Immunohistochemical Expression of Lymphatic Endothelial Markers in Blue Rubber Bleb Nevus Syndrome

INTRODUCTION

Blue rubber bleb nevus syndrome (BRBNS) is an uncommon vascular anomaly characterized by multifocal cutaneous, visceral, and other soft tissue or solid organ venous malformations. We observed that BRBNS lesions express immunohistochemical markers of lymphatic differentiation.

METHODS

BRBNS histopathologic specimens assessed at our institution during the past 27 years were reviewed. Slides from 19 BRBNS lesions were selected from 14 patients (9 cutaneous, 9 gastrointestinal, and 1 hepatic). We recorded the involved anatomical compartments and presence/absence of thrombi or vascular smooth muscle. Immunohistochemical endothelial expression of PROX1 (nuclear) and D2-40 (membranous/cytoplasmic) was evaluated semi-quantitatively.

RESULTS

Endothelial PROX1 immunopositivity was noted in all specimens; the majority (89.5%) demonstrated staining in more than 10% of cells. D2-40 immunopositivity was present in one-third (33%) of cutaneous lesions and only 1 gastrointestinal lesion.

CONCLUSION

Endothelial cells in BRBNS almost always express 1 or more immunohistochemical markers of lymphatic differentiation.

Spectrum of lymphatic anomalies in patients with RASA1-related CM-AVM

BACKGROUND

Capillary malformation-arteriovenous malformation (CM-AVM) is characterized by multifocal fast-flow capillary malformations, sometimes with arteriovenous malformations/fistulas, skeletal/soft tissue overgrowth, telangiectasias, or Bier spots. Lymphatic abnormalities are infrequently reported. We describe seven patients with CM-AVM and lymphatic anomalies.

METHODS

Following IRB approval, we identified patients with CM-AVM and lymphatic anomalies seen at the Vascular Anomalies Center at Boston Children's Hospital from 2003 to 2023. We retrospectively reviewed records for clinical, genetic, laboratory, and imaging findings.

RESULTS

We found seven patients with CM-AVM and lymphatic abnormalities. Five patients were diagnosed prenatally: four with pleural effusions (including one suspected chylothorax) and one with ascites. Pleural effusions resolved after neonatal drainage in three patients and fetal thoracentesis in the fourth; however, fluid rapidly reaccumulated in this fetus causing hydrops. Ascites resolved after neonatal paracentesis, recurred at 2 months, and spontaneously resolved at 5 years; magnetic resonance lymphangiography for recurrence at age 19 years suggested a central conducting lymphatic anomaly (CCLA), and at age 20 years a right spermatic cord/scrotal lymphatic malformation (LM) was detected. Chylous pericardial effusion presented in a sixth patient at 2 months and disappeared after pericardiocentesis. A seventh patient was diagnosed with a left lower extremity LM at 16 months. Six patients underwent genetic testing, and all had RASA1 mutation. RASA1 variant was novel in three patients (c.1495delinsCTACC, c.434_451delinsA, c.2648del), previously reported in two (c.2603+1G>A, c.475_476del), and unavailable in another. Median follow-up age was 5.8 years (4 months-20 years).

CONCLUSION

CM-AVM may be associated with lymphatic anomalies, including pericardial/pleural effusions, ascites, CCLA, and LM.

Surgical Resection of Vulvar Labial Venous Malformations: A Single Center Experience

BACKGROUND

Venous malformations (VMs) involving the vulva are rare but often cause debilitating pain, aesthetic concern, and functional impairment. Treatment with medical therapy, sclerotherapy, operative resection, or a combination thereof may be considered. The optimal therapeutic approach remains unclear. We report our experience resecting labial VMs in a large cohort of patients.

METHODS

A retrospective review of patients who underwent partial or complete resection of a labial VM was conducted.

RESULTS

Thirty-one patients underwent forty-three resections of vulvar VMs between 1998 and 2022. Physical examination and imaging demonstrated: 16% of patients had focal labial lesions, 6% had multifocal labial lesions, and 77% had extensive labial lesions. Indications for intervention included pain (83%), appearance (21%), functional impairment (17%), bleeding (10%), and cellulitis (7%). Sixty-one percent of patients underwent a single resection, 13% multiple partial resections, and 26% a combination of sclerotherapy and operative resection(s). Median age was 16.3 years at first operation. All patients requiring multiple operations had extensive VMs. Median blood loss was 200 mL. Postoperative complications included wound infection/dehiscence (14%), hematoma (2%), and urinary tract infection (2%). The median follow-up assessment was 14 months: 88% of patients had no complaints and 3 patients were experiencing recurrent discomfort.

CONCLUSIONS

Surgical resection is a safe and effective approach to treating vulvar labial VMs. Patients with focal or multifocal VMs can be successfully treated with a single resection, whereas patients with an extensive VM may require multiple partial resections or combined sclerotherapy and resection(s) to achieve long-term control.

TYPE OF STUDY

Retrospective Study.

LEVEL OF EVIDENCE

IV.

