Revised classification of histiocytoses and neoplasms of the macrophage-dendritic cell lineages. Blood. 2016;127:2672-2681. [PMID: 26966089 DOI: 10.1182/blood-2016-01-690636]

Comparison of neuroimaging features of histiocytic neoplasms with central nervous system involvement: a retrospective study of 121 adult patients

OBJECTIVES

To compare neuroimaging characteristics of three types of histiocytoses, namely Langerhans cell histiocytosis (LCH), Erdheim-Chester disease (ECD), and Rosai-Dorfman disease (RDD), with central nervous system (CNS) involvement.

METHODS

A total of 121 adult patients with histiocytoses (77 LCH, 37 ECD, and 7 RDD) and CNS involvement were retrospectively included. Histiocytoses were diagnosed based on histopathological findings combined with suggestive clinical and imaging features. Brain and dedicated pituitary MRIs were systematically analyzed for tumorous, vascular, degenerative lesions, sinus, and orbital involvement and for hypothalamic pituitary axis involvement.

RESULTS

Endocrine disorders, including diabetes insipidus and central hypogonadism, were more common in LCH patients than in ECD and RDD patients (p < 0.001). In LCH, tumorous lesions were mostly solitary (85.7%), located in the hypothalamic pituitary region (92.9%), and without peritumoral edema (92.9%), while in ECD and RDD, tumorous lesions were often multiple (ECD: 81.3%, RDD: 85.7%), their distribution was more widespread with meninges mostly involved (ECD: 75%, RDD: 71.4%), and they most likely presented with peritumoral edema (ECD: 50%, RDD: 57.1%; all p ≤ 0.020). Vascular involvement was an exclusive imaging characteristic of ECD (17.2%), which was not observed in LCH or RDD; this was also associated with a higher risk of death (p = 0.013, hazard ratio = 11.09).

CONCLUSION

The typical characteristic of adult CNS-LCH was endocrine disorders with radiological findings limited to the hypothalamic pituitary axis. The pattern of multiple tumorous lesions with predominant involvement of meninges was the main manifestation of CNS-ECD and CNS-RDD, while vascular involvement was pathognomonic for ECD and associated with poor prognosis.

CLINICAL RELEVANCE STATEMENT

Involvement of the hypothalamic-pituitary axis is the typical imaging characteristic of Langerhans cell histiocytosis. Multiple tumorous lesions, predominantly involving but not limited to meninges, occur in most Erdheim-Chester disease and Rosai-Dorfman disease patients. Vascular involvement occurs only in Erdheim-Chester disease patients.

KEY POINTS

• The different distribution patterns of brain tumorous lesions can help differentiate among LCH, ECD, and RDD. • Vascular involvement was an exclusive imaging finding of ECD and was associated with high mortality. • Some cases with atypical imaging manifestations were reported to further expand the knowledge on these diseases.

Therapie des nekrobiotischen Xanthogranuloms - Fallserie und aktuelle Literatur: Therapy of necrobiotic xanthogranuloma - case series and review of the literature

Das nekrobiotische Xanthogranulom ist eine seltene Erkrankung, die zu den Nicht‐Langerhans‐Zell‐Histiozytosen gehört. Charakteristisch sind gelbliche Hautveränderungen, die typischerweise periorbital lokalisiert sind. Extrakutane Manifestationen aller Organe sind möglich und können potenziell lebensbedrohliche Komplikationen verursachen. Die Erkrankung gehört zu den fakultativen Paraneoplasien und zeigt eine hohe Assoziation zu Paraproteinämien. Diese Aspekte sollten in der Umfelddiagnostik berücksichtigt werden. Da die Erkrankung sehr selten ist, gibt es bislang keine standardisierten Richtlinien zur Therapie. Als erfolgreiche Therapieregime haben sich insbesondere die Kombination aus Prednisolon und Chlorambucil sowie die intravenösen Immunglobuline herausgestellt. Wir präsentieren vier Fälle aus unserer Klinik sowie die aktuellen Ergebnisse der Literatur in diesem Mini‐Review und möchten damit die therapeutische Herausforderung sowie die Relevanz der Erarbeitung von Richtlinien unterstreichen.

Immune microenvironment associated with the severity of Langerhans cell histiocytosis in children

The aim of this study is to investigate the clinical potential of immune microenvironment in peripheral blood for the severity and therapeutic efficacy of Langerhans cell histiocytosis (LCH). A total of 200 newly diagnosed children with LCH during 10 years was enrolled for analysis in this study. Peripheral blood samples were acquired from patients before treatment in our hospital and immune indicators were detected by a four-color flow cytometer. The levels of CD3 + CD8 + T cell, CD3 + CD4 + HLA-DR + T cell, CD3 + CD8 + HLA-DR + T cell, IL-4, IL-6, IL-10 and IFN-γ in peripheral blood were markedly elevated in LCH patients vs. healthy controls. Patients with multiple system with risk organ involvement (MS-RO + ) exhibited higher levels in IL-6, IL-10 and IFN-γ, CD3 + CD4 + HLA-DR + T cell and CD3 + CD8 + HLA-DR + T cell, compared to those in patients without risk organ involvement (RO-). Patients who responded effectively to initial chemotherapy showed significantly lower levels of IL-4, IL-10, IFN-γ, CD3 + CD4 + HLA-DR + T cell and CD3 + CD8 + HLA-DR + T cell in peripheral blood, compared to those in patients who did not respond to initial chemotherapy. Furthermore, univariate analyses were performed that the higher levels of CD3 + CD4 + HLA-DR + T cells, CD3 + CD8 + HLA-DR + T cells and IL-10 in peripheral blood were related to non-response in LCH after initial chemotherapy. Immune microenvironment in peripheral blood may be associated with the severity and treatment response of LCH. The levels of CD3 + CD4 + HLA-DR + T cells, CD3 + CD8 + HLA-DR + T cells and IL-10 may be biomarkers to predict treatment response of LCH patients.

The changing landscape of pediatric histiocytoses: Birth, life, and transdifferentiation of pediatric histiocytes

Histiocytic neoplasms in the children are very rare, and histiocytoses can occur in the perinatal period. The presumed origins and presentation of specific histiocytoses in the pediatric age group are described. Common and newly described histiocytoses are presented including Langerhans cell histiocytosis, Rosai-Dorfman disease, histiocytic sarcoma, ALK positive histiocytosis, and hemophagocytic lymphohistiocytosis. Molecular findings common to pediatric histiocytoses are also discussed.

