Gorham-Stout case report: a multi-omic analysis reveals recurrent fusions as new potential drivers of the disease.

BACKGROUND: Gorham-Stout disease is a rare condition characterized by vascular proliferation and the massive destruction of bone tissue. With less than 400 cases in the literature of Gorham-Stout syndrome, we performed a unique study combining whole-genome sequencing and RNA-Seq to probe the genomic features and differentially expressed pathways of a presented case, revealing new possible drivers and biomarkers of the disease. CASE PRESENTATION: We present a case report of a white 45-year-old female patient with marked bone loss of the left humerus associated with vascular proliferation, diagnosed with Gorham-Stout disease. The analysis of whole-genome sequencing showed a dominance of large structural DNA rearrangements. Particularly, rearrangements in chromosomes seven, twelve, and twenty could contribute to the development of the disease, especially a gene fusion involving ATG101 that could affect macroautophagy. The study of RNA-sequencing data from the patient uncovered the PI3K/AKT/mTOR pathway as the most affected signaling cascade in the Gorham-Stout lesional tissue. Furthermore, M2 macrophage infiltration was detected using immunohistochemical staining and confirmed by deconvolution of the RNA-seq expression data. CONCLUSIONS: The way that DNA and RNA aberrations lead to Gorham-Stout disease is poorly understood due to the limited number of studies focusing on this rare disease. Our study provides the first glimpse into this facet of the disease, exposing new possible therapeutic targets and facilitating the clinicopathological diagnosis of Gorham-Stout disease.

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.

Successful Management of Gorham-Stout Disease in Scapula and Ribs: A Case Report and Literature Review.

Gorham-Stout disease (GSD) is an extremely rare bone condition of unknown etiology characterized by spontaneous and progressive resorption of bones. GSD can occur at any age and is not related to gender, genetic inheritance, or race. Any part of the skeleton can be affected and the symptoms correlate with the sites involved. The diagnosis of GSD is established based on the combination of clinical, radiologic, and histologic features after excluding other diseases. Because of its rarity, current knowledge is limited to case reports and there is no agreement on the best strategy for treatment. The following case report describes a successfully treated case of GSD in a 26-year-old male patient with the left scapula and the 7th-9th left ribs involved. The patient was diagnosed with osteoporosis-related pleural effusion at a local hospital. In our institution, the patient was diagnosed with GSD and treated with radiotherapy and bisphosphonate. The disease was controlled and there was no evidence of disease progression during follow-up. Genetic sequencing was performed to investigate the etiology of GSD. In addition, the present study reviews the theories regarding the etiology, the clinical manifestations, the diagnostic approaches, and treatment options for this rare disease.

The Impact of Mast Cell Density on the Progression of Bone Disease in Multiple Myeloma Patients.

BACKGROUND: Osteolytic bone disease is a major hallmark in multiple myeloma (MM) progression and affects many patients. Several inflammatory cells are involved in MM progression. Among them, mast cells (MCs) accumulated in the bone marrow (BM) microenvironment are known to play an important role in the mechanism of neovascularization. METHODS: In 52 newly diagnosed active MM patients, we measured BM MC density (MCD) using an immunohistochemical stain for tryptase, serum levels of matrix metalloproteinase-9 (MMP-9) and receptor activator of nuclear factor x03BA;B ligand (RANKL) by a solid-phase sandwich enzyme-linked immunosorbent assay, along with urine levels of N-terminal propeptide of procollagen type I (Ntx) by a competitive inhibition enzyme-linked immunosorbent assay, in various clinical stages and skeletal grades. RESULTS: MCD, RANKL and Ntx were higher in MM patients. All values increased in association with both the clinical stage and skeletal grade. Furthermore, MCD correlated positively with MMP-9, RANKL and Ntx. CONCLUSIONS: Our data suggest that MCs may contribute to osteolytic processes during MM progression. Although the major role of MCs in tumor progression is to enhance angiogenesis, it seems that they may affect MM bone disease and may secrete a plethora of mediators that may directly and indirectly have an impact on osteolysis.

Rare bone diseases and their dental, oral, and craniofacial manifestations.

Hereditary diseases affecting the skeleton are heterogeneous in etiology and severity. Though many of these conditions are individually rare, the total number of people affected is great. These disorders often include dental-oral-craniofacial (DOC) manifestations, but the combination of the rarity and lack of in-depth reporting often limit our understanding and ability to diagnose and treat affected individuals. In this review, we focus on dental, oral, and craniofacial manifestations of rare bone diseases. Discussed are defects in 4 key physiologic processes in bone/tooth formation that serve as models for the understanding of other diseases in the skeleton and DOC complex: progenitor cell differentiation (fibrous dysplasia), extracellular matrix production (osteogenesis imperfecta), mineralization (familial tumoral calcinosis/hyperostosis hyperphosphatemia syndrome, hypophosphatemic rickets, and hypophosphatasia), and bone resorption (Gorham-Stout disease). For each condition, we highlight causative mutations (when known), etiopathology in the skeleton and DOC complex, and treatments. By understanding how these 4 foci are subverted to cause disease, we aim to improve the identification of genetic, molecular, and/or biologic causes, diagnoses, and treatment of these and other rare bone conditions that may share underlying mechanisms of disease.