Kaposiform Lymphangiomatosis: Pathologic Aspects in 43 Patients

Kaposiform lymphangiomatosis is an uncommon generalized lymphatic anomaly with distinctive clinical, radiologic, histopathologic, and molecular findings. Herein, we document the pathology in 43 patients evaluated by the Boston Children's Hospital Vascular Anomalies Center from 1999 to 2020. The most frequent presentations were respiratory difficulty, hemostatic abnormalities, and a soft tissue mass. Imaging commonly revealed involvement of some combination of mediastinal, pulmonary, pleural, and pericardial compartments and most often included spleen and skeleton. Histopathology was characterized by dilated, redundant, and abnormally configured lymphatic channels typically accompanied by dispersed clusters of variably canalized, and often hemosiderotic, spindled lymphatic endothelial cells that were immunopositive for D2-40, PROX1, and CD31. An activating lesional NRAS variant was documented in 9 of 10 patients. The clinical course was typically aggressive, marked by hemorrhage, thrombocytopenia, diminished fibrinogen levels, and a mortality rate of 21%.

Cerebrospinal fluid leak in epidural venous malformations and blue rubber bleb nevus syndrome

OBJECTIVE

Clinical manifestations of blue rubber bleb nevus syndrome (BRBNS) and multifocal venous malformation (MVM) vary depending on the location of the lesions. The aim of this study was to assess the risk of developing CSF leaks in patients with epidural venous malformations (VMs).

METHODS

The authors retrospectively investigated the relationship between the development of a CSF leak and the presence of epidural VMs.

RESULTS

Nine patients (5 females) had epidural VMs and presentation that was confirmatory or suggestive of a CSF leak: 4 had BRBNS, 4 had MVMs, and 1 had a solitary VM. Of 66 patients with BRBNS, clinical and imaging features of CSF leak were noted in 3 (4.5%) with epidural VMs at the age of 11-44 years. A fourth patient had suggestive symptoms without imaging confirmation. An epidural blood patch was ineffective in 2 patients, both with more than one source of leakage, requiring surgical repair or decompression. Symptomatic downward displacement of the cerebellar tonsils was noted in 3 patients with MVM and 1 with a solitary VM; 3 required surgical decompression.

CONCLUSIONS

These findings suggest an increased risk of CSF leak in patients with epidural VM, including BRBNS, MVMs, and solitary VMs. Awareness of the association between epidural VM and CSF leakage may facilitate earlier diagnosis and therapeutic intervention.

Early Experiences Designing a Scalable COVID-19 Reusable Elastomeric Respirator

The COVID-19 pandemic created an unprecedented shortage of personal protective equipment (PPE) for healthcare workers - especially respirators. In response to a lack of commercial respirator equipment, a multidisciplinary prototyping hackathon was held and the key components required to develop an inexpensive, scalable "COVID-19 Reusable Elastomeric Respirator" (RER-19) were identified. Available hospital supplies were assessed based on their published technical specifications to meet each of the key component requirements. The fully assembled prototype was then validated through user testing, and volunteers underwent standard fit testing with cardiopulmonary monitoring while wearing the RER-19 in a small pilot study. Multiple social media platforms were then used to disseminate educational information on respirator assembly, use, and maintenance. Here we present our institution's initial experience with prototyping to meet a specific healthcare challenge, in combination with prompt dissemination of information to educate and empower healthcare workers in the face of a critical PPE shortage during an unprecedented and evolving pandemic.

Verrucous Venous Malformation-Subcutaneous Variant

BACKGROUND

Verrucous venous malformation (VVM), previously called "verrucous hemangioma," typically involves the dermis and the subcutaneous fat. We have encountered patients with VVM confined to the hypodermis.

MATERIALS AND METHODS

During a nearly 20-year period, 13 patients, aged 2-17 years, presented with a subcutaneous mass in the limb without clinically obvious epidermal alterations. Consequently, operative excisions did not include the skin.

RESULTS

Histopathologically, the specimens were composed of blood-filled channels with morphologic characteristics of capillaries and veins that infiltrated adipose tissue. Aggregates often formed nodules with variable fibrosis and a component of large and radially oriented vessels. A diagnosis of VVM was supported by endothelial immunopositivity for GLUT-1 (25%-75% immunopositive channels in 16/16 specimens); D2-40 (1%-25% channels in 14/15 specimens); and Prox-1 (1%-50% of channels in 14/16 specimens). A MAP3K3 mutation was identified by droplet digital PCR in 3 of the 6 specimens.

CONCLUSIONS

Diagnosis of VVM in this uncommon location is challenging because of absence of epidermal changes and lack of dermal involvement. Imaging is not pathognomonic, and mimickers are many. Appropriate immunohistochemical stains and molecular analysis contribute to the correct diagnosis.

Parkes Weber syndrome with lymphedema caused by a somatic KRAS variant

Parkes Weber syndrome is a vascular malformation overgrowth condition typically involving the legs. Its main features are diffuse arteriovenous fistulas and enlargement of the limb. The condition has been associated with pathogenic germline variants in RASA1 and EPHB4. We report two individuals with Parkes Weber syndrome of the leg and primary lymphedema containing a somatic KRAS variant (NM_004985.5:c.35G > A; p.Gly12Asp). KRAS variants, which cause somatic intracranial and extracranial arteriovenous malformations, also result in Parkes Weber syndrome with lymphatic malformations.

The use of the internal mammary vein for central venous access

PURPOSE

To describe the use of the internal mammary vein as an alternative access for central venous catheters.

