiologic response, three have experienced disease recurrence since IAC in long-term follow-up. No procedural adverse events were observed, 1 patient had neutropenia and 1 patient melphalan hypersensitivity. CONCLUSIONS IA melphalan is a safe and robustly effective treatment option for tumorous and ND histiocytic neoplasms of neurologic, ocular, and head and neck structures.

BackgroundDiagnosis of Erdheim-Chester disease (ECD) is based on characteristic imaging of bone, retroperitoneal and/or cardiovascular involvement.1 Biopsy is mandatory to exclude other diagnoses and confirm infiltration of histiocytes, but histology...

Langerhans cell histiocytosis (LCH), juvenile xanthogranuloma (JXG), and Erdheim-Chester disease (ECD) represent histiocytic disorders with a wide range of clinical manifestations. Until recently, mechanisms of pathogenesis have been speculative and debate has focused on classification of these conditions as reactive versus neoplastic. Genomic studies have been challenged by scarce tissue specimens, as well as heterogeneous nature of the lesions with variable infiltration of pathologic histiocytes. Whole-exome sequencing recently revealed a very low frequency of somatic mutations in LCH, JXG, and ECD compared to other neoplastic disorders. However, at least in the cases of LCH and ECD, there is a very high frequency of activating mutations in MAPK pathway genes, most notably BRAF-V600E, as well as MAP2K1, in LCH and NRAS in ECD. In ECD, recurrent mutations in the PI3K pathway gene PIK3CA have also been described. The heterogeneous clinical manifestations of these disorders may therefore be the cumulative result of activation of MAPK mutations (along with modifying signals from other pathways) at distinct stages of myeloid differentiation. Implications of this model include redefinition of LCH, JXG, and ECD as a group of clinically diverse myeloid neoplastic disorders with a common mechanism of pathogenesis. This model supports refocusing therapeutic strategies for these diseases on a personalized approach based on specific mutations and the cell(s) of origin.

La maladie d’Erdheim-Chester, une néoplasie myéloïde inflammatoire

Histiocytosis is a syndrome characterized by fever, pain, and other symptoms caused by the neoplastic proliferation of atypical cells of the macrophage-dendritic cell lineage and surrounding inflammatory cell infiltration. The diagnosis is confirmed by the immune-histological features of biopsied specimens. From this viewpoint, histiocytosis is divided into Langerhans cell histiocytosis (LCH) (CD1a+/CD207+/CD14±/CD68±) and non-LCH, including Erdheim-Chester disease (ECD), juvenile xanthogranuloma, and Rosai-Dorfman disease (CD1a-/CD207-/CD14++/CD68++). Genetic alterations occur at the cellular level in hematopoietic progenitor cells, and environmental factors are assumed to influence tumor development. The genomic analysis of the lesions involved revealed driver mutations primarily in the MAPK pathway, including BRAF-V600E, and the PI3K pathway. This strongly suggests that abnormalities in these signaling pathways play a role in pathogenesis. Steroids, vinca alkaloids, cytarabine, and cladribine are commonly used to treat histiocytosis. However, efficacy has not been fully confirmed in any of them. In recent years, the efficacy of BRAF inhibitors and MEK inhibitors has been reported mainly in therapy-resistant and refractory cases of LCH and ECD.