Induction of retinol-binding protein 4 and placenta-specific 8 expression in human prostate cancer cells remaining in bone following osteolytic tumor growth inhibition by osteoprotegerin.

New drugs that inhibit the osteoprotegerin (OPG)/receptor activator of NF-κB ligand (RANKL)/RANK pathway have demonstrated efficacy for the treatment of bone metastasis. Toxicities induced by these drugs, however, including osteonecrosis of the jaw and hypocalcemia, may adversely affect therapy. The aim of this study was to identify additional therapeutic targets that can be combined with OPG/RANKL/RANK pathway inhibition in the treatment of prostate cancer bone metastasis. We established a stable transfectant that produces high levels of OPG mRNA and protein from PC-3 human prostate cancer cells (PC3-OPG). The culture medium of PC3-OPG cells significantly inhibited the differentiation of mouse monocytes into mature osteoclasts. Furthermore, when PC3-OPG cells were injected into the bones of nude mice, bone destruction and tumor-induced osteoclast formation were reduced. Injection into bone of the mixtures containing equal amounts of green fluorescent protein (GFP)-expressing PC-3 cells (PC3-GFP) and PC3-OPG cells also reduced bone destruction, compared to the control mixture. PC3-GFP cells were subsequently isolated from bone tumors and used for microarray analysis to assess changes in gene expression following osteolytic tumor growth inhibition by OPG. We selected the top 10 upregulated genes based on results from microarrays and confirmed mRNA expression of each gene by RT-PCR. The expression patterns of retinol-binding protein 4 (RBP4) and placenta-specific 8 (PLAC8) were consistent with microarray results. Expression of these genes was also increased in the bone tumors of PC3-GFP/PC3-OPG-injected mice. Knockdown of both RBP4 and PLAC8 by siRNA inhibited the growth of PC-3 cells in vitro. Thus, RBP4 and PLAC8 may become new therapeutic targets for prostate cancer bone metastasis, in combination with OPG/RANKL/RANK pathway inhibition.

PTEN hamartoma tumor syndrome and Gorham-Stout phenomenon.

PTEN: hamartoma tumor syndrome (PHTS) is a group of syndromes caused by mutations in PTEN. Gorham-Stout phenomenon (GSP) is a rare condition characterized by proliferation of vascular structures in bones, resulting in progressive osteolysis. Here we present a 1-year-old boy with PHTS and GSP. The lesion that later proved to be GSP was evident from the age of 4 months, and became symptomatic at the age of 1 year. Eventually, he developed a fatal chylothorax. Mutation analysis revealed a germline heterozygous mutation c.517 C>T (p.Arg173Cys) in exon 6 of PTEN. Analysis of the lymphatic malformation (LM) tissue revealed no loss of heterozygosity (LOH) nor a second, somatic PTEN mutation of the remaining wild type allele. The germline p.Arg173Cys mutation was also present in the mother and the propositus' younger sister and brother. Further molecular work-up showed a heterozygous variant c.2180C>T (p.Ala727Val) FLT4 in the LM tissue, which was also present in the germline of mother and two siblings. GSP has not been reported before in a patient with a PTEN mutation. Up to this date, this mutation is the only genetic defect possibly involved in the etiology of GSP which is plausible given the known function of PTEN in angiogenic signaling.

Massive cranial osteolysis, skin changes, growth retardation and developmental delay: Gorham syndrome with systemic manifestations?

We report on a 16-month-old girl with multiple swellings on her skull due to massive osteolysis, growth retardation, facial anomalies, and wrinkly skin with mosaic hypopigmentation. She also had severe hypercalcemia, which gradually returned to normal levels. The condition likely represents Gorham syndrome with systemic manifestations.

Absence of MMP2 mutation in idiopathic multicentric osteolysis with nephropathy.

