Reduced expression of semaphorin 3A in osteoclasts causes lymphatic expansion in a Gorham-Stout disease (GSD) mouse model. / ç ´éª¨ç»†èƒžä¸­ä¿¡å·ç´ 3Aè¡¨è¾¾çš„å‡å°‘å¯¼è‡´å°é¼ GSDæ¨¡åž‹ä¸­æ·‹å·´ç®¡æ‰©å¼ .

Gorham-Stout disease (GSD) is a sporadic chronic disease characterized by progressive bone dissolution, absorption, and disappearance along with lymphatic vessel infiltration in bone-marrow cavities. Although the osteolytic mechanism of GSD has been widely studied, the cause of lymphatic hyperplasia in GSD is rarely investigated. In this study, by comparing the RNA expression profile of osteoclasts (OCs) with that of OC precursors (OCPs) by RNA sequencing, we identified a new factor, semaphorin 3A (Sema3A), which is an osteoprotective factor involved in the lymphatic expansion of GSD. Compared to OCPs, OCs enhanced the growth, migration, and tube formation of lymphatic endothelial cells (LECs), in which the expression of Sema3A is low compared to that in OCPs. In the presence of recombinant Sema3A, the growth, migration, and tube formation of LECs were inhibited, further confirming the inhibitory effect of Sema3A on LECs in vitro. Using an LEC-induced GSD mouse model, the effect of Sema3A was examined by injecting lentivirus-expressing Sema3A into the tibiae in vivo. We found that the overexpression of Sema3A in tibiae suppressed the expansion of LECs and alleviated bone loss, whereas the injection of lentivirus expressing Sema3A short hairpin RNA (shRNA) into the tibiae caused GSD-like phenotypes. Histological staining further demonstrated that OCs decreased and osteocalcin increased after Sema3A lentiviral treatment, compared with the control. Based on the above results, we propose that reduced Sema3A in OCs is one of the mechanisms contributing to the pathogeneses of GSD and that expressing Sema3A represents a new approach for the treatment of GSD.

Reduced expression of semaphorin 3A in osteoclasts causes lymphatic expansion in a Gorham-Stout disease (GSD) mouse model / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Gorham-Stout disease (GSD) is a sporadic chronic disease characterized by progressive bone dissolution, absorption, and disappearance along with lymphatic vessel infiltration in bone-marrow cavities. Although the osteolytic mechanism of GSD has been widely studied, the cause of lymphatic hyperplasia in GSD is rarely investigated. In this study, by comparing the RNA expression profile of osteoclasts (OCs) with that of OC precursors (OCPs) by RNA sequencing, we identified a new factor, semaphorin 3A (Sema3A), which is an osteoprotective factor involved in the lymphatic expansion of GSD. Compared to OCPs, OCs enhanced the growth, migration, and tube formation of lymphatic endothelial cells (LECs), in which the expression of Sema3A is low compared to that in OCPs. In the presence of recombinant Sema3A, the growth, migration, and tube formation of LECs were inhibited, further confirming the inhibitory effect of Sema3A on LECs in vitro. Using an LEC-induced GSD mouse model, the effect of Sema3A was examined by injecting lentivirus-expressing Sema3A into the tibiae in vivo. We found that the overexpression of Sema3A in tibiae suppressed the expansion of LECs and alleviated bone loss, whereas the injection of lentivirus expressing Sema3A short hairpin RNA (shRNA) into the tibiae caused GSD-like phenotypes. Histological staining further demonstrated that OCs decreased and osteocalcin increased after Sema3A lentiviral treatment, compared with the control. Based on the above results, we propose that reduced Sema3A in OCs is one of the mechanisms contributing to the pathogeneses of GSD and that expressing Sema3A represents a new approach for the treatment of GSD.

Clinical and radiological improvement in Gorham-Stout disease after sirolimus treatment.