Therapy of necrobiotic xanthogranuloma - case series and review of the literature

Necrobiotic xanthogranuloma is a rare disease that is part of the non-Langerhans cell histiocytoses. It is characterized by yellowish skin lesions, which are typically periorbitally localized. Extracutaneous manifestations of all organs are possible and can cause potentially life-threatening complications. The disease also belongs to the facultative paraneoplasias and is often associated with paraproteinemia. These aspects should be considered regarding further diagnostics. Due to the rarity of the disease, there are no standardized guidelines for therapy so far. The combination of prednisolone and chlorambucil as well as intravenous immunoglobulins seem to be effective therapeutic options. We present four cases from our clinic as well as the current results of the literature in this mini-review and would like to highlight the therapeutic challenge as well as the need for the development of guidelines.

Rosai-Dorfman disease of the breast: a clinicoradiologic and pathologic study

Rosai-Dorfman disease (RDD) is an uncommon histiocytic disorder typically involving lymph nodes and less frequently extranodal tissues. RDD involving the breast is rare and may clinically and radiologically mimic neoplastic and non-neoplastic disorders. We report seven patients with breast RDD, describe their clinicoradiologic and pathologic features, and discuss the differential diagnosis. Patients, ranging from 15 to 74 years of age, presented with unilateral and unifocal (5/7) or bilateral and multifocal (2/7) masses. RDD was either confined to the breast (6/7) or concurrently involved a lymph node (1/7). Masses ranged from 8 to 31 mm, categorized as Breast Imaging-Reporting and Data System (BI-RADS) 4 (6/7) or 5 (1/7). All cases showed similar morphology with many large histiocytes displaying emperipolesis with associated fibrosis and dense lymphoplasmacytic infiltrate. The abnormal histiocytes co-expressed CD68/CD163, S100, OCT2, and Cyclin D1 (7/7), and were negative for CK AE1/AE3 (7/7), CD1a (7/7), and BRAF V600E (6/6). Flow cytometry (n = 3), kappa/lambda in situ hybridization (n = 5), and IgG4/IgG immunohistochemistry (n = 1) did not reveal lymphoma or IgG4-related disease. No mycobacterial or fungal organisms were identified on acid-fast bacillus (AFB) and Grocott methenamine silver (GMS) stains (n = 5). Three patients underwent complete excision and none recurred or progressed to systemic disease during follow-up (88-151 months). In summary, breast RDD should be included in the differential diagnosis of a mass-forming breast lesion. Histopathology with ancillary studies and clinicoradiologic correlation is essential for accurate diagnosis and optimal clinical management. Patients with RDD of the breast have an excellent prognosis after complete excision.

Langerhans cell histiocytosis: current advances in molecular pathogenesis

Langerhans cell histiocytosis (LCH) is a rare and clinically heterogeneous hematological disease characterized by the accumulation of mononuclear phagocytes in various tissues and organs. LCH is often characterized by activating mutations of the mitogen-activated protein kinase (MAPK) pathway with BRAFV600E being the most recurrent mutation. Although this discovery has greatly helped in understanding the disease and in developing better investigational tools, the process of malignant transformation and the cell of origin are still not fully understood. In this review, we focus on the newest updates regarding the molecular pathogenesis of LCH and novel suggested pathways with treatment potential.

Erdheim-Chester Disease Due to a Novel Internal Duplication of NRAS: Response to Targeted Therapy with Cobimetinib

Histiocytoses encompass a group of exceptionally rare disorders characterized by the abnormal infiltration of tissues by histocytes. Among these, Erdheim-Chester disease (ECD) stands out as a multisystem histiocytosis that typically affects bones and various other tissues. Historically, the treatment of ECD has been challenging. However, recent breakthroughs in our understanding, particularly the discovery of somatic mutations in the RAS-MAPK pathway, have opened new opportunities for targeted therapy in a significant subset of patients with ECD and other histiocytoses. In this report, we present the case of a patient with ECD harboring a previously unidentified microduplication in the NRAS gene in a small fraction of skin cells. This discovery played a pivotal role in tailoring an effective therapeutic approach involving kinase inhibitors downstream of NRAS. This case underscores the crucial role of deep sequencing of tissue samples in ECD, enabling the delivery of personalized targeted therapy to patients.

Recurrent Chemotherapy Treated Indeterminate Dendritic Cell Tumor: Case Report and Literature Review

Indeterminate dendritic cell tumor (IDCT) is an extremely uncommon histiocytic and dendritic neoplasms subtype that presents as single or multiple papules. There is currently no standard method for diagnosis and treatment, and the selection of therapeutic approaches is mainly based on successful examples of folk medicine. We describe a case of a pathology diagnosed indeterminate dendritic cell tumor, which shows the presence of CD1a, S100, and CD68, but lack langerin. She was treated with multi-chemotherapy regimens used to treat lymphoma and gained good results short term but was easy to recur. In addition, we reviewed the literature on the effectiveness and safety of chemotherapy in IDCT patients.

An effective treatment in Erdheim Chester disease: vemurafenib: a case report

BACKGROUND

Erdheim Chester disease (ECD) is a rare disease with multisystemic involvement in the group of non-langerhans cell histiocytosis. Although nearly 100 years have passed since its definition, the number of cases reported all over the world is below 1000. In addition to the rarity of the disease, low awareness seems to play a role in this.

CASE PRESENTATION

47-year-old white caucasian women patient who presented to our clinic with symptoms of weakness-fatigue as well as increasing pain in the knees and ptosis in the left eye. Result of the patient's bone biopsy, ECD was considered pathologically and BRAF V600E mutation was shown molecularly. After presenting the clinical, laboratory and other examination results of the case, the dramatic response seen with targeted therapy will be discussed.

CONCLUSIONS

BRAF V600E mutation is frequently seen in ECD. Vemurafenib plays an active role in targeted therapy.

Langerhans Cell Histiocytosis Showed Intense Uptake of 68 Ga-FAPI

ABSTRACT

A 23-year-old man was recently diagnosed with Langerhans cell histiocytosis (LCH). 68 Ga-FAPI PET/CT showed multiple lesions with intense FAPI uptake in the axial and appendicular skeleton with lytic or mixed bone destruction, consistent with osseous lesions of LCH. FAPI-avid foci around the right atrium and inferior vena cava, as well as micronodules and thin-walled cysts in the lungs, were also noted, possibly also involvement of LCH. This case suggested that 68 Ga-FAPI PET/CT may have the potential to be applied in evaluation of LCH.