METHODS

We performed a retrospective review of patients who underwent placement of central venous catheters via the internal mammary vein. Patient demographics, indication for venous access, technical success, catheter type, dwell time and indication for exchange or removal were recorded.

RESULTS

Placement of central venous catheters via the internal mammary vein was attempted in 11 patients including 8 children (4 males, mean age 5.7 years) and 3 adults. The most common indication was parenteral nutrition in patients with intestinal failure (7/11). Initial needle access of the vein was successful in all patients. Catheter placement was successful in 9 and unsuccessful in 2 patients due to occlusion of the superior vena cava. There were no immediate complications. A total of 20 catheters of various sizes (3-14.5 French) and lengths (8-23 cm) were either placed (n = 12) or exchanged (n = 8). The most common indications for catheter exchange were poor function and malposition (7/8). Four catheters were removed for infection and 4 were accidentally removed. The mean dwell time was 141 days (range 0-963 days) per catheter for a total of 2829 catheter days. The total mean dwell time per patient, including primarily placed and exchanged catheters, was 314 days (range 5-963 days).

CONCLUSIONS

The internal mammary vein may provide a safe alternative route for patients who have lost their traditional access veins.

Congenital Disseminated Pyogenic Granuloma: Characterization of an Aggressive Multisystemic Disorder

OBJECTIVE

To describe the clinical, radiologic, and histopathologic features of "congenital disseminated pyogenic granuloma" involving various organs with high morbidity related to cerebral hemorrhagic involvement.

STUDY DESIGN

We searched the database of the Vascular Anomalies Center at Boston Children's Hospital from 1999 to 2019 for patients diagnosed as having multiple vascular lesions, visceral vascular tumors, congenital hemangiomatosis, multiple pyogenic granulomas, or multiple vascular lesions without a definite diagnosis. A retrospective review of the medical records, photographs, histopathologic, and imaging studies was performed. Only patients with imaging studies and histopathologic diagnosis of pyogenic granuloma were included.

RESULTS

Eight children (5 male, 3 female) had congenital multifocal cutaneous vascular tumors. Lesions also were found in the brain (n = 7), liver (n = 4), spleen (n = 3), muscles (n = 4), bone (n = 3), retroperitoneum (n = 3), and intestine/mesentery (n = 2). Less commonly affected were the spinal cord, lungs, kidneys, pancreas, and adrenal gland (n = 1 each). The mean follow-up period was 21.8 months. The cerebral and visceral lesions were hemorrhagic with severe neurologic sequelae. The histopathologic diagnosis was pyogenic granuloma with prominent areas of hemorrhage and necrosis. The endothelial cells had enlarged nuclei, pale cytoplasm and were immunopositive for CD31 and negative for D2-40 and glucose transporter 1.

CONCLUSIONS

Congenital disseminated pyogenic granuloma is a distinct multisystemic aggressive disorder that primarily affects the skin, brain, visceral organs, and musculoskeletal system. Differentiation of this entity from other multiple cutaneous vascular lesions is critical because of possible cerebral hemorrhagic involvement.

Arteriovenous malformation phenotype resembling congenital hemangioma contains KRAS mutations

Extracranial arteriovenous malformation (AVM) is most commonly caused by a somatic mutation in MAP2K1. We report two patients with vascular anomalies that had an unclear clinical diagnosis most consistent with either an AVM or congenital hemangioma. Lesions were cutaneous, reddish-purple with telangiectasias, present at birth, and had defined borders. Histopathology indicated AVM and both lesions contained somatic KRAS mutations. A rare AVM phenotype exists that shares clinical features with congenital hemangioma.

Fibroadipose Vascular Anomaly in the Upper Extremity: A Distinct Entity With Characteristic Clinical, Radiological, and Histopathological Findings

PURPOSE

Fibroadipose vascular anomaly (FAVA) is an intramuscular vascular malformation that has been recently described as a distinct clinical entity. The clinical, radiological, and histopathological characteristics of FAVA in the upper extremity are reviewed.

METHODS

This was a retrospective case series of upper-extremity FAVA lesions.

RESULTS

We reviewed 19 patients with FAVA of the upper limb. Pain, stiffness, swelling, and flexion contractures were the most common presentations. Except for one lesion confined to the hand, all lesions either presented with or developed a contracture within 10 years. Ten patients underwent surgical debulking. Six required tendon transfer reconstruction and 3 necessitated a free functional muscle transfer.

CONCLUSIONS

Fibroadipose vascular anomaly in the upper extremity requires an accurate diagnosis and may benefit from early referral to a multidisciplinary vascular anomaly center with experienced hand surgeons. Compression garments, propranolol, and sclerotherapy seem to be ineffective. Surgical resection focused on symptomatic regions with appropriate reconstruction may have benefit in salvage of limbs with compromised function.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Clinical and radiological characteristics of patients with retroperitoneal infantile hemangiomas

BACKGROUND

Infantile hemangiomas (IHs) are the most common tumors of infancy. The objective was to identify clinical and radiological patterns in patients with retroperitoneal IHs.

METHODS

We reviewed patients from our Vascular Anomalies Center database with IHs and abdominal imaging presenting from 1999 to 2017 to identify retroperitoneal involvement.