BACKGROUND: Gorham-Stout disease (GSD) is a rare syndrome characterized by lymphatic malformations, mainly in bone structures, causing progressive osteolysis. Lymphatic endothelial cell proliferation depends on several growth factors that use the phosphoinositide-3 kinase (PI3K)/Akt pathway and converge on the mammalian target molecule of the rapamycin (mTOR) pathway. These findings have allowed treating GSD with mTOR pathway inhibitors such as sirolimus or everolimus. CASE REPORT: We present the case of a one-year-old female patient referred to our institution after a right femur fracture and progressive limb volume increase, disproportionately to the trauma. After several episodes of soft tissue infections, imaging studies showed pseudarthrosis, lytic lesions, and progressive loss of the right femur that ended in total absence. A femur biopsy showed lymphatic structures positive with D2-40 staining, diagnosing GSD. After six months of non-response to traditional treatments, the limb was disarticulated at the hip level, and oral sirolimus treatment was initiated, showing clinical and radiological improvement with minor lytic lesions and evidence of ossification after 20 months of treatment. CONCLUSIONS: Oral sirolimus treatment for GSD inhibits angiogenesis and osteoclastic activity, stimulating bone anabolism and leading to arrested osteolysis progression and improved ossification, quality of life, and patient prognosis. Therefore, sirolimus should be considered a therapeutic option for this rare disease.

INTRODUCCIÓN: La enfermedad de Gorham-Stout es un trastorno poco frecuente caracterizado por malformaciones linfáticas localizadas sobre estructuras óseas que causan osteólisis progresiva. La proliferación de células endoteliales linfáticas depende de factores de crecimiento que utilizan la vía de la fosfoinositida-3 cinasa (PI3K)/Akt y convergen en la vía de la molécula diana de rapamicina de los mamíferos (mTOR). Este conocimiento ha permitido el tratamiento de esta enfermedad con inhibidores de esta vía como sirolimus o everolimus. CASO CLÍNICO: Se presenta el caso de una paciente de sexo femenino de un año referida a nuestra institución tras presentar fractura de fémur derecho y aumento de volumen de dicha extremidad posterior a un traumatismo. Después de diversos episodios de infecciones de tejidos blandos se realizaron estudios de imagen que mostraron pseudoartrosis, lesiones líticas y ausencia total del fémur derecho, así como una biopsia de fémur que mostró estructuras vasculares positivas con tinción D2-40, diagnosticándose enfermedad de Gorham-Stout. Durante su abordaje, se realizó la desarticulación de la extremidad a nivel de la cadera y se inició tratamiento con sirolimus oral, presentando una mejoría clínica y radiológica con menores lesiones líticas y evidencia de osificación posterior a 20 meses de tratamiento. CONCLUSIONES: El tratamiento con sirolimus oral para la enfermedad de Gorham-Stout inhibe la actividad osteoclástica y la angiogénesis, estimulando el anabolismo óseo que resulta en la detención de la progresión de la osteólisis y una mejoría en la osificación, la calidad de vida y el pronóstico del paciente. Por tal motivo, el sirolimus debe considerarse como una opción terapéutica para esta enfermedad.

Gorham-Stout disease affecting the spine with cerebrospinal fluid leakage and Chiari-like tonsillar herniation: a rare case report and review of literature.

BACKGROUND: Gorham-Stout disease (GSD) is a very rare disorder characterized by massive osteolysis of poorly understood aetiology. The association between GSD involving the skull base and cerebrospinal fluid (CSF) leakage has been reported in the literature. However, few cases of CSF leakage and Chiari-like tonsillar herniation in GSD involving the spine have been reported. CASE PRESENTATION: We present the case of a 20-year-old man with GSD involving the thoracic and lumbar spine, which caused CSF leakage and Chiari-like tonsillar herniation. The patient underwent four spinal surgeries for osteolytic lesions of the spine over a 10-year period. Here, we discuss the possible aetiology of the development of CSF leakage. Epidural blood patch (EBP) was performed at the T11-T12 level to repair the CSF leakage. After EBP treatment, rebound intracranial hypertension (RIH) developed, and tonsillar herniation disappeared 2 months later. CONCLUSIONS: GSD involving the spine with CSF leakage and Chiari-like tonsillar herniation is relatively rare. For patients who have undergone multiple spinal surgeries, minimally invasive treatment is an alternative treatment for CSF leakage. EBP can repair CSF leakage secondary to GSD and improve chronic brain sagging, with reversibility of Chiari-like malformations.