Objective: To investigate the clinicopathological characteristics, histogenesis, immunophenotypes and molecular genetic features of primary intraosseous Rosai-Dorfman disease (RDD) for improving diagnostic accuracy and differential diagnosis. Methods: This retrospective study included 14 RDD cases diagnosed from January 2009 to January 2019 at Beijing Jishuitan Hospital, China. The immunohistochemical staining for S-100, cyclin D1, CD1a and CD207 expression was analyzed. The BRAF V600E and KRAS mutation analyses were performed using the Scorpions amplification refractory mutation system (ARMS) fluorescence quantitative PCR. Results: There were 6 female and 8 male patients, aged from 2 to 64 years (mean 31.4 years). All of the 14 cases occurred in the bone without lymph node disease, while one patient developed additional lesions within vertebra and nasal cavity. Radiographically, the lesions were lytic with sclerotic margins. Histologically, the lesions percolated through the medullary cavity in an infiltrative fashion and alternating hyper- and hypo-cellular regions of histiocytic clusters (seen as alternating dark and light zones at low magnification). Large histiocytes also showed emperipolesis. Some cases had areas of fibrosis and dense lymphoplasmacytic infiltrates. There were vasculitis and an increased number of plasma cells in the cases involving multiple sites. One case showed concurrence of RDD and Langerhans cell histiocytosis(LCH) with inconspicuous increase of Langerhans histiocytes. Immunohistochemical staining showed that the large histiocytes were positive for S-100, CD68 and CD163 in all cases. The nuclear immunoreactivity for cyclin D1 was observed in 13 of the 14 cases. S-100, CD1a and CD207 were positive in the case with concurrence of RDD and LCH. ARMS-PCR results showed that BRAF V600E mutation was observed in the cases with concurrence of RDD and LCH, while there were no KRAS mutations (7/7). Follow-up information was available for 12 patients and ranged from 9 to 49 months. Three of the 12 patients experienced recurrences after the first surgery. Conclusions: Primary intraosseous RDD is rare, and its concurrence with LCH is a very rare phenomenon. Its clinical symptoms, imaging, and pathological manifestations need to be distinguished from other bone lesions. The molecular detection of BRAF V600E and the nuclear expression of cyclin D1 mutations can be used for the diagnosis and differential diagnosis of RDD.

Myeloid Progenitors Define Extent of Disease in Mouse Models of Histiocytic Disorders: BRAFV600E Expression in Monocyte Lineage Recapitulates Erdheim-Chester Phenotype

Erdheim-Chester disease (ECD) is a rare form of non-Langerhans cell histiocytosis that typically affects many organs, including the lung and pleura. However, there are few studies concerning pulmonary involvement in ECD patients, as well as the difference of pulmonary involvement between ECD and Langerhans cell histiocytosis (LCH). We performed a retrospective study of 54 ECD patients, and compared the pulmonary manifestations with those of adult LCH patients in our centre. The median age of diagnosis of the 54 ECD patients was 48years (range 9-66years). Chest computed tomography (CT) scans revealed lung involvement in 49 (91%) patients and pleural involvement in 34 (63%). Thirty-three (61%) patients had interstitial lung disease (ILD) with varying degrees of interlobular septal thickening, micronodules, and ground-glass opacities. ECD and LCH patients with pulmonary involvement showed significant differences in smoking status (P<0·001), respiratory symptoms (P=0·001) such as cough and pneumothorax (P<0·001), and radiological findings, including cysts (P<0·001), opacities (P<0·001), and pleural thickening (P<0·001). With a median follow-up duration of 24months (range, 1-84months), the estimated three-year overall survival (OS) of this entire ECD cohort was 90·2%. Patients with ILD tended to have worse progression-free survival (PFS) than those with no ILD (P=0·29).