The genetic basis of idiopathic multicentric osteolysis with nephropathy is unknown. This disorder is typically a sporadic, but sometimes an autosomal dominant, condition featuring carpal-tarsal destruction and nephropathy causing renal failure. Loss-of-function mutation within the gene encoding matrix metalloproteinase 2 (MMP2) causes the autosomal recessive disorder nodulosis-arthropathy-osteolysis syndrome characterized by carpal-tarsal destruction, subcutaneous nodules, and generalized osteoporosis. We questioned whether sporadic idiopathic multicentric osteolysis with nephropathy is allelic with nodulosis-arthropathy osteolysis syndrome and undertook sequence analysis of the matrix metalloproteinase 2 gene in three unrelated affected boys. Although symptoms appeared by age 2 years, idiopathic multicentric osteolysis was diagnosed at ages 5, 5, and 12 years with flares of pain and limited motion or swelling of wrists, ankles, elbows, knees, and shoulders. Proteinuria was present on referral at ages 8, 7, and 12 years, respectively. Kidney transplantation was necessary for one boy at age 17 years. Coding exons and adjacent mRNA splice sites of the matrix metalloproteinase 2 gene were analyzed by polymerase chain reaction amplification and DNA sequencing. Matrix metalloproteinase 2 gene analysis was negative for mutation in the three patients. Sequence analysis of the matrix metalloproteinase 2 gene shows sporadic idiopathic multicentric osteolysis with nephropathy is not allelic to nodulosis-arthropathy-osteolysis syndrome. The genetic bases of idiopathic multicentric osteolysis disorders remain unknown.

A novel homozygous MMP2 mutation in a family with Winchester syndrome.

The 2001 International Classification of Constitutional Disorders of Bone has included in the group of multicentric hands and feet osteolysis syndromes three autosomal recessive inherited disorders: Winchester, Torg and nodulosis-arthropathy-osteolysis (NAO) syndromes. Nosographic delineations of these rare syndromes are difficult to define, and there is no consensus. In 2001, two mutations in the matrix metalloproteinase 2 gene (MMP2) have been identified in two families with a NAO phenotype. In a recent study, a homozygous MMP2 mutation has also been identified in a patient presenting with Winchester syndrome. We report the clinical evolution of two sisters with a Winchester phenotype. Clinical review over 23 years provides information on the general evolution of osteolysis and points to an intrafamilial variation with clinical and radiological changes during the patients' life. In both sisters, we identified a new homozygous mutation in the catalytic domain of the MMP2 gene. Our study results are consistent with the involvement of MMP2 in Winchester syndrome and with the hypothesis that Winchester and NAO syndromes are allelic disorders that form a continuous clinical spectrum. At last, our observation emphasizes the interest of molecular analysis in genetic counselling of this consanguineous family.

Hereditary bilateral conductive hearing loss caused by total loss of ossicles: a report of familial expansile osteolysis.

OBJECTIVE: The objective of this study was to report on three members of a family with familial expansile osteolysis; the important point about these patients was that none of them had middle-ear ossicles. STUDY DESIGN AND SUBJECTS: A retrospective case review including three cases with familial expansile osteolysis. SETTING: Department of Otolaryngology in a tertiary referral center. INTERVENTIONS: Each patient underwent computerized tomography of the temporal bone in the coronal view, audiometric and tympanometric evaluations, biochemical investigation, whole body isotope scans by Tc-99 mMDP and X-ray. Also the patients' pedigree was studied. Two of the patients had exploratory middle-ear surgery as well. RESULTS: The temporal-bone computed-tomography scan in the coronal view of all three patients and also exploratory middle-ear surgery, which was done on two of the patients, showed no ossicles in the middle ear of either ear in all three cases. This feature hadn't been reported in previous studies. Hearing loss was revealed in the medical histories since childhood. Audiometry indicated mild to moderate conductive and mixed hearing loss and also an AD-type tympanogram pattern along with an absence of acoustic reflexes in both ears of the cases. Both serum alkaline phosphatase and hydroxyproline levels were elevated. There was an increase in uptake and activity at multiple foci of the whole skeleton. No improvement in hearing thresholds was obtained after reconstruction of the middle ear. CONCLUSION: The total absence of middle-ear ossicles can probably be regarded as a new symptom in some patients with familial expansile osteolysis. Common ossiculoplasty for improving the hearing thresholds in this condition may be unsuccessful; therefore, both surgeons and patients must be completely aware of the contingent undesirable results.

[Familial expansive osteolysis otological and dental manifestations of genetic origin]. / L'ostéolyse expansive familiale. Manifestations otologiques et dentaires d'origine génétique.

OBJECTIVES: Familial Expansive Osteolysis (FEO) ist a rare autosomal dominant bone dysplasia. The disease can show general and focal skeletal alterations, the latter having a predominantly peripheral distribution. Onset occurs after the second decade of life. PATIENTS AND METHODS: We present the study, of 30 years, of a family consisting of 49 members covering five generations. RESULTS: Among the 35 members studied, 18 have familial expansive osteolysis (FEO). The first clinical sign of the condition is transmission deafness at an early age. The features of the teeth has a unique and characteristic appearance. Thinning of the cortical bone leads to severe, painful, disabling deformities. Serum alkaline phosphatase, and urinary hydroxyproline and deoxipyridinoline are elevated. Calcium and parathyroid hormone are normal. Treatment with diphosphonates, calcitonin and vitamin D has been unsuccessful. We present the surgical technology and the results to short and long term of 13 interventions on 8 patients. CONCLUSION: Progressive osteoclastic reabsorption accompanied by weak osteoblastic activity results in medullary expansion characterized by rarefaction of the bone marrow, which is replaced by fibrous tissue and fat. FEO is histologically similar to Paget disease, but the age of onset, the distribution of the bone lesions, the dental and middle ear alterations, and the clinical progression are different. These features also differentiate FEO from fibrous dysplasia, fibrocystic osteitis and imperfect osteogenesis. The gene responsible for FEO is located in the 18q21-22 chromosome region. Mutations in TNFRSF11A, the gene encoding receptor activator of nuclear factor-kappa-B (RANK), has been recently identified as the cause of FEO. A duplication of 18 base pairs in exon 1 of the TNFRSF11A gene suggests that this corresponds to the site of the anomaly and can be considered a "hot spot" for mutations.

Talo-patello-scaphoid osteolysis, synovitis, and short fourth metacarpals in sisters: a new syndrome?

Osteolysis syndromes are characterized by resorption of affected bones with associated swelling and pain. Various forms of multicentric osteolysis syndromes including autosomal dominant and recessive carpal-tarsal osteolysis, Torg, François, Whyte-Hemingway, Hajdu-Cheney, Winchester, and other forms have been described. Most present in pre-school years with extensive involvement and destruction of multiple bones. We present a sister-pair, both of whom presented in early teenage, i.e., 13 and 15.5 years, respectively, with bilateral ankle, knee, and later, wrist pain. Radiological examination revealed bilateral osteolysis of tali, scaphoids, and patellae, and short fourth metacarpals in both sisters. Further investigation revealed absence of renal involvement, a normal excretion of amino acids, mucopolysaccharides and oligosaccharides, and presence of chronic synovitis in both sisters. Both parents and a younger brother were without radiographic or clinical evidence of the disease and there was no history of consanguinity. Thus, our sister-pair presented with the same carpal and tarsal bone involvement at a much later age, with evidence of chronic synovitis, along with short fourth metacarpals (brachydactyly type E changes) and without renal disease, suggesting a new syndrome with probable autosomal recessive inheritance.

[Heterogenicity of Gorham-Stout syndrome: association with lymphatic and venous malformations]. / Heterogenicidad del síndrome de Gorham-Stout: asociación a malformaciones linfáticas y venosas.

INTRODUCTION: Gorham-Stout syndrome is a rare disorder of unknown etiology characterized by osteolysis and microscopic proliferation of abnormal vessels. We report two cases of this syndrome associated with lymphatic and venous malformations. CASE REPORTS: The first case is a 5-year-old boy with disseminated lymphangiomatosis of poor prognosis, with significant pleural involvement and osteolytic lesions. The second case is a 5-year-old girl with a diagnosis of Klippel-Trenaunay syndrome with significant skeletal involvement of the lower extremities and secondary pathological fracture. CONCLUSIONS: Gorham-Stout syndrome may occasionally be associated with various lymphatic and venous malformations. Osteolysis and bone resorption may be induced by lymphatic bone involvement.

New syndrome of hypotrichosis, striate palmoplantar keratoderma, acro-osteolysis and periodontitis not due to mutations in cathepsin C.

We report a mother and daughter with a syndrome of hypotrichosis, striate palmoplantar keratoderma, onychogryphosis, periodontitis, acro-osteolysis and psoriasis-like skin lesions. The syndrome resembles Papillon-Lefèvre syndrome (PLS), characterized by palmoplantar keratoderma, periodontitis and psoriasis-like skin lesions, and particularly Haim-Munk syndrome, an allelic variant of PLS with acro-osteolysis. Both are caused by mutations in the cathepsin C gene (CTSC). Our patients differ in the unique nature of the palmar keratoderma and hypotrichosis. We have sequenced CTSC in the mother without finding mutations in either coding or non-coding parts of the gene. We propose that our patients suffer from a new syndrome possibly caused by mutations in a gene that has a functional or structural relation with CTSC.

Hajdu--Cheney syndrome: evolution of phenotype and clinical problems.

Hajdu-Cheney syndrome is a rare, autosomal dominant disorder comprising acroosteolysis of the distal phalanges with associated digital abnormalities, distinctive craniofacial and skull changes, dental anomalies, and proportionate short stature. The clinical and radiologic characteristics of Hajdu-Cheney syndrome develop and progress with age. Many of the medical problems that arise in this syndrome cluster in specific age ranges. Case reports of six affected individuals in two additional families and a summary of the English literature is presented with emphasis on the changing physical findings and medical sequelae over time.