Complex Lymphatic Anomalies: Report on a Patient Registry Using the Latest Diagnostic Guidelines.

Background: Generalized lymphatic anomaly (GLA), Gorham-Stout disease (GSD), kaposiform lymphangiomatosis (KLA), and central conducting lymphatic anomaly (CCLA) are rare, multisystem lymphatic disorders, referred to as complex lymphatic anomalies (CLAs). Their etiology remains poorly understood; however, somatic activating mutations have recently been discovered, and the results of targeted treatments are promising. This study aimed to elaborate on the phenotypic description of CLA. Methods: Thirty-six consecutive patients were recruited for the "GLA/GSD Registry" of the University Hospital of Freiburg, Germany (2015-2021). Clinical data were prospectively collected provided that a signed informed consent form was obtained. The latest proposed diagnostic guidelines were retrospectively applied. Results: Thirty-two patients (38% males) were included in the study; 15 GLA, 10 GSD, 3 KLA, and 4 CCLA patients were identified. Eighty-four percent already had symptoms by the age of 15 years. Osteolysis and periosseous soft-tissue infiltration were associated with GSD (p < 0.001 and p = 0.011, respectively), ascites and protein-losing enteropathy with CCLA (p = 0.007 and p = 0.004, respectively), and consumption coagulopathy with KLA (p = 0.006). No statistically significant differences were found in organ involvement, distribution of osteolytic lesions, number of affected bones and fractures. Twenty-five patients had complications; one patient with GLA died despite multimodal treatment. Spontaneous regression was seen in one patient with untreated KLA. Conclusions: CLA are rare, and their overlapping clinical presentations make differential diagnosis difficult. The characterization of our case series contributes to the phenotypic description and differentiation of these four clinical entities. A further understanding of their pathogenesis is crucial for evaluating targeted therapies and optimizing medical care.

Thoracic Gorham-Stout disease masquerading as an ovarian malignancy: a differential diagnosis in non-malignant causes of raised Ca-125 and overview of this rare pathology.

Gorham-Stout disease (GSD) is thought to be due to uncontrolled proliferation of vascular and lymphatic structures within bone tissue causing destruction and osteolysis of bone. We present a patient in her mid-40s who reported chronic shoulder pain, a pleural effusion and irregular periods. Investigations showed osteolysis of her ribs, pleural effusions, an ovarian mass and a raised carbohydrate antigen 125 (Ca-125). She was subsequently diagnosed with GSD, and referred to gynaecology-oncology in consideration of potential ovarian malignancy. GSD is a diagnosis of exclusion that requires a high degree of clinical suspicion, as well as multiple investigations to achieve diagnosis. Clinicians rely on a small number of case reports to provide guidance for this. Therefore, this report provides an overview of a rare pathology, considers the differentials of a raised Ca-125 and describes how a pleural effusion, which links them both, alarmed us regarding an incidental finding of an ovarian cyst.

[Complicated lymphatic anomaly: a clinicopathological analysis of four cases].

Objective: To investigate the clinicopathological features, clinical manifestations and different diagnosis of patients with complicated lymphatic anomaly. Methods: The clinical and pathologic data of four patients with complicated lymphatic anomaly diagnosed and treated in Peking Union Medical College Hospital from January 2000 to December 2021 were collected and analyzed. Results: One Gorham-Stout disease case and three generalized lymphatic anomaly cases were included in this cohort. Patients' ages ranged from 7 to 32 years. There were three males and one female. The positions of biopsy included three bone biopsy and one bronchus biopsy. Microscopically, all cases showed diffuse enlarged lymphatic channels. At the same time, osteogenesis was obvious in Gorham-Stout disease case. Radiologically, cortical loss was seen in Gorham-Stout disease, and lytic bone confined to the medullary cavity presented in generalized lymphatic anomaly. The three generalized lymphatic anomaly cases also had coagulopathy, and two had effusion. Conclusions: The histologic feature of complicated lymphatic anomaly was diffuse lymphatic malformation, and the diagnosis depends on clinical and pathologic information. The treatment and prognosis of these diseases are different, and therefore it is necessary to understand their clinical and pathologic features and make the correct diagnosis.