A 37-year-old right-handed woman sought care for a dull headache present for 6 months, which was followed by the development of radicular pain in the left leg radiating down the back of her leg into her foot, with associated left foot numbness. Magnetic resonance imaging of the lumbar spine showed an enhancing lesion within the conus. She was referred for neurosurgical evaluation and underwent magnetic resonance imaging of the entire neuraxis, which showed an enhancing lesion in the left cerebellum. She underwent a left cerebellar debulking surgical procedure. Postoperative diplopia developed for approximately 1 month and then subsequently resolved. She walked with a walker after surgery, with progressive deterioration in gait. Two months after surgery a postural tremor developed in the left arm and leg. She was referred for neurologic evaluation. Pathologic evaluation of cerebellar tissue showed foamy histiocytes and xanthomatous cells that stained positive for CD68 (KP1). Staining for CD1a was negative. Tissue immunohistochemistry for the BRAF V600E sequence variation was negative. No hyponatremia was detected. Positron emission tomography/computed tomography of the body from vertex to toes indicated hypermetabolism in the distal femur and proximal tibia. Examination and imaging findings were consistent with a diagnosis of multifocal Erdheim-Chester disease. The patient was initially treated with pegylated interferon, with clinical and radiographic progression. She was subsequently treated with vemurafenib and dexamethasone, with continued radiologic progression. Treatment with radiotherapy and cladribine were also unsuccessful. At that point, next-generation sequencing of cerebellar tissue showed a BRAF V471F sequence variation. She was then treated with trametinib, which resulted in a decrease in size of the cerebellar lesion and growth stabilization of the conus lesion. Histiocytic neoplasms are a heterogeneous group of multisystem disorders, primarily including Erdheim-Chester disease, Langerhans cell histiocytosis, and Rosai-Dorfman disease. Although initially thought to represent inflammatory processes, recent insights into their genomic architecture have shown that they are derived from macrophage-lineage neoplasms.

An 8-year-old boy presented with a history of holocranial headache for 4 weeks which was mild to moderate in intensity. There was history of intermittent vomiting for the same duration. The patient was drowsy for the last 10 days. Non-contrast CT scan of head showed a space-occupying lesion in lateral ventricles with hydrocephalus. MRI showed a large lobulated well-defined heterogeneous mass lesion filling up both lateral ventricles at the posterior and temporal horns, bilaterally reaching up to the level of the foramen magnum. The mass lesion was hypointense on T2-weighted images (T2W) and isointense to grey mater on T1W images. On contrast images there was intense homogeneous enhancement seen at the lesion (Fig. 1). Right fronto-temporo-parietal craniotomy with decompression of the tumor was performed. Perioperatively, the tumor was yellowish in color, firm, not able to be aspirated and minimally vascular. Clinical diagnosis of choroid plexus tumor was considered.

Highlights of the Management of Adult Histiocytic Disorders: Langerhans Cell Histiocytosis, Erdheim-Chester Disease, Rosai-Dorfman Disease, and Hemophagocytic Lymphohistiocytosis

Primary histiocytic tumors of the CNS are rare. The current WHO classification (2016) included 5 entities: Langerhans cell histiocytosis (LCH), Erdheim-Chester disease (ECD), Rosai-Dorfman disease (RDD), juvenile xanthogranuloma (JXG), and histiocytic sarcoma (HS) (1). The diagnosis usually is made based on the tumor differentiation as to the counterpart in normal histiocyte development. This article is protected by copyright. All rights reserved.

Langerhans cell histiocytosis (LCH) is a clonally derived neoplasm with a highly variable clinical course. Although LCH was once considered a disorder of immune regulation, the identification of activating mutations in the proto-oncogene BRAF-V600E in ~50%-60% of cases and MEK and ERK phosphorylation in 100% of examined cases, has changed the definition of LCH to a dendritic cell neoplasm with a strong inflammatory component. Current international LCH trials are focused on further improving the outcome of high-risk multisystem LCH patients, by decreasing the reactivation rate, optimizing early salvage regimens, and preventing late sequelae. Anecdotal responses to vemurafenib, a BRAF-V600E inhibitor, have been reported in a few cases of LCH and Erdheim-Chester disease. However, the development of resistance, as well as the potential risks of cutaneous and pancreatic cancers in patients with BRAF-V600E-mutated melanoma treated with single inhibitors, suggest the need for prospective trials with BRAF inhibitors, alone or in combination with other inhibitors of this pathway, for patients with refractory or multiply-relapsed LCH. The recent discovery of somatic mutations in ARAF and in MAP2K1, which lead to activation of the RAS-RAF-MEK -ERK pathway in the setting of wild-type BRAF, as well as the finding that activating mutation in MAP2K1 are relatively insensitive to MEK inhibitors, suggest that a more detailed understanding of this pathway in LCH may be necessary for the development of more effective targeted therapies.