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KRAS gain-of-function mutations are frequently observed in sporadic arteriovenous malformations. The mechanisms underlying the progression of such KRAS-driven malformations are still incompletely understood, and no treatments for the condition are approved. Here, we show the effectiveness of sotorasib, a specific KRAS G12C inhibitor, in reducing the volume of vascular malformations and improving survival in two mouse models carrying a mosaic Kras G12C mutation. We then administered sotorasib to two adult patients with severe KRAS G12C-related arteriovenous malformations. Both patients had rapid reductions in symptoms and arteriovenous malformation size. Targeting KRAS G12C appears to be a promising therapeutic approach for patients with KRAS G12C-related vascular malformations. (Funded by the European Research Council and others.).

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SOLAMEN syndrome is a rare, recently recognized congenital syndrome that is characterized by progressive and hypertrophic diseases involving multiple systems, including segmental overgrowth, lipomatosis, arteriovenous malformation (AVM) and epidermal nevus. According to literatures, SOLAMEN syndrome is caused by heterozygous PTEN mutation. Phenotypic overlap complicates the clinical identification of diseases associated with PTEN heterozygous mutations, making the diagnosis of SOLAMEN more challenging. In addition, SOLAMEN often presents with segmental tissue overgrowth and vascular malformations, increasing the possibility of misdiagnosis as klipple-trenaunay syndrome or Parks-Weber syndrome. Here, we present a case of a child presenting with macrocephaly, patchy lymphatic malformation on the right chest, marked subcutaneous varicosities and capillaries involving the whole body, overgrowth of the left lower limb, a liner epidermal nevus on the middle of the right lower limb, and a large AVM on the right cranial thoracic entrance. Based on the typical phenotypes, the child was diagnosed as SOLAMEN syndrome. detailed clinical, imaging and genetic diagnoses of SOLAMEN syndrome was rendered. Next-generation sequencing (NGS) data revealed that except for a germline PTEN mutation, a PDGFRB variant was also identified. A subsequent echocardiographic examination detected potential cardiac defects. We suggested that given the progressive nature of AVM and the potential severity of cardiac damage, regular echocardiographic evaluation, imaging follow-up and appropriate interventional therapy for AVM are recommended.

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Arteriovenous malformations (AVMs) are congenital vascular anomalies with a poor prognosis. AVMs are considered intractable diseases, as there is no established approach for early diagnosis and treatment. Therefore, this study aimed to provide new evidence by analyzing microRNAs (miRNAs) associated with AVM. We present fundamental evidence for the early diagnosis and treatment of AVM by analyzing miRNAs in the endothelial cells of AVMs. This study performed sequencing and validation of miRNAs in endothelial cells from normal and AVM tissues. Five upregulated and two downregulated miRNAs were subsequently analyzed under hypoxia and vascular endothelial growth factor (VEGF) treatment by one-way analysis of variance (ANOVA). Under hypoxic conditions, miR-135b-5p was significantly upregulated in the AVM compared to that under normal conditions, corresponding to increased endothelial activity (p-value = 0.0238). VEGF treatment showed no significant increase in miR-135b-5p under normal conditions, however, a surge in AVM was observed. Under both hypoxia and VEGF treatment, comparison indicated a downregulation of miR-135b-5p in AVM. Therefore, miR-135b-5p was assumed to affect the pathophysiological process of AVM and might play a vital role as a potential biomarker of AVMs for application related to diagnosis and treatment.

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SummaryHereditary haemorrhagic telangiectasia (HHT) has an estimated prevalence of 1 in 5000-8000 individuals globally with pulmonary arteriovenous malformations (PAVMs) affecting approximately 15%-50% of HHT patients. Ischaemic stroke is a known complication of PAVMs that affects ≤30% of patients with PAVMs. Studies have shown that patients with PAVMs have ischaemic stroke a decade earlier than routine stroke. The predominant mechanism of ischaemic stroke in HHT patients is paradoxical embolism due to PAVMs, but most HHT-related PAVMs are asymptomatic. Additionally, HHT is often underdiagnosed in patients and poses a challenge to physicians due to its rarity. We present a case of a patient with ischaemic stroke who was subsequently diagnosed with HHT and found to have a PAVM on further evaluation. This case highlights the importance of using an individualised patient-centred stroke evaluation and screening for PAVMs in patients who had a stroke with possible or suspected HHT and definite HHT.

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This case report describes a 53-year-old man with multiple erythematous macules and papules diffusely distributed on the frontal area, cheeks, eyelids, nose, and supralabial skin.

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High-flow vascular malformations have been associated with multiple syndromes including capillary malformation-arteriovenous malformation (CM-AVM) syndrome, hereditary hemorrhagic telangiectasia syndrome, and less commonly, phosphatase and tensin homolog hamartoma tumor syndrome (PHTS). We present a series of three patients with clinically challenging complex AVMs who were found to have underlying PHTS. In all patients, diagnosis was delayed, and the presence of the AVM prompted sampling and genetic testing for PHTS in the absence of other clinical features of the condition. This series highlights the importance of screening for PHTS in the setting of high-flow vascular malformations.