Gorham Stout disease of the temporal bone with cerebrospinal fluid leak.

Gorham Stout disease (GSD) is a rare disease characterized by the proliferation of endothelial lined vessels and replacement of bone by fibrous tissue. The main imaging features are progressive osteolysis and cortical resorption. Temporal bone involvement is rare but presents as a destructive bone lesion that may be misinterpreted as more common lytic processes in the pediatric population, such as infection or Langerhans cell histiocytosis. GSD of the temporal bone is associated with cerebrospinal fluid (CSF) leaks, may present with otorrhea, and can mimic other causes of ear drainage. Here, we report the clinical course, imaging features, and outcomes of a 3-year-old girl with GSD of the temporal bone presenting with CSF leak initially attributed to infection.

KRAS-driven model of Gorham-Stout disease effectively treated with trametinib.

Gorham-Stout disease (GSD) is a sporadically occurring lymphatic disorder. Patients with GSD develop ectopic lymphatics in bone, gradually lose bone, and can have life-threatening complications, such as chylothorax. The etiology of GSD is poorly understood, and current treatments for this disease are inadequate for most patients. To explore the pathogenesis of GSD, we performed targeted high-throughput sequencing with samples from a patient with GSD and identified an activating somatic mutation in KRAS (p.G12V). To characterize the effect of hyperactive KRAS signaling on lymphatic development, we expressed an active form of KRAS (p.G12D) in murine lymphatics (iLECKras mice). We found that iLECKras mice developed lymphatics in bone, which is a hallmark of GSD. We also found that lymphatic valve development and maintenance was altered in iLECKras mice. Because most iLECKras mice developed chylothorax and died before they had significant bone disease, we analyzed the effect of trametinib (an FDA-approved MEK1/2 inhibitor) on lymphatic valve regression in iLECKras mice. Notably, we found that trametinib suppressed this phenotype in iLECKras mice. Together, our results demonstrate that somatic activating mutations in KRAS can be associated with GSD and reveal that hyperactive KRAS signaling stimulates the formation of lymphatics in bone and impairs the development of lymphatic valves. These findings provide insight into the pathogenesis of GSD and suggest that trametinib could be an effective treatment for GSD.

A somatic activating KRAS variant identified in an affected lesion of a patient with Gorham-Stout disease.

Gorham-Stout disease (GSD), a rare disorder of unknown etiology, is characterized by massive osteolysis that is associated with proliferation and dilation of lymphatic vessels. Variants in cancer-associated genes have been described in complex lymphatic anomalies. To explore the pathogenesis of GSD, we performed the amplicon-based deep sequencing on 50 cancer-related genes to assay affected tissues from the six patients with GSD. In one patient, a somatic activating KRAS c.182A > G variant (p.Q61R) was detected in 1% of the tissue sample. Conversely, the mutant allele was not detected in uninvolved normal skin and blood samples. Histopathology of the patient's tissue sample showed proliferation of abnormal lymphatic and blood vascular endothelial cells, osteoclasts, and activated macrophages. The activating KRAS variant is a known 'hotspot' variant, frequently identified in several types of human cancer. This is the first report of identifying a pathogenic variant in a patient with GSD. This finding may set the stage for elucidation of pathophysiology and the development of novel therapies for GSD.

A Large Skull Defect Due to Gorham-Stout Disease: Case Report and Literature Review on Pathogenesis, Diagnosis, and Treatment.