RESULTS

Eleven patients (10 females, one male) with retroperitoneal IHs were found. Cutaneous IHs were present in eight patients (five segmental (45%), three multifocal (27%)) and absent in 1 (9%). Segmental hemangiomas involved the face in 2/5 (40%) and lower body in 3/5 (60%). The most common symptoms were dyspnea (n = 4), hematochezia (n = 3), and/or ulceration (n = 2). Three patients were asymptomatic. Involved retroperitoneal organs included the duodenum (n = 4), pancreas (n = 3), and adrenal glands (n = 1). Non-retroperitoneal organ involvement included the liver (n = 5), non-duodenal small intestine (n = 4), and large intestine (n = 3). Perivascular retroperitoneal hemangiomas were seen in 6/11 patients (55%), most commonly surrounding the aorta (n = 5), iliac vessels (n = 2), and/or inferior vena cava (n = 2). Three of 11 patients (27%) had LUMBAR based on a segmental, sacral hemangioma with tethered cord or anorectal malformation. Follow-up information was available in 6/11 patients (55%): 5 symptomatically improved with treatment (propranolol, corticosteroids, and/or vincristine), while one succumbed from extensive hepatic involvement.

CONCLUSION

Retroperitoneal IHs are rare and tend to involve organs or surround vessels. Associated cutaneous IHs, if present, lack anatomical predilection and may be segmental or multifocal.

Lymphaticovenous bypass of the thoracic duct for the treatment of chylous leak in central conducting lymphatic anomalies

BACKGROUND

Central conducting lymphatic anomalies (CCLA) may cause chylous leaks and protein-losing enteropathy (PLE) owing to dysfunction of the central lymphatic channels. Most of the treatment strategies for these conditions are palliative and provide transient improvement.

METHODS

We treated 14 patients with intractable chylous leak and/or PLE using a novel technique of lymphaticovenous bypass of the terminal portion of the thoracic duct. Chylous leaks occurred in multiple different anatomic sites. All patients had CCLA and failure of thoracic duct emptying demonstrated by preoperative intranodal lymphangiography.

RESULTS

Five patients had complete resolution of symptoms, and two patients had partial improvement. There were no major complications. Of 5 patients with PLE, only one improved after lymphaticovenous bypass. Repeat traditional lymphangiography was performed in 4 patients who did not improve, demonstrating patency of the bypass in all cases with persistent sluggish drainage. One patient had repeat MR lymphangiography that did not show the thoracic duct well.

CONCLUSIONS

Bypass of the terminal thoracic duct is a novel procedure that offers improvement and a chance of cure for some patients with devastating manifestations of CCLA who lack other effective therapeutic options.

LEVEL OF EVIDENCE

IV.

Thoracoscopic esophagomyotomy for achalasia in the pediatric population: A retrospective cohort study

BACKGROUND/PURPOSE

Achalasia is an extremely rare disease in children (0.1 per 100,000 individuals). Standard treatments for this include pneumatic dilation and esophagomyotomy. Minimally invasive esophagomyotomies have increasingly been used owing to improved postoperative pain and length of stay. We describe our experience with thoracoscopic esophagomyotomy in this population.

METHODS

This is a retrospective cohort study of all patients at our institution who underwent thoracoscopic esophagomyotomy for achalasia from 1995 to 2016. We used endoscopic guidance during all procedures. No fundoplication was performed.

RESULTS

Thirty-one patients were included in this study. Thirteen patients underwent pneumatic dilations prior to their operation with a median of 3 dilations. Two patients had a mucosal injury during the case. There were no conversions to an open procedure. Median length of stay was 2 days. After the procedure, 97% of patients had initial symptom relief. Eight patients (26%) required postoperative pneumatic dilations for recurrent symptoms; there was a greater chance of this (OR 8.5) if they had a preoperative dilation. No patients required a fundoplication for reflux postoperatively.

CONCLUSIONS

Thoracoscopic esophagomyotomy is a safe and effective procedure for achalasia in the pediatric population. It should be considered as an alternative to the laparoscopic approach for these patients.

LEVEL OF EVIDENCE

IV.

A somatic activating NRAS variant associated with kaposiform lymphangiomatosis

Purpose:

Kaposiform lymphangiomatosis (KLA) is a rare, frequently aggressive, systemic disorder of the lymphatic vasculature, occurring primarily in children. Even with multimodal treatments, KLA has a poor prognosis and high mortality rate secondary to coagulopathy, effusions and systemic involvement. We hypothesized that, as has recently been found for other vascular anomalies, KLA may be caused by somatic mosaic variants affecting vascular development.

Methods:

We performed exome sequencing of tumor samples from five individuals with KLA, along with samples from uninvolved control tissue in three of the five. We used digital PCR (dPCR) to validate the exome findings and to screen KLA samples from six other individuals.

Results:

We identified a somatic activating NRAS variant (c.182A>G, p.Q61R) in lesional tissue from 10/11 individuals, at levels ranging from 1–28%, that was absent from the tested control tissues.

Conclusion:

The activating NRAS p.Q61R variant is a known ‘hotspot’ variant, frequently identified in several types of human cancer, especially melanoma. KLA, therefore, joins a growing group of vascular malformations and tumors caused by somatic activating variants in the RAS/PI3K/mTOR signalling pathways. This discovery will expand treatment options for these high risk patients as there is potential for use of targeted RAS pathway inhibitors.