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Capillary malformation-arteriovenous malformation is a rare autosomal dominant disorder associated with EPHB4 loss-of-function mutations. We report the unique presentation of a 6-year-old girl with multiple capillary malformations in a unilateral segmental distribution affecting the right hemiface, right upper chest, and right arm associated with overgrowth. Targeted next-generation sequencing on a tissue sample revealed a novel heterozygotic variant in the EPHB4 gene (NM_004444.5 (EPHB4): c.715T>A, p.[Cys239Ser]). This case highlights a distinct presentation of CM-AVM type 2 and showcases a new variant in EPHB4 not previously reported in the literature.

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BACKGROUND AND PURPOSE: Pulmonary arteriovenous malformations (PAVMs) may cause recurrent brain abscess. The primary aim was to determine the prevalence of PAVM amongst survivors of brain abscess. The proportion with cardiac right-to-left shunts was also assessed post hoc. METHODS: This was a cross-sectional population-based study of adult (≥18 years) survivors of cryptogenic bacterial brain abscess in Denmark from 2007 through 2016. Patients were invited for bubble-echocardiography to detect vascular right-to-left shunting and, if abnormal, subsequent computed tomography thorax for diagnosis of PAVM. Data are presented as n/N (%) or median with interquartile range (IQR). RESULTS: Study participation was accepted by 47/157 (30%) eligible patients amongst whom two did not appear for scheduled bubble-echocardiography. The median age of participants was 54 years (IQR 45-62) and 19/57 (33%) were females compared with 59 years (IQR 48-68, p = 0.05) and 41/85 females (48%, p = 0.22) in non-participants. Bubble-echocardiography was suggestive of shunt in 10/45 (22%) participants and PAVM was subsequently confirmed by computed tomography in one patient with grade 1 shunting. The corresponding prevalence of PAVM was 2% (95% confidence interval 0.06-11.8) amongst all examined participants. Another 9/45 (20%) were diagnosed with patent in persistent foramen ovale (n = 8) or atrial septum defect (n = 1), which is comparable with the overall prevalence of 25% amongst adults in the Danish background population. CONCLUSIONS: Undiagnosed PAVM amongst adult survivors of cryptogenic bacterial brain abscess is rare but may be considered in select patients. The prevalence of cardiac right-to-left shunts amongst brain abscess patients corresponds to the prevalence in the general population.

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A 42-year-old man was referred to our hospital because of anemia. The patient underwent gastroscopy and colonoscopy, but no bleeding site was detected. Abdominal contrast-enhanced computed tomography (CT) showed vascular dilatation along the wall of the small intestine. Small bowel capsule endoscopy and antegrade double-balloon endoscopy (DBE) were performed, and the patient was diagnosed with a small intestinal arteriovenous malformation (AVM). The AVM was clipped using DBE. After clipping, abdominal contrast-enhanced CT and small bowel angiography revealed the disappearance of the AVM. DBE may be a viable therapeutic option, helping avoid surgery and its associated risks.

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RATIONALE: Renal arteriovenous malformations are rare vascular morphological anomalies that can be classified as congenital, idiopathic and acquired, of which congenital renal arteriovenous malformations are the most common. This disease is a rare cause of hematuria. In this case report, we report the diagnosis and treatment of a patient with renal arteriovenous malformation. We also review the symptoms, diagnosis and treatment of renal arteriovenous malformations in the published literature. PATIENT CONCERNS: A 35-year-old female patient presented to a local hospital with right-sided lumbar abdominal pain with hematuria for 2 days. Physical examination showed percussion pain in the right renal area. Laboratory tests such as routine blood and blood biochemistry did not show any significant abnormalities when the patient entered the hospital. Considering the patient's medical history, a urological computed tomography scan showed blood accumulation in the right renal pelvis, upper middle ureter and bladder. Subsequently, routine blood tests showed that the patient's red blood cells and hemoglobin continued to decrease. An emergency renal arteriogram was performed, which showed a tortuous right upper renal pole branch artery and multiple thickened veins communicating with it. DIAGNOSIS: This patient was diagnosed with cirsoid renal arteriovenous malformation. INTERVENTIONS: Renal artery embolization was performed immediately after the renal arteriogram was performed on the patient. OUTCOMES: On review of the angiogram, the tortuous right upper renal pole branch artery was found to be obstructed, and the thickened vein disappeared, and the renal vein was normally visualized in due course. On the third postoperative day, the patient was free of hematuria. Physical examination showed no percussion pain in the renal area. The patient healed and was discharged. A 1-year follow-up was performed and the patient gave feedback that she no longer had symptoms such as back pain and hematuria in her daily life. LESSONS: This case illustrates that early use of vascular interventions is an important method for the diagnosis and treatment of cirsoid renal arteriovenous malformations.