A 24-year old man was referred to the Erasmus MC Bone Center because of an asymptomatic increasing skull defect of the left parietal bone. The defect was first noticed at the age of six, and gradually increased over the years. His medical history was unremarkable, without any known trauma and a negative family history for bone diseases. Laboratory tests showed a low vitamin D level without other abnormalities. Particularly, there was no increase in markers of inflammation or bone turnover. CT-scans of the skull showed an osteolytic region of the parietal skull bone, with a two-centimeter increase in diameter over 9 years. Contrast enhanced MRI showed lymphangiogenic invasion, which was compatible with our suspicion of Gorham-Stout disease. The patient was referred to the neurosurgeon for treatment with a bone graft while considering additional drug treatment. Gorham-Stout or vanishing bone disease is a rare entity characterized by progressive osteolysis with lymphangiogenic bone invasion. Although already reported in 1838, currently the diagnosis and treatment of Gorham-Stout disease is still challenging. The underlying pathophysiology is not clarified yet and several theories exist. The disease usually affects persons younger than 40 years and the majority present with bone disease of the maxillofacial region, the upper extremities or the torso. The clinical presentation includes most frequently pain, swelling, and functional impairment of the affected region, but the disease can also be asymptomatic. Laboratory investigations are usually normal, and diagnosis is based upon imaging and sometimes pathology examination of affected bone tissue. Treatment is experimental and there is no general consensus about the best option due to lack of randomized controlled trials. Case reports showed patients treated with bisphosphonates, interferon-alpha, anti-VEGF therapy, mTOR inhibitors, and radiotherapy. There are some reports of surgery with prosthetic or bone grafts but no long-term follow-up data exist. This paper describes a unique case of Gorham-Stout disease of the parietal skull bone and discusses the current state of knowledge about this rare bone disease.

Gorham-Stout disease: good results of bisphosphonate treatment in 6 of 7 patients.

Background and purpose - Gorham-Stout disease (GSD) is a rare mono- or polyostotic condition characterized by idiopathic intraosseous proliferation of angiomatous structures resulting in progressive destruction and resorption of bone. Little is known about the course of disease and no previous study has evaluated patients' quality of life (QoL).Patients and methods - This is a retrospective analysis of 7 consecutive patients (5 males) with a median age at diagnosis of 14 years and a median follow-up of 7 years who were diagnosed with GSD in our department between 1995 and 2018. Data regarding clinical, radiographic, and histopathological features, and treatment, as well as sequelae and their subsequent therapy, were obtained. QoL was assessed by Musculoskeletal Tumor Society Score (MSTS), Toronto Extremity Salvage Score (TESS), and Reintegration to Normal Living (RNL) Index.Results - 3 patients had a monoostotic and 4 patients a polyostotic disease. Besides a diagnostic biopsy, 4 of the 7 patients had to undergo 8 surgeries to treat evolving sequelae. Using an off-label therapy with bisphosphonates in 6 patients, a stable disease state was achieved in 5 patients after a median of 20 months. The median MSTS, TESS, and RNL Index at last follow-up was between 87% and 79%.Interpretation - Due to its rare occurrence, diagnosis and treatment of GSD remain challenging. Off-label treatment with bisphosphonates appears to lead to a stable disease state in the majority of patients. QoL varies depending on the individual manifestations but good to excellent results can be achieved even in complex polyostotic cases with a history of possibly life-threatening sequelae.

Multifocal Gorham-Stout disease associated with Chiari I malformation and recurrent aseptic meningitis: Case report and review of literature.

Gorham-Stout disease is a rare condition of uncertain aetiology characterised by lymphatic proliferation within osseous structures and subsequent massive osteolysis. This report describes the index case of a patient with multifocal Gorham-Stout disease involving the skull base with Chiari I malformation and recurrent aseptic meningitis without fistula. A five-year-old male presented following decompression of a Chiari I malformation with headaches, vomiting, and stiff neck and cerebrospinal fluid pleocytosis without growth of a pathogenic organism. Ongoing symptoms prompted a further three presentations over several months revealing persistent aseptic cerebrospinal fluid monocytic pleocytosis. Further investigation revealed multifocal osseous cystic disease and subsequent bone biopsy suggested Gorham-Stout disease. Suboccipital decompression was not repeated despite craniocervical junction re-stenosis. A literature review demonstrated the extreme rarity of Gorham-Stout disease associated with Chiari I malformation and meningitis. Potential mechanisms of these entities occurring in concert are discussed. Consideration of Gorham-Stout disease as a secondary cause for Chiari I malformation is important amid local bone changes or cerebrospinal fluid leakage prior to pursuing suboccipital decompression considering the poor outcomes reported.