Guidance Document for Hepatic Hemangioma (Infantile and Congenital) Evaluation and Monitoring

OBJECTIVE

To define the types of hepatic hemangiomas using the updated International Society for the Study of Vascular Anomalies classification and to create a set of guidelines for their diagnostic evaluation and monitoring.

STUDY DESIGN

We used a rigorous, transparent consensus protocol defined by an approved methodology, with input from multiple pediatric experts in vascular anomalies from hematology-oncology, surgery, pathology, radiology, and gastroenterology.

RESULTS

In the first section, we define the subtypes of hepatic hemangiomas based on the clinical course, histology, and radiologic characteristics. We recommend against using the term "hemangioma" for any vascular malformations affecting the liver or any hypervascular tumors that are not characterized by the approved definitions. We recommend against using the term "hemangioendothelioma" for infantile or congenital hemangioma. The following 2 sections dedicated to infantile hepatic hemangioma and to congenital hepatic hemangioma individually describe these subtypes in further detail, including complications to be considered during monitoring and respectively recommended screening evaluations.

CONCLUSIONS

Although institutional variations may exist for specific clinical details, a clear understanding of the diagnosis of hepatic hemangiomas affecting children and the possible complications that require screening during the monitoring period should be standard. As children with hepatic hemangiomas are managed by different medical and surgical specialties, we offer an expert opinion multidisciplinary consensus based on current literature and on data extracted from the liver hemangioma registry.

Pulmonary thromboembolic events in patients with congenital lipomatous overgrowth, vascular malformations, epidermal nevi, and spinal/skeletal abnormalities and Klippel-Trénaunay syndrome

OBJECTIVE

Patients with Klippel-Trénaunay syndrome (KTS) and congenital lipomatous overgrowth, vascular malformations, epidermal nevi, and spinal/skeletal abnormalities (CLOVES) syndrome have central phlebectasia and enlarged persistent embryonic veins that are often incompetent and prone to thromboembolism. The purpose of the study was to determine the presence of phlebectasia and the incidence of symptomatic pulmonary embolism (PE).

METHODS

A retrospective review was conducted of patients referred to the Vascular Anomalies Center at our institution during a 21-year period who were diagnosed with KTS and CLOVES syndrome. Of these, the patients who had PE were screened for thromboembolic risk factors in addition to phlebectasia and the presence of persistent embryonic veins. Treatment outcomes following subsequent endovascular and medical therapies were reported.

RESULTS

A total of 12 KTS patients of 96 (12.5%) and 10 CLOVES syndrome patients of 110 (9%) suffered PE. Fourteen patients (64%) developed PE after surgery or sclerotherapy. All of the patients had abnormally dilated central or persistent embryonic veins; 20 patients were treated with anticoagulation (1 died at the time of presentation, and no information was available for 1) after PE, and 14 (66%) patients underwent subsequent endovascular treatment. Five patients developed recurrent PE despite anticoagulation. Two of the patients died of PE. No patients treated with endovascular closure of dilated veins had subsequent evidence of PE.

CONCLUSIONS

Patients with KTS and CLOVES syndrome are at high risk for PE, particularly in the postoperative period.

Preoperative Embolization of Venous Malformations Using n-Butyl Cyanoacrylate

Purpose:

The purpose of this study was to evaluate the safety and efficacy of preoperative percutaneous n-butyl cyanoacrylate (nBCA) embolization of venous malformations in children.

Material and Methods:

Clinical data were retrospectively reviewed in children who underwent embolization using nBCA followed by resection of venous malformations.

Results:

A total of 17 embolizations were performed in 14 patients (9 females, mean age: 5.5 years; median age: 3 years; range 0.1-16 years). The venous malformations involved the lower extremity and the knee joint (n = 7), the trunk (n = 4), head and neck (n = 2), and hand (n = 1). n-Butyl cyanoacrylate was diluted with iodized oil at a ratio of 1:3 to 1:5. The mean and median volume of nBCA per procedure were 2.1 and 2 mL, respectively (range: 0.5-8 mL). There were no complications associated with the procedures. The mean and median time between final embolization and resection were 3.6 and 2 days, respectively. All children underwent successful resection of the symptomatic lesions. The estimated mean and median blood loss were 75 and 50 mL, respectively (range: 5-350 mL). The postprocedure course was uneventful, the days to discharge ranged between 1 and 6 days (mean 3 days).

Conclusion:

Initial results suggest that preoperative percutaneous n-butyl cyanoacrylate embolization of venous malformations is safe and effective in children, with the potential for minimizing blood loss and inpatient stay.

Internal venous anomalies in patients with a genital venous malformation

BACKGROUND

Cutaneous venous malformation (VM) can be associated with internal vascular anomalies. Our objective was to investigate the frequency of internal vascular anomalies in patients with an isolated genital venous malformation to assess the utility of screening for internal findings.

METHODS

We retrospectively reviewed our Vascular Anomalies Center database for patients with a focal genital venous malformation presenting between 1999 and 2016. Abdominal and pelvic imaging reports were reviewed for internal vascular anomalies. Endoscopy reports were also reviewed when available.