Benign cephalic histiocytosis in a 2-year-old boy with an inconspicuous clinical presentation at onset

We report on a 2-year-old boy whose initially inconspicuous skin lesions later on evolved into a typical clinical presentation of benign cephalic histiocytosis (BCH). The diagnosis of BCH can often be made on clinical grounds without the need for an extensive diagnostic work-up. Given the benign and self-limited course of the disease treatment is not required and the clinical management can be limited to a watchful waiting approach.

Malignant Histiocytosis Comprises a Phenotypic Spectrum That Parallels the Lineage Differentiation of Monocytes, Macrophages, Dendritic Cells, and Langerhans Cells

Malignant histiocytoses (MHs), or the 'M group' of the Histiocyte Society classification, are characterized by neoplastic histiocytes with large pleomorphic nuclei. MH encompasses the diagnoses of histiocytic sarcoma, interdigitating dendritic cell sarcoma, and Langerhans cell sarcoma. We aimed to define the phenotypic spectrum of MH and examine the genotypic features across this spectrum. Using immunohistochemistry, we arranged the 22 cases into 4 subtypes that correspond to the lines of differentiation from monocytic and dendritic cell precursors as follows: (1) macrophage (n = 5): CD68+, CD163+, CD14+, and Factor 13a+; (2) monocyte-macrophage (n = 5): CD68+, CD163+, CD14+, S100+, and OCT2+; (3) dendritic cell (n = 6): CD68+, CD11c+, S100+, lysozyme+, ZBTB46+, and CD1a/langerin < 5%; and (4) Langerhans cell (n = 6): CD68+, CD11c+, S100+, ZBTB46+, CD1a+, and langerin+. The phenotypic subtypes align with those seen in low-grade histiocytic neoplasms as follows: MH-macrophage type correlates with Erdheim-Chester disease phenotype; MH-monocyte-macrophage type with Rosai-Dorfman disease phenotype, and MH-Langerhans cell type with Langerhans cell histiocytosis. Activating mutations in MAPK-pathway genes were identified in 80% of MH cases; 29% had mutations in the PI3k-AKT-mTOR pathway and 59% had mutations in epigenetic modulating genes. Strong expression of cyclin D1 was present in all cases, whereas p-ERK and p-AKT were not uniformly expressed. Eight of 22 (36%) MH cases were proven to be clonally related to a prior B-cell lymphoma. Defining the phenotypic spectrum of MH provides a guide to diagnosis and allows further exploration into the potential biological and clinical significance.

Implementing a Disease-specific Multidisciplinary Team and Order Set for Hemophagocytic Lymphohistiocytosis in a Pediatric Hospital

OBJECTIVE

To improve outcomes of hemophagocytic lymphohistiocytosis (HLH), prompt recognition and treatment are necessary. A HLH multidisciplinary team was implemented at our institution, and we established an electronic order set to foster uniformity in the diagnostic approach. The goal of this study is to capture the impact of this diagnostic tool.

METHODS

This is a retrospective study analyzing the utilization of a HLH-specific order set since time of implementation in June 2019 through December 2022. The trends in the utilization of the order set by providers were analyzed to evaluate the awareness and effectiveness of this tool.

RESULTS

The order set was utilized 50 times, most commonly by hematology/oncology (50%) and infectious disease (26%). Utilization by providers on newly presenting patients included 4 times in the year 2019, 12 times in 2020, 16 times in 2021, and 18 times in 2022. Utilization was associated with the diagnosis of HLH in 9 patients (18%).

CONCLUSION

Implementation of an HLH-specific order set facilitated a systematic method to approach patients with suspected HLH. The utilization of the order set displayed an upward trend over time, indicating support of this tool among these providers. This tool can increase awareness and early identification of HLH.

Serum levels of soluble interleukin 2 receptor (sIL-2R), tumor necrosis factor-alpha (TNF-α), and immunoglobulin M are correlated with the disease extent in childhood Langerhans cell histiocytosis

PURPOSE

This study aimed to identify peripheral parameters associated with the severity of Langerhans cell histiocytosis (LCH) and to look for indicators associated with improvement in LCH patients with risk-organ involvement.

METHODS

This study enrolled LCH patients who were assessed as active disease-better (AD-B) after treatment. Patients were divided into the single system (SS) group, multisystem disease without risk-organ involvement (RO- MS) group, and multisystem disease with risk-organ involvement (RO + MS) group. Serum cytokines, immunoglobulins, and lymphocyte subsets were measured at admission for all three groups. Changes in these indicators after treatment were also analyzed.

RESULTS

From January 2015 to January 2022, a total of 46 patients were recruited in the present study, including 19 patients (41.3%) in the SS group, 16 patients (34.8%) in the RO- MS group, and 11 patients (23.9%) in the RO + MS group. Serum levels of soluble interleukin 2 receptor (sIL-2R) (> 912.5 U/mL), tumor necrosis factor-alpha (TNF-α) (> 20.3 pg/mL), and immunoglobulin M (< 1.12 g/L) were found to be effective in identifying patients in the RO + MS group. Furthermore, the levels of sIL-2R (SS vs RO + MS: P = 0.002, RO- MS vs RO + MS: P = 0.018) and CD8 + T-cell count (SS vs RO + MS: P = 0.028) significantly declined in the RO + MS group after treatment, indicating disease improvement.

CONCLUSIONS

The levels of sIL-2R and TNF-α were positively correlated with the extent of disease, while the levels of IgM were negatively correlated with the extent of disease. Additionally, the levels of sIL-2R and CD8 + T-cell count could serve as useful indicators to evaluate the treatment response in RO + MS-LCH patients.

Expanding Our Knowledge of Molecular Pathogenesis in Histiocytoses: Solitary Soft Tissue Histiocytomas in Children With a Novel CLTC::SYK Fusion

The histiocytoses comprise a histopathologically and clinically diverse group of disorders bearing recurrent genomic alterations, commonly involving the BRAF gene and mitogen-activated protein kinase pathway. In the current study, a novel CLTC :: SYK fusion in 3 cases of a histopathologically distinct histiocytic neoplasm arising as solitary soft tissue lesions in children identified by next-generation sequencing and fluorescence in situ hybridization is described. Morphologically, all 3 neoplasms were composed of sheets of cells with round-oval nuclei and vacuolated eosinophilic cytoplasm but, in contrast to classic juvenile xanthogranuloma (JXG), Touton giant cells were absent. A separate cohort of classic JXG cases subsequently profiled by fluorescence in situ hybridization were negative for the presence of a CLTC::SYK fusion suggesting that CLTC::SYK fusion-positive histiocytoma is genetically and histologically distinct from JXG. We postulate that the CLTC::SYK fusion leads to aberrant activation of the SYK kinase, which is involved in variable pathways, including mitogen-activated protein kinase. The identification of a novel CLTC::SYK fusion may pave the way for the development of targeted therapeutic options for aggressive disease.