Dracorhodin perchlorate inhibits osteoclastogenesis through repressing RANKL-stimulated NFATc1 activity.

Osteolytic skeletal disorders are caused by an imbalance in the osteoclast and osteoblast function. Suppressing the differentiation and resorptive function of osteoclast is a key strategy for treating osteolytic diseases. Dracorhodin perchlorate (D.P), an active component from dragon blood resin, has been used for facilitating wound healing and anti-cancer treatments. In this study, we determined the effect of D.P on osteoclast differentiation and function. We have found that D.P inhibited RANKL-induced osteoclast formation and resorbed pits of hydroxyapatite-coated plate in a dose-dependent manner. D.P also disrupted the formation of intact actin-rich podosome structures in mature osteoclasts and inhibited osteoclast-specific gene and protein expressions. Further, D.P was able to suppress RANKL-activated JNK, NF-κB and Ca2+ signalling pathways and reduces the expression level of NFATc1 as well as the nucleus translocation of NFATc1. Overall, these results indicated a potential therapeutic effect of D.P on osteoclast-related conditions.

Vascular Floor of Mouth Mass with Unanticipated Intracranial, Orbital, and Vertebral Associated Involvements.

We report on a case in which a blanching, unobtrusive oral growth proved to be a systemic threat. A blind, epileptic child presented with a bleeding oral floor mass of 4 weeks. Biopsy showed small, dilated vascular spaces with reactive fibroblasts. MRI indicated distribution of expansile lesions in the mandible, cranial base, and right orbit that had possibly contributed to the patient's years-long neurologic deficits. A subsequent bone scan indicated lesions in multiple axial bones. Histologic markers confirmed the presentation of a rare cystic vascular pathology. Cystic Angiomatosis is a disease of intraosseous vascular malformations with occasional visceral involvements. Oral and craniomaxillofacial cases are especially rare and presentations can involve neuropsychiatric deficits, sensory issues, and mucosal bleeding. While clinicians are often dismissive of intraoral bleeding because of the prevalence of periodontal disease, careful evaluation is nonetheless critical to rule out underlying diseases with a possibly significant systemic involvement.

Multiple photopenic vertebrae in the bone scintigraphy of a young man with Gorham disease: CT and MRI correlation.

We report a rare pattern of extensive bone abnormalities on the Tc-99m MDP bone scintigraphy in a patient with Gorham disease. This rare condition is the result of vascular and lymphatic channel proliferation in bony structures which induce bone resorption. Our case is a 28-year-old man with a history of biopsy-proven soft tissue hemangioma in the left thigh, encountered with a recent diagnosis of multiple vertebral hemangiomata in the axial skeleton and progressive bony destructions in the pelvis on CT and MRI images, referred for bone scintigraphy. Multiple photopenic hemangiomata were noted on bone scan.

Gorham-Stout Syndrome of the Shoulder Girdle Successfully Controlled by Antiresorptive Agents: A Report of 2 Cases.

CASE: Gorham-Stout disease (GSD) is a rare disorder characterized by massive bone destruction. Consensus is lacking on the effective treatment strategies for GSD. This report presents 2 cases of GSD, a 47-year-old man and a 72-year-old woman, involving the shoulder girdle which were successfully controlled by antiresorptive agents including bisphosphonates and denosumab, the antireceptor activator of nuclear factor-κB ligand antibody. CONCLUSIONS: These 2 cases suggest that antiresorptive agents targeting osteoclasts can be efficacious therapeutic options for GSD. This is the first case of GSD we are aware of which showed good response to denosumab treatment.