RESULTS

A focal genital venous malformation was found in 22 patients (14 female, 8 male). Ten (45%) had a venous malformation of at least one internal structure, most commonly the pelvic floor (n = 6), colon (n = 5), urethra (n = 4), and/or bladder (n = 3). Eight experienced hematuria, hematochezia, and/or rectorrhagia secondary to their internal venous malformation. In patients with internal venous malformations, the mean age of symptom presentation was 7.3 years (range 1-22 years). Two patients had malformed inferior mesenteric and portal veins visible using ultrasonography and magnetic resonance imaging. They required surgical intervention to prevent thrombosis and decrease urogenital and gastrointestinal bleeding.

CONCLUSION

Nearly half of our patients with a focal genital venous malformation had internal venous anomalies. Physicians should suspect urogenital or gastrointestinal venous malformations in patients with a focal genital venous malformation, especially if they develop hematuria, hematochezia, or rectorrhagia. Significant mesenteric venous trunk anomalies can also occur. Because these require surgical intervention, early recognition is important. We recommend that all patients with a focal genital venous malformation undergo abdominal and pelvic ultrasound to evaluate for internal venous anomalies.

Sonographic screening for Wilms tumor in children with CLOVES syndrome

BACKGROUND

CLOVES syndrome is associated with somatic mosaic PIK3CA mutations and characterized by congenital lipomatous overgrowth, vascular malformations, epidermal nevi, and skeletal anomalies. Wilms tumor (WT) is a malignant embryonal renal neoplasm associated with hemihypertrophy and certain overgrowth disorders. After identifying WT in a child with CLOVES, we questioned whether ultrasonographic screening was necessary in these patients.

METHODS

We retrospectively reviewed patients with CLOVES syndrome in our Vascular Anomalies Center at Boston Children's Hospital between 1998 and 2016 to identify those who developed WT. A PubMed literature search was also conducted to find other patients with both conditions.

RESULTS

A total of 122 patients with CLOVES syndrome were found in our database (mean age 7.7 years, range 0-53 years). Four patients developed WT; all were diagnosed by 2 years of age. The incidence of WT in our CLOVES patient population (3.3%) was significantly greater than the incidence of WT in the general population (1/10,000) (P < 0.001). Four additional patients with WT and CLOVES syndrome were identified in our literature review.

CONCLUSION

Patients with CLOVES syndrome have an increased risk of WT. Given the benefits of early detection and treatment, children with CLOVES syndrome should be considered for quarterly abdominal ultrasonography until age 7 years. Screening may be most beneficial for patients under 3 years of age.

Late sequelae and long-term outcomes of vascular anomalies

Vascular anomalies are classified as tumors and malformations depending on their clinical characteristics, pathological diagnosis and recent genomic information. Diagnosis can still be challenging because of the heterogeneity of clinical presentation. Thus, the best care is provided by an interdisciplinary team of specialists. An updated classification system has helped provide more consistent terminology with the addition of new diagnoses and genomic discovery. Historically, treatment of vascular anomalies was primarily surgical and or interventional with limited medical therapies. The field of vascular anomalies lacked prospective clinical trials in both medical treatments as well as surgical and interventional therapeutic options. Recent interdisciplinary collaboration has led to collaborative studies in which short- and long-term outcomes are being prospectively evaluated. Specifically, discoveries of pharmacologic agents effective in treating vascular anomalies have broadened our medical therapeutic options, which has led to innovative approaches in combined treatment of vascular anomalies and has stressed the need to prospectively assess long-term outcomes and sequelae for these patients which has been lacking in this field.

Wilms tumor screening in diffuse capillary malformation with overgrowth and macrocephaly-capillary malformation: A retrospective study

BACKGROUND

CLOVES (congenital lipomatous overgrowth, vascular malformations, epidermal nevi, and skeletal anomalies) syndrome is associated with regional bony and/or soft tissue overgrowth, capillary malformation, and an increased risk for Wilms tumor.

OBJECTIVE

To evaluate the frequency of Wilms tumor in patients with 2 similar conditions: diffuse capillary malformation with overgrowth (DCMO) and macrocephaly-capillary malformation (M-CM).

METHODS

Culling our Vascular Anomalies Center database, we retrospectively reviewed patients in whom DCMO and M-CM had been diagnosed and who were evaluated between 1998 and 2016 for possible development of Wilms tumor. Patients younger than 8 years of age at their last visit and not seen in more than 2 years were contacted for follow-up.

RESULTS

The study comprised 89 patients: 67 with DCMO, 17 with M-CM, and 5 with an indeterminate diagnosis. No case of Wilms tumor was found in these groups.

LIMITATIONS

Some patients were younger than 8 years of age at last follow-up visit and the sample size was small.

CONCLUSION

Patients with DCMO do not appear to be at increased risk for Wilms tumor. Screening is probably unnecessary in DCMO unless there is associated hemihypertrophy. Although there were no cases in our cohort, there are 2 reports of M-CM associated with Wilms tumor in the literature.

Somatic MAP2K1 Mutations Are Associated with Extracranial Arteriovenous Malformation

Arteriovenous malformation (AVM) is a fast-flow, congenital vascular anomaly that may arise anywhere in the body. AVMs typically progress, causing destruction of surrounding tissue and, sometimes, cardiac overload. AVMs are difficult to control; they often re-expand after embolization or resection, and pharmacologic therapy is unavailable. We studied extracranial AVMs in order to identify their biological basis. We performed whole-exome sequencing (WES) and whole-genome sequencing (WGS) on AVM tissue from affected individuals. Endothelial cells were separated from non-endothelial cells by immune-affinity purification. We used droplet digital PCR (ddPCR) to confirm mutations found by WES and WGS, to determine whether mutant alleles were enriched in endothelial or non-endothelial cells, and to screen additional AVM specimens. In seven of ten specimens, WES and WGS detected and ddPCR confirmed somatic mutations in mitogen activated protein kinase kinase 1 (MAP2K1), the gene that encodes MAP-extracellular signal-regulated kinase 1 (MEK1). Mutant alleles were enriched in endothelial cells and were not present in blood or saliva. 9 of 15 additional AVM specimens contained mutant MAP2K1 alleles. Mutations were missense or small in-frame deletions that affect amino acid residues within or adjacent to the protein's negative regulatory domain. Several of these mutations have been found in cancers and shown to increase MEK1 activity. In summary, somatic mutations in MAP2K1 are a common cause of extracranial AVM. The likely mechanism is endothelial cell dysfunction due to increased MEK1 activity. MEK1 inhibitors, which are approved to treat several forms of cancer, are potential therapeutic agents for individuals with extracranial AVM.

Umbilical Venous Catheter Malposition Is Associated with Necrotizing Enterocolitis in Premature Infants

OBJECTIVE

The etiology of necrotizing enterocolitis (NEC) remains elusive despite known associations with several factors, including intestinal ischemia related to the effects of umbilical arterial catheterization on the mesenteric circulation. However, the role of the mesenteric venous circulation has yet to be studied as a potential cause of NEC. We examined the association between umbilical venous catheter (UVC) position and the development of NEC in premature infants.

DESIGN

A prospective cohort study was performed to examine the effect of UVC on portosystemic shunting via the ductus venosus (DV) and its potential role in NEC.

RESULTS

We recruited 132 premature infants, 62 of which had a birth weight ≤1,500 g. NEC was noted in 12 (19%) patients. All infants weighing ≤1,500 g underwent an attempt at UVC insertion. The UVC status was classified as appropriate (n = 39), unsuccessful (n = 9), or malpositioned (n = 14). Among the NEC patients, 7 (58%) had a UVC malposition and 3 (25%) had an unsuccessful attempt. These rates were significantly higher than in patients without NEC (14 and 12%, respectively). Multivariable logistic regression analysis confirmed birth weight (OR 2.2, 95% CI 1.2-4.7, p = 0.001) and UVC malpositioning (OR 6.9, 95% CI 1.6-35.4, p = 0.007) as independent risk factors associated with NEC.

CONCLUSIONS

Unrecognized withdrawal of a UVC into the portal vein or DV is associated with an increased incidence of NEC in infants weighing ≤1,500 g. The data support the need for additional studies to examine this effect. Confirmation of a causal relationship will raise the need to reassess UVC insertion criteria and strategies for more closely monitoring the catheter tip position.

Bevacizumab and interferon reduce venous recanalization following sclerotherapy

PURPOSE

The treatment of venous malformations is difficult because these lesions frequently recur after resection or sclerotherapy. The purpose of this study was to determine whether recanalization of sclerosed venous lumens could be prevented with systemic angiogenic inhibition using bevacizumab or peginterferon alfa-2a.

METHODS

To establish an animal model of recanalization of sclerosed facial veins, 18 rabbits had ethanol sclerotherapy of 1 facial vein followed by venography after 4weeks (n=6), 12weeks (n=6), and 24weeks (n=6). Subsequently, 21 different leporids underwent sclerotherapy of both facial veins (n=42 veins) and were treated pharmacologically in three ways: (1) control (n=14); bevacizumab (n=14); or peginterferon alfa-2a (n=14). Animals received 2 systemic drug doses 1month prior to and during the procedure. Vessel patency was determined 24weeks later using venography.

RESULTS

Venous recanalization occurred in 33.3% of sclerosed facial veins after 4weeks and 50.0% after 12 and 24weeks. For animals treated with systemic medication, recanalization occurred less frequently when bevacizumab (14.3%, n=2/14) (P=0.04) or peginterferon alfa-2a (7.7%, n=1/14) (P=0.01) was administered compared to controls (57.1%, n=8/14).

CONCLUSIONS

Systemic treatment with bevacizumab or peginterferon alfa-2a reduces venous recanalization following sclerotherapy in an animal model. Further studies are indicated to determine whether anti-angiogenic pharmacotherapy can prevent recurrence of venous malformations in humans after sclerotherapy.

Imaging features of kaposiform lymphangiomatosis

BACKGROUND

Kaposiform lymphangiomatosis is a rare, aggressive lymphatic disorder. The imaging and presenting features of kaposiform lymphangiomatosis can overlap with those of central conducting lymphatic anomaly and generalized lymphatic anomaly.

OBJECTIVE

To analyze the imaging findings of kaposiform lymphangiomatosis disorder and highlight features most suggestive of this diagnosis.

MATERIALS AND METHODS

We retrospectively identified and characterized 20 children and young adults with histopathological diagnosis of kaposiform lymphangiomatosis and radiologic imaging referred to the vascular anomalies center between 1995 and 2015.