Novel paraneoplastic mechanism for cerebellar ataxia in Erdheim-Chester disease

We report a case of BRAF-mutation positive Erdheim-Chester disease presenting with a cerebellar ataxia. This is the first such case to be reported without structural MRI abnormalities but with a single intrathecally produced oligoclonal band. Now that the histiocytoses have been recharacterised as neoplastic, we speculate that the mechanism of the ataxia in our case is paraneoplastic. We highlight the importance of searching for BRAF mutations in this disease, as their presence leads to effective personalised treatments.

Hemophagocytic Lymphohistiocytosis and Pancreatic Cancer: A Rare Association

Introduction

Hemophagocytic lymphohistiocytosis (HLH) or hemophagocytic syndrome (HPS) is a life-threatening and relatively rare condition that usually presents as a multisystem febrile illness. It is associated with excessive activation of the immune system and hypercytokinemia, leading to an unregulated aggregation of macrophages and lymphocytes. Here, we present the first likely case of HLH with metastatic pancreatic carcinoma being the underlying etiology.

Case

A 44-year-old male with past medical history significant for heart transplant for which he was on tacrolimus, End-Stage Renal Disease (ESRD) on hemodialysis, recently treated CMV viremia, and necrotizing pancreatitis presented to the emergency with complaints of chills, decreased appetite, worsening non-bloody emesis, and dull left upper quadrant abdominal pain with radiation to the back for four days. No shortness of breath, fever, diarrhea, or blood in the stool was reported. Vitals on admission were blood pressure of 90/61 mmHg, a heart rate of 110 beats per minute, temperature of 98.1 °F, and respiratory rate of 18 per minute. Physical exam was significant for scleral icterus, decreased bibasilar breath sounds, moderate abdominal tenderness in the left flank and left upper abdominal quadrant without any palpable mass, and 1+ bilateral pedal edema. The remainder of the physical examination was benign. Electrocardiogram (EKG) showed sinus tachycardia without any ischemic changes, and chest x-ray showed mild pulmonary edema. Initial blood workup revealed WBC at 8.3 k/uL, hemoglobin of 10.2 g/dL, platelet count of 90 k/uL, and BUN/creatinine of 45/5.8 (baseline 40/5.0). Cardiac workup showed an elevated high sensitivity troponin level of 2479 pg/mL and brain natriuretic peptide (BNP) of 600 (0-100 pg/mL). The hepatobiliary profile showed an aspartate transaminase (AST) level of 2645 U/L, an alanine transaminase (ALT) of 2935 U/L, alkaline phosphatase (ALP) of 106 U/L, and lipase of 61 U/L, with total and conjugated bilirubin of 3.5 mg/dL and 2.1 mg/dL, respectively. Transthoracic echocardiogram (TTE) showed reduced left ventricular size with hyperdynamic systolic function. Computerized tomography (CT) scan of the abdomen (Fig. 1) revealed numerous new pulmonary nodules, ring-enhancing lesions within the liver, hyperenhancement of the pancreas with walled-off necrosis, and splenomegaly. Microbiological work-up was positive for cytomegalovirus (CMV) serologies (IgM and IgG) but absent viral load on Polymerase Chain Reaction (PCR). The initial diagnosis was systemic inflammatory respiratory syndrome (SIRS), likely septic versus distributive in the setting of pancreatitis, demand mediated non-ST segment elevation myocardial infarction (NSTEMI), and shock liver. Tacrolimus was held, and the patient was started on broad-spectrum antibiotics including vancomycin and cefepime for sepsis of unknown origin along with vasopressors for hypotension, requiring admission to the medical intensive care unit. Blood and urine cultures were collected on admission which remained negative throughout the course of hospital. CA19-9 levels were found elevated at 5587 U/mL. Liver biopsy was consistent with poorly differentiated adenocarcinoma of pancreatic origin. Both Infectious Disease and Hematology were consulted due to broad differential diagnoses. Due to the patient's continued hemodynamic instability and nonresponsiveness to the antibiotics, HLH was suspected with supporting labs as follows: ferritin 55,740 ng/mL (22-322 ng/mL), triglycerides 177 mg/dL (30-150 mg/dL), and fibrinogen 244 mg/dL (173-454 mg/dL), thus conferring 70-80% probability of HPS based on H-score. Soluble IL-2 R levels came out at 19,188 pg/mL (ref range 175-858 pg/mL). The patient couldn't be started on HLH treatment due to initial concerns of underlying infection and the delay in results of soluble IL-2 Receptor (IL-2 R) levels. The infection as a possible etiology was ruled out due to negative blood and urine cultures and HLH was attributed to pancreatic cancer. A marrow biopsy couldn't be pursued as the patient died within a week of hospitalization. An autopsy was not performed as per family's request.

Conclusion

HLH can occur secondary to solid cell malignancies including those from the pancreas and should be kept high in the differential in critically ill cancer patients who are nonresponsive to antibiotics. H-score has been reported to be a more sensitive tool compared to the HLH protocol, especially if used earlier during the presentation. Further research is needed to compare diagnostic efficacy for HLH protocol verses H-score especially in critically ill patients as they might benefit from steroid trial.

Clinical and prognostic features of Langerhans cell histiocytosis in adults

Langerhans cell histiocytosis (LCH) is a rare disease characterized by clonal expansion of CD1a+ CD207+ myeloid dendritic cells. The features of LCH are mainly described in children and remain poorly defined in adults; therefore, we conducted a nationwide survey to collect clinical data from 148 adult patients with LCH. The median age at diagnosis was 46.5 (range: 20-87) years with male predominance (60.8%). Among the 86 patients with detailed treatment information, 40 (46.5%) had single system LCH, whereas 46 (53.5%) had multisystem LCH. Moreover, 19 patients (22.1%) had an additional malignancy. BRAF V600E in plasma cell-free DNA was associated with a low overall survival (OS) rate and the risk of the pituitary gland and central nervous system involvement. At a median follow-up of 55 months from diagnosis, six patients (7.0%) had died, and the four patients with LCH-related death did not respond to initial chemotherapy. The OS probability at 5 years post-diagnosis was 90.6% (95% confidence interval: 79.8-95.8). Multivariate analysis showed that patients aged ≥60 years at diagnosis had a relatively poor prognosis. The probability of event-free survival at 5 years was 52.1% (95% confidence interval: 36.6-65.5), with 57 patients requiring chemotherapy. In this study, we first revealed the high rate of relapse after chemotherapy and mortality of poor responders in adults as well as children. Therefore, prospective therapeutic studies of adults with LCH using targeted therapies are needed to improve outcomes in adults with LCH.

Rosai-Dorfman Disease in a Pediatric Patient: Imaging Findings and Pathology with a brief review of the Literature

Rosai-Dorfman Disease, otherwise known as sinus histiocytosis with massive lymphadenopathy, is a rare form of non-Langerhans cell histiocytosis with an estimated incidence of 100 cases per year in the United States. Due to its variable presentation and nonspecific clinical findings, it is particularly difficult to diagnose in pediatric patients. We report a case of an 11-month-old male who presented with a 4-day history of a right groin mass. Ultrasound of the groin and pelvis demonstrated, and MRI of the abdomen and pelvis confirmed an inguinal mass with surrounding lymphadenopathy. Pathology confirmed Rosai-Dorfman Disease and the patient improved after starting oral steroid therapy. To the best of our knowledge, this is the first case of Rosai-Dorfman Disease involving the inguinal region in an infant under 1 year of age reported in the literature. In this case report, we discuss the imaging and histology findings as well as provide a brief literature review for this diagnosis.

A rare imaging presentation with multisystemic clinicopathological features of Langerhans cell histiocytosis: Case report and literature review

RATIONALE

Langerhans cell histiocytosis (LCH) is a kind of rare disease in which dendritic cells proliferate abnormally. It often occurs in children and can involve any tissue and organ. The affected sites usually include bone, skin, pituitary gland, and lungs, while the thyroid gland and external auditory canal are rarely observed. The perineal and labial involvement of this disease has not been reported yet.

PATIENT CONCERNS

A 47-year-old female patient experienced a swelling of the anterior neck area without an obvious inducement. She noticed a quail egg-like mass on the left side, and the mass increased progressively within 3 months. The anterior neck area was found to be swollen, and some flaky red rashes were seen on the scalp and bilateral external auditory canals.

DIAGNOSES

Imaging examination showed enlarged thyroid and cervical lymph nodes, multiple low-density nodules in the liver, and reduced signal in the posterior pituitary gland. The biopsy pathological result of the increased left cervical lymph node indicated that LCH was detected.

INTERVENTIONS

VP regimen (vincristine, dexamethasone per os) and related supportive treatments were given as inducing chemotherapy for 6 weeks.

OUTCOMES

After the second chemotherapy, the rash on the scalp and external auditory canal improved, and the neck mass was significantly reduced. After the third chemotherapy, the rash was mostly disappeared, while the neck lumps increased during chemotherapy. Thus, clatribine chemotherapy was recommended as the follow-up.

LESSONS

Imaging examinations played an important role in the diagnosis and follow-up of the disease, especially 18F-FDG PET/CT, which could show multiple involving organs at the same time. When a patient suffering from diabetes insipidus, skin rash, or fever, has a high FDG uptake PET/CT result in multiple tissues and organs throughout the body, it is necessary to consider the possibility of LCH.

Secondary hemophagocytic lymphohistiocytosis in children (Review)

Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening condition characterized by hyperinflammation in an uncontrolled and ineffective immune response. Despite great improvement in diagnosis and treatment, it still represents a challenge in clinical management, with poor prognosis in the absence of an aggressive therapeutic approach. The present literature review focuses on secondary HLH at pediatric age, which represents a heterogeneous group in terms of etiology and therapeutic approach. It summarizes the most recent evidence on epidemiology, pathophysiology, diagnosis, treatment and prognosis, and provides a detailed description and comparison of the major subtypes of secondary HLH. Finally, it addresses the open questions with a focus on diagnosis and new treatment insights.

Rosai-Dorfman-Destombes Disease in the Pediatric Head and Neck

BACKGROUND

Rosai-Dorfman-Destombes disease (RDD), or sinus histiocytosis with massive lymphadenopathy, is a rare form of non-Langerhans cells histiocytosis. It has a wide-ranging variability in presentation since first described in 1969 but much of its characteristics in children remain unknown.

METHODS

A retrospective chart review of children diagnosed with RDD at a tertiary care children's hospital was conducted from 2000 to 2021.

RESULTS

Twelve RDD patients were identified, with an average age of 7 years (SD 4.3). Males comprised 58% of the cohort, and African American ethnicity was most common (42%). Nodal RDD was found in 7 patients (58%). Nine patients (75%) presented RDD within the head and neck, 6 of whom had nodal RDD. The most common presentation was cervical lymphadenopathy, which most often involved levels V (67%), II (56%), III (44%), and I (11%), in order of frequency. Recurrence and persistence of disease after initial treatment was common, with 5 (42%) being disease free at the time of the last follow up. Fifty-eight percent (7/12) developed recurrence or had persistent disease and 4 required adjuvant systemic treatment with corticosteroids and/or chemotherapy. One patient succumbed after developing treatment related acute myelodysplastic leukemia (t-AML) from chemotherapy used to treat recurrent RDD.

CONCLUSION

Pediatric RDD presents at a young age and most commonly involving cervical lymphadenopathy. Ongoing surveillance in the setting of persistence or recurrence without clearly defined prognostic risk factors is important.

Langerhans Cell Histiocytosis of the Uvea with a Ciliochoroidal Mass: A Case Report of Management with Systemic Therapy

Background

This study is aimed at exploring a case of choroidal Langerhans cell histiocytosis (LCH) successfully treated with systemic corticosteroid and immunosuppressant. Case presentation. A 24-year-old man with known multisystem LCH developed loss of vision, ocular pain, conjunctival injection, panuveitis, and a ciliochoroidal mass. After receiving an intravenous methylprednisolone pulse, oral high-dose corticosteroids, and methotrexate, the mass resolved quickly and completely without flare-ups during 6 months of follow-up.

Conclusions

Intraocular involvement of LCH is rare and can present with or without a history of multisystemic disease. The diagnosis is challenging, and the standard treatment is not established. Systemic anti-inflammatory and immunosuppressive therapy could be an effective treatment, as the LCH itself contains an essential element of inflammation and the symptoms may be mainly inflammatory.

Characterizing Rosai-Dorfman disease with [18F]FDG PET/CT: a retrospective analysis of a single-center study

OBJECTIVES

Rosai-Dorfman disease (RDD) is a rare non-Langerhans cell histiocytic proliferative disorder. We performed a retrospective study to characterize the clinical and [18F]FDG PET/CT features of RDD.

METHODS

We retrospectively recruited 38 RDD patients with [18F]FDG PET/CT scan in our center. [18F]FDG PET/CT features were assessed, and clinical and follow-up data were recorded.

RESULTS

In the recruited patients, 20/38 (52.6%) patients had single-system disease, while others (18/38, 47.4%) had disease affecting multiple system. RDD most commonly involved the upper respiratory tract (47.4%), followed by cutaneous/subcutaneous lesion (39.5%), lymph node (36.8%), bone (31.6%), central nervous system (28.9%), and cardiovascular system (13.2%) in the recruited patients. In PET/CT, the RDD lesions were FDG-avid, and the SUVmax of the hottest lesion in an individual patient was positively correlated with C-reactive protein levels (r = 0.418, p = 0.014), and negatively correlated with hemoglobin levels (r =  -0.359, p = 0.036). The overall response rate of the first-line treatment was 80.8% in newly diagnosed RDD patients, and for patients with relapsed/progressive RDD, the overall response rate was 72.7%.

CONCLUSION

[18F]FDG PET/CT could be a useful tool for evaluating RDD.

KEY POINTS

• About half of the patients with Rosai-Dorfman disease had single-system disease, while others had disease affecting multiple system. Rosai-Dorfman disease most commonly involved the upper respiratory tract, followed by cutaneous/subcutaneous lesion, lymph node, bone, central nervous system, and cardiovascular system. • In [18F]FDG PET/CT, Rosai-Dorfman disease was usually hypermetabolic, and the SUVmax of the hottest lesion in an individual patient was positively correlated with C-reactive protein levels. • Rosai-Dorfman disease usually has a high overall response rate after treatment.

[Histiocytosis]

Histiocytosis is a group of rare diseases characterized by inflammation and accumulation of cells derived from monocytes and macrophages in different tissues. The symptoms are highly variable, from mild forms with involvement of a single organ to severe multisystem forms that can be life compromising. The diagnosis of histiocytosis is based on the clinic, radiological findings and pathological anatomy. A biopsy of the affected tissue is recommended in all cases as it may have therapeutic implications. During the last decade, some mutations have been identified in the affected tissue that condition activation of the MAPK/ERK and PI3K/AKT pathway, in a variable proportion depending on the type of histiocytosis. In this review we mainly focus on Langerhans Cell Histiocytosis, Erdheim-Chester Disease and Rosai-Dorfman Disease.

Mammary Rosai-Dorfman disease: Rare benign mimic of breast malignant neoplasm

Rosai-Dorfman disease (RDD), also known as sinus histiocytosis with massive lymphadenopathy, is an uncommon benign disorder characterized by the accumulation of activated histiocytes in affected tissues. While RDD typically involves lymph nodes, it may manifest as extranodal involvement. Breast involvement is an exceedingly rare presentation of this condition with <100 reported cases worldwide. This report presents a case of RDD in a 58-year-old male patient who presented with a palpable breast mass. Mammography and ultrasound imaging studies raised concerns for malignancy, prompting a breast biopsy. Histopathological examination revealed S100-positive pale histiocytes exhibiting emperipolesis, consistent with RDD. The management of extranodal RDD is individualized, as no standardized guidelines are currently available. However, surgical excision is recommended for unicentric breast lesions, which was performed in our case, resulting in complete remission. The patient has remained disease-free under surveillance with computed tomography scans. Our case underscores the importance of considering RDD in the differential diagnoses of breast masses and highlights the utility of surgical excision as an effective treatment option, especially for unicentric breast lesions of RDD.

H syndrome treated with Tocilizumab: two case reports and literature review

H syndrome is a rare autosomal recessive genetic disorder characterized by the following clinical features: cutaneous hyperpigmentation, hypertrichosis, hepatosplenomegaly, heart anomalies, hearing loss, hypogonadism, short stature, hallux valgus, hyperglycemia, fixed flexion contractures of the toe joints, and the proximal interphalangeal joints. In rare cases, autoinflammatory and lymphoproliferative manifestations have also been reported. This disorder is due to loss-of-function mutations in SLC29A3 gene, which encode the equilibrative nucleoside transporter ENT3. This deficiency leads to abnormal function and proliferation of histiocytes. H syndrome is part of the R-group of histiocytosis. We report two different cases, one was diagnosed in adulthood and the other in childhood. The first case reported is a 37-year-old woman suffering from H syndrome with an autoinflammatory systemic disease that begins in adulthood (fever and diffuse organ's infiltration) and with cutaneous, articular, auditory, and endocrinological manifestations since childhood. The second case reported is a 2-year-old girl with autoinflammatory, endocrine, and cutaneous symptoms (fever, lymphadenopathy, organomegaly, growth delay, and cutaneous hyperpigmentation). Homozygous mutations in SLC29A3 confirmed the diagnosis of H syndrome in both cases. Each patient was treated with Tocilizumab with a significant improvement for lymphoproliferative, autoinflammatory, and cutaneous manifestations. Both cases were reported to show the multiple characteristics of this rare syndrome, which can be diagnosed either in childhood or in adulthood. In addition, an overview of the literature suggested Tocilizumab efficiency.

Successful treatment of non-Langerhans cell histiocytosis with the MEK inhibitor trametinib: a multicenter analysis

Erdheim-Chester disease (ECD) and Rosai-Dorfman disease (RDD) are rare non-Langerhans cell histiocytoses (non-LCHs), for which therapeutic options are limited. MAPK pathway activation through BRAFV600E mutation or other genomic alterations is a histiocytosis hallmark and correlates with a favorable response to BRAF inhibitors and the MEK inhibitor cobimetinib. However, there has been no systematic evaluation of alternative MEK inhibitors. To assess the efficacy and safety of the MEK inhibitor trametinib, we retrospectively analyzed the outcomes of 26 adult patients (17 with ECD, 5 with ECD/RDD, 3 with RDD, and 1 with ECD/LCH) treated with orally administered trametinib at 4 major US care centers. The most common treatment-related toxicity was rash (27% of patients). In most patients, the disease was effectively managed at low doses (0.5-1.0 mg trametinib daily). The response rate of the 17 evaluable patients was 71% (73% [8/11] without a detectable BRAFV600E achieving response). At a median follow-up of 23 months, treatment effects were durable, with a median time-to-treatment failure of 37 months, whereas the median progression-free and overall survival were not reached (at 3 years, 90.1% of patients were alive). Most patients harbored mutations in BRAF (either classic BRAFV600E or other BRAF alterations) or alterations in other genes involved in the MAPK pathway, eg, MAP2K, NF1, GNAS, or RAS. Most patients required lower than standard doses of trametinib but were responsive to lower doses. Our data suggest that the MEK inhibitor trametinib is an effective treatment for ECD and RDD, including those without the BRAFV600E mutation.

Vemurafenib for BRAF V600-mutant Erdheim-Chester disease presenting with bilateral orbital involvement

ECD is considered to have rapid progression and poor prognosis. Studies have shown that vemurafenib is effective for ECD patients with orbital involvement, but not for ECD with multiple organs. The refinement of treatment approaches and the increased awareness of ECD have led to a dramatic improvement in prognosis.

Langerhans cell histiocytosis located in the spheno-orbital bone and the pons: illustrative case

BACKGROUND

This is a case of aggressive Langerhans cell histiocytosis (LCH) with an atypical intracranial location.

OBSERVATIONS

In this report, the authors present the diagnosis and treatment of a 12-year-old male patient diagnosed with LCH. The patient was admitted to the emergency department with left-sided facial palsy, and a solid lesion with mass effect in the pons was found. A biopsy was performed via suboccipital craniotomy, and the diagnosis was LCH. A chemotherapy regimen was started since the LCH sample was the resistant type. The patient showed improvement in his neurological deficit following treatment.

LESSONS

This rare localized and aggressive case's diagnosis process and treatment choices may apply to future cases.

Prevalence, patterns and outcomes of cardiac involvement in Erdheim-Chester disease

AIMS

Cardiac involvement of Erdheim-Chester disease (ECD), a rare L group histiocytosis, has been reported to be associated with poor outcomes, but systematic studies are lacking. The present study aimed to investigate the prevalence, clinical features, imaging features, and prognosis of cardiac involvement in ECD in a large series.

METHODS AND RESULTS

All patients with ECD who underwent cardiac magnetic resonance (CMR) imaging between 2003 and 2019 at a French tertiary center were retrospectively included. Primary outcome was all-cause mortality. Secondary outcomes were pericarditis, cardiac tamponade, conduction disorders, device implantation and coronary artery disease (CAD). A total of 200 patients were included [63 (54-71) years, 30% female, 58% BRAFV600E mutated]. Median follow-up was 5.5 years (3.3-9 years). On CMR, right atrioventricular sulcus infiltration was observed in 37% of patients, and pericardial effusion was seen in 24% of patients. In total, 8 patients (4%) had pericarditis (7 acute, 1 constrictive), 10 patients (5%) had cardiac tamponade, 5 patients (2.5%) had ECD-related high-degree conduction disorders, and 45 patients (23%) had CAD. Overall, cardiac involvement was present in 96 patients (48%) and was associated with BRAFV600E mutation [Odds ratio (OR) = 7.4, 95% confidence interval (CI) (3.5-16.8), P < 0.001] and ECD-related clinical events [OR = 5, 95%CI (1.5-21.2), P = 0.004] but not with lower survival in multivariate analysis [adjusted hazard ratio (HR) = 1.4, 95% CI (0.8-2.5), P = 0.2].

CONCLUSION

Cardiac involvement is present in nearly half of ECD patients and is associated with BRAFV600E mutation and complications (pericarditis, cardiac tamponade, and conduction disorders) but not with lower survival.

[Combined histiocytosis of the Langerhans group (Langerhans cell histiocytosis and Erdheim-Chester disease) in a 64-year-old man with BRAF and NRAS mutations: a case report]

We present a case of a 64-year-old male with a history of Crohn's disease who presented with an episode of acute abdominal pain. He was being investigated for a dermatological lesion. A skin and lung biopsy both revealed histiocytosis of the "L" (Langerhans) group. The skin biopsy showed a proliferation of histiocytic cells expressing Langerin, CD1a and S100 and the molecular study was positive for the BRAF p.V600E mutation. In the lung biopsy, a proliferation of histiocytic cells was found, which were positive for CD68 and S100 and negative for Langerin and CD1a; mutations in NRAS c.38G>A in exon 2 (p.G13D) were also detected.

Incidental Detection of Ilium Langerhans Cell Histiocytosis on 99m Tc-DTPA Renal Dynamic Scintigraphy

ABSTRACT

We report the case of a 24-year-old man who underwent 99m Tc-DTPA scintigraphy for the evaluation the renal function. This scan incidentally showed an abnormal uptake of 99m Tc-DTPA in the left lower abdominal region. SPECT/CT fusion images showed osteolytic bone destruction in the left ilium associated with soft tissue mass and elevated DTPA uptake. Biopsy pathology of the ilium lesion demonstrated Langerhans cell histiocytosis.

18 F-FDG PET/CT in Extensive Follicular Dendritic Cell Sarcoma With Response Assessment to Chemotherapy

ABSTRACT

Follicular dendritic cell sarcoma (FDCS) is a low-grade sarcoma of mesenchymal dendritic cell origin, and it constitutes <0.4% of soft tissue sarcomas. We report a rare case of FDCS in a 32-year-old man. 18 F-FDG PET/CT demonstrated the involvement of cervical, axillary, mediastinal, abdominal, and pelvic groups of lymph nodes and spleen. A cervical lymph node biopsy suggested FDCS. 18 F-FDG PET/CT scan done after 3 cycles of chemotherapy (CHOP regime) revealed a complete metabolic response. This case presents the rarity of extensive presentation and complete response to the CHOP regime.

Molecular and clinicopathologic characterization of pediatric histiocytoses

The spectrum of somatic mutations in pediatric histiocytoses and their clinical implications are not fully characterized, especially for non-Langerhans cell histiocytosis (-LCH) subtypes. A cohort of 415 children with histiocytosis from the French histiocytosis registry was reviewed and analyzed for BRAFV600E . Most BRAFWT samples were analyzed by next-generation sequencing (NGS) with a custom panel of genes for histiocytosis and myeloid neoplasia. Of 415 case samples, there were 366 LCH, 1 Erdheim-Chester disease, 21 Rosai-Dorfman disease (RDD), 21 juvenile xanthogranuloma (JXG, mostly with severe presentation), and 6 malignant histiocytosis (MH). BRAFV600E was the most common mutation found in LCH (50.3%, n = 184). Among 105 non-BRAFV600E -mutated LCH case samples, NGS revealed mutations as follows: MAP2K1 (n = 44), BRAF exon 12 deletions (n = 26), and duplications (n = 8), other BRAF V600 codon mutation (n = 4), and non-MAP-kinase pathway genes (n = 5). Wild-type sequences were identified in 17.1% of samples. BRAFV600E was the only variant significantly correlated with critical presentations: organ-risk involvement and neurodegeneration. MAP-kinase pathway mutations were identified in seven RDD (mostly MAP2K1) and three JXG samples, but most samples were wild-type on NGS. Finally, two MH samples had KRAS mutations, and one had a novel BRAFG469R mutation. Rarely, we identified mutations unrelated to MAP-kinase pathway genes. In conclusion, we characterized the mutational spectrum of childhood LCH and clinical correlations of variants and subtypes. Variants responsible for JXG and RDD were not elucidated in more than half of the cases, calling for other sequencing approaches.

Neuroimaging of pediatric tumors of the sellar region-A review in light of the 2021 WHO classification of tumors of the central nervous system

Sellar/suprasellar tumors comprise about 10% of all pediatric Central Nervous System (CNS) tumors and include a wide variety of entities, with different cellular origins and distinctive histological and radiological findings, demanding customized neuroimaging protocols for appropriate diagnosis and management. The 5th edition of the World Health Organization (WHO) classification of CNS tumors unprecedently incorporated both histologic and molecular alterations into a common diagnostic framework, with a great impact in tumor classification and grading. Based on the current understanding of the clinical, molecular, and morphological features of CNS neoplasms, there have been additions of new tumor types and modifications of existing ones in the latest WHO tumor classification. In the specific case of sellar/suprasellar tumors, changes include for example separation of adamantinomatous and papillary craniopharyngiomas, now classified as distinct tumor types. Nevertheless, although the current molecular landscape is the fundamental driving force to the new WHO CNS tumor classification, the imaging profile of sellar/suprasellar tumors remains largely unexplored, particularly in the pediatric population. In this review, we aim to provide an essential pathological update to better understand the way sellar/suprasellar tumors are currently classified, with a focus on the pediatric population. Furthermore, we intend to present the neuroimaging features that may assist in the differential diagnosis, surgical planning, adjuvant/neoadjuvant therapy, and follow-up of this group of tumors in children.

A primary Rosai-Dorfman-Destombes disease of the scalp: case report and literature review

Background

Rosai-Dorfman-Destombes disease (RDD) was first described in 1965 as a benign histiocytic proliferative disorder of unknown cause. Cases of RDD limited to cutaneous tissue have been reported over the past few decades, but single cutaneous RDD of the scalp is rare.

Case presentation

We report a 31-year-old male with a lump on the parietal scalp without extranodal lesion lasting 1 month with gradual enlargement. The surgical incision ruptured with purulent after the first resection. Then the patient was treated with plastic surgery after disinfection and antibiotic treatment. Finally, he recovered well and discharged after 20 days.

Conclusions

RDD of the scalp is rare. Surgical incision can cure the lesion but it may become infected because of increased lymphocytic infiltration. Early diagnosis and differential diagnosis of RDD are necessary. For treatment, individualized therapy is critical to patient prognosis.

Incidental Diagnosis of Oligosymptomatic Bilateral Perirenal Erdheim-Chester Disease during Emergency Investigation for COVID-19 Infection

Erdheim-Chester disease (ECD), a rare form of non-Langerhans histiocytosis, is a multisystem disorder. The case reported here refers to a 49-year-old man presenting at the emergency room with respiratory symptoms. While undergoing diagnostic tests for COVID-19 infection, tomography revealed asymptomatic bilateral perirenal tumors, while renal function remained unaltered. ECD was suggested as an incidental diagnosis and confirmed by core needle biopsy. This report provides a brief description of the clinical, laboratory, and imaging findings in this case of ECD. This diagnosis, albeit rare, should be taken into consideration in the context of incidental findings of abdominal tumors to ensure that treatment, when required, is instituted early.

Erdheim-Chester disease and vemurafenib: a review of ophthalmic presentations and clinical outcomes

PURPOSE

To provide a comprehensive review of ocular and orbital manifestations of Erdheim-Chester Disease (ECD) and compare clinical outcomes with vemurafenib (INN) to historical treatments (HT). Primary outcomes are ophthalmic findings on presentation, changes in visual acuity, and mortality rate. Secondary outcomes include the progression of ocular findings, systemic involvements, and treatment modalities.

METHODS

All published literature from January 1983 to March 2021 was searched for ophthalmic manifestations of ECD. Clinical outcomes following HT were collected and compared with INN.

RESULTS

Forty-seven patients with ECD and ophthalmic presentations were identified. The mean age was 49.6 years (SD = 15.0). Proptosis (65.6%) and extraocular muscle restrictions (42.5%) were the most common presenting signs. Of 41 (87.2%) patients with orbital masses on radiologic examination, 90.2% were bilateral, and 53.7% were located in the intraconal space. Ophthalmic examination was significant for xanthelasma (27.2%), optic disc edema (34.0%), and subretinal changes (21.3%). Common treatments were systemic steroids (76.6%), interferon-α (17.0%), and cyclophosphamide (14.9%). INN was less commonly used (12.8%). The mean change in logMAR visual acuity declined with HT (29.9%) but improved with INN (79.1%) (p > 0.05). The proportion of eyes with complete vision loss increased after HT (p < 0.05). The overall mortality rate was 27.7% and notably higher in the HT group (29.3%) when compared to the INN group (16.7%) (p > 0.05).

CONCLUSION

ECD presents with many ophthalmic manifestations. Although the intraocular treatments remain controversial, INN should be highly considered in treating orbital ECD patients with BRAF-V600E mutations to prevent and reverse vision loss.

TYMS promotes genomic instability and tumor progression in Ink4a/Arf null background

We previously showed that elevated TYMS exhibits oncogenic properties and promotes tumorigenesis after a long latency, suggesting cooperation with sequential somatic mutations. Here we report the cooperation of ectopic expression of human TYMS with loss of Ink4a/Arf, one of the most commonly mutated somatic events in human cancer. Using an hTS/Ink4a/Arf -/- genetically engineered mouse model we showed that deregulated TYMS expression in Ink4a/Arf null background accelerates tumorigenesis and metastasis. In addition, tumors from TYMS-expressing mice were associated with a phenotype of genomic instability including enhanced double strand DNA damage, aneuploidy and loss of G1/S checkpoint. Downregulation of TYMS in vitro decreased cell proliferation and sensitized tumor cells to antimetabolite chemotherapy. In addition, depletion of TYMS in vivo by TYMS shRNA reduced tumor incidence, delayed tumor progression and prolonged survival in hTS/Ink4a/Arf -/- mice. Our data shows that activation of TYMS in Ink4a/Arf null background enhances uncontrolled cell proliferation and tumor growth, supporting the development of new agents and strategies targeting TYMS to delay tumorigenesis and prolong survival.