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OBJECTIVE: To assess the utility of the Curaçao criteria by age over time in children with hereditary hemorrhagic telangiectasia (HHT). STUDY DESIGN: This was a single-center, retrospective analysis of patients attending the HHT clinic at the Hospital for Sick Children (Toronto, Canada) between 2000 and 2019. The evaluation of the Curaçao criteria was completed during initial and follow-up visits. Screening for pulmonary and brain arteriovenous malformations was completed at 5 yearly intervals. RESULTS: A total of 116 patients with genetic confirmation of HHT were included in the analysis. At initial screening at a median (IQR) age of 8.4 (2.8, 12.9) years, 41% met criteria for a definite clinical diagnosis (≥3 criteria). In children <6 years at presentation, only 23% fulfilled at least 3 criteria initially. In longitudinal follow-up, 63% reached a definite clinical diagnosis, with a median (IQR) follow-up duration of 5.2 (3.2, 7.9) years (P = .005). Specifically, more patients met the epistaxis and telangiectasia criteria at last visit compared with initial (79% vs 60%; P = .006; 47% vs 30%; P = .02) but not for the arteriovenous malformation criterion (59% vs 57%; P = .65). CONCLUSIONS: In the pediatric population, most patients do not meet definite clinical criteria of HHT at initial presentation. Although the number of diagnostic criteria met increased over time, mainly due to new onset of epistaxis and telangiectasia, accuracy remained low during follow-up visits. Relying solely on clinical criteria may lead to underdiagnosis of HHT in children.

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Gastrointestinal arteriovenous malformations (AVMs) are a rare disease. Sigmoid-anorectal AVM has only been reported in a few cases. The condition is usually detected when patients have gastrointestinal bleeding complications. The diagnosis and treatment of colorectal AVMs are still challenging. This paper presents a case of an Asian 32-year-old female patient admitted to hospital because of lower gastrointestinal bleeding lasting 17 years. The patient was diagnosed with sigmoid-rectal arteriovenous malformation and failed with other medical treatments. The damaged gastrointestinal tract was removed by a laparoscopic low anterior resection. The results were positive after a three-month follow-up; the bleeding was resolved, and the anal sphincter function was intact. Laparoscopic low anterior resection is a safe, less invasive, and effective approach for managing patients with digestive tract bleeding due to extensive colorectal AVM and preservation of the anal sphincter.

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Pulmonary arteriovenous malformations (PAVMs) are rare and most often identified in patients with hereditary hemorrhagic telangiectasia (HHT). We describe a patient with severe hypoxemia and orthodeoxia with imaging findings consistent with PAVMs. Resected lung pathologic findings confirmed the presence of numerous microscopic vascular abnormalities within the right lower lobe that was consistent with diffuse pulmonary arteriovenous shunts. Family history was negative for HHT but was positive for pulmonary arterial hypertension (PAH) in two second-degree relatives. A vascular malformation gene panel was negative for genes that commonly are associated with HHT but identified a pathogenic variant in the gene encoding bone morphogenetic protein receptor-2 (BMPR2 p.Cys123∗). Pathogenic variants in BMPR2 are a well-known cause of hereditary PAH; there have been several reports to date of patients with PAVMs and PAH. However, this is the first patient to be reported with a pathogenic variant in BMPR2 to have PAVMs in isolation.

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Gastrointestinal bleeding that originates in the small intestine is often difficult to diagnose. Bleeding from a small intestinal arteriovenous malformation (AVM) is rare, with congenital AVMs more commonly located in the rectum or sigmoid. There is a relative paucity of cases reported in the literature. In the gastrointestinal tract, it can cause acute and chronic bleeding, which can be fatal. Although the incidence of small bowel AVMs is quite low, such lesions can be identified as the bleeding source in patients with obscure gastrointestinal bleeding (OGIB) harbouring severe, transfusion-dependent anaemia. It can be exceedingly difficult to localise and diagnose gastrointestinal tract bleeding, particularly in cases of occult small bowel AVMs. CT angiography and capsule endoscopy can help to establish the diagnosis. Laparoscopy is an appropriate and beneficial treatment modality for small bowel resection. The authors present the case of a primigravida woman in her late 20s diagnosed with a symptomatic transfusion-dependent anaemia during her pregnancy. She developed OGIB and despite no history of chronic liver disease became encephalopathic. Due to her physical deterioration and uncertain diagnosis, her caesarean section was performed at 36+6 weeks to expedite investigations and treatment. She was diagnosed with a jejunal AVM and underwent coiled embolisation of her superior mesenteric artery. She became haemodynamically unstable and underwent a laparotomy and small bowel resection. A full non-invasive liver screen was negative, however, her MRI liver described multiple focal nodular hyperplasia (FNH) lesions raising the possibility of FNH syndrome in the context of a previous AVM malformation. A prompt stepwise, multimodality diagnostic approach is required to prevent patient morbidity and mortality.

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