RESULTS

The median age at onset was 6.5 years (range 3 months to 27 years). The most common presenting features were respiratory compromise (dyspnea, cough, chest pain; 55.5%), swelling/mass (25%), bleeding (15%) and fracture (5%). The thoracic cavity was involved in all patients; all patients had mediastinal involvement followed by lung parenchymal disease (90%) and pleural (85%) and pericardial (50%) effusions. The most common extra-thoracic sites of disease were the retroperitoneum (80%), bone (60%), abdominal viscera (55%) and muscles (45%). There was characteristic enhancing and infiltrative soft-tissue thickening in the mediastinum and retroperitoneum extending along the lymphatic distribution.

CONCLUSION

Kaposiform lymphangiomatosis has overlapping imaging features with central conducting lymphatic anomaly and generalized lymphatic anomaly. Presence of mediastinal or retroperitoneal enhancing and infiltrative soft-tissue disease along the lymphatic distribution, hemorrhagic effusions and moderate thrombocytopenia (50-100,000/μl) should favor diagnosis of kaposiform lymphangiomatosis.

Somatic Activating Mutations in GNAQ and GNA11 Are Associated with Congenital Hemangioma

Congenital hemangioma is a rare vascular tumor that forms in utero. Postnatally, the tumor either involutes quickly (i.e., rapidly involuting congenital hemangioma [RICH]) or partially regresses and stabilizes (i.e., non-involuting congenital hemangioma [NICH]). We hypothesized that congenital hemangiomas arise due to somatic mutation and performed massively parallel mRNA sequencing on affected tissue from eight participants. We identified mutually exclusive, mosaic missense mutations that alter glutamine at amino acid 209 (Glu209) in GNAQ or GNA11 in all tested samples, at variant allele frequencies (VAF) ranging from 3% to 33%. We verified the presence of the mutations in genomic DNA using a combination of molecular inversion probe sequencing (MIP-seq) and digital droplet PCR (ddPCR). The Glu209 GNAQ and GNA11 missense variants we identified are common in uveal melanoma and have been shown to constitutively activate MAPK and/or YAP signaling. When we screened additional archival formalin-fixed paraffin-embedded (FFPE) congenital cutaneous and hepatic hemangiomas, 4/8 had GNAQ or GNA11 Glu209 variants. The same GNAQ or GNA11 mutation is found in both NICH and RICH, so other factors must account for these tumors' different postnatal behaviors.

Impact of Screening for Hepatic Hemangiomas in Patients with Multiple Cutaneous Infantile Hemangiomas

OBJECTIVES

Hepatic hemangiomas are often found in association with multiple cutaneous infantile hemangiomas. Screening abdominal ultrasonography has been recommended for patients with five or more cutaneous lesions. We sought to determine whether hemangiomas found through screening had improved clinical outcomes.

METHODS

Patients entered into our hepatic hemangioma registry between 1995 and 2012 were reviewed.

RESULTS

Seventy-two patients with multiple cutaneous and hepatic hemangiomas were identified; 43 (60%) were detected through screening. The median age at diagnosis was 41 days for screened patients and 53 days for those not screened. Screening detected 40 (93%) multifocal and 3 (7%) diffuse hemangiomas, compared to 18 (62%) and 11 (38%), respectively, in the nonscreened group. Patients identified by screening had lower incidences of congestive heart failure and hypothyroidism and were less likely to receive treatment for their hemangiomas. The mortality rate in the children not screened was 28% (n = 8). None of the patients found by screening died (p < 0.001). Multivariate analysis of treated patients demonstrated that screening was a significant predictor of reduced mortality (p = 0.04).

CONCLUSION

Hepatic hemangiomas found through screening ultrasonography are less likely to develop serious clinical sequelae. Although the reasons for this may include detection of hemangiomas that are less likely to progress to symptomatic disease, it appears that it also allows for earlier intervention for more concerning (e.g. diffuse) subtypes. Screening may allow for closer surveillance and earlier treatment before life-threatening progression in a subset of infants with liver hemangiomas, preventing complications and reducing mortality.

Risk factors for mortality in patients with multifocal and diffuse hepatic hemangiomas

PURPOSE

Multifocal and diffuse hepatic hemangiomas are true infantile hemangiomas, which likely exist in a continuum. We reviewed our hepatic hemangioma registry to identify prognostic indicators for mortality.

METHODS

Registry records entered between 1995 and 2012 were reviewed. Clinical characteristics were evaluated for prognostic significance using the multivariable Cox proportional hazards model. Survival data were analyzed using the Kaplan-Meier product-limit method.

RESULTS

We identified 123 patients with multifocal (n=91) and diffuse (n=32) hepatic hemangiomas. Mortality was 16% (n=20); 40% (n=8) had multifocal and 60% (n=12) had diffuse lesions. A diagnosis of diffuse disease (hazard ratio: 9.9, 95% CI: 2.0-50.8, P=.002) and congestive heart failure (CHF) (hazard ratio: 3.9, 95% CI: 1.3-14.2, P=.031) were significant risk factors for mortality across the continuum; age at presentation, cardiomegaly, presence of shunts, and hypothyroidism were not statistically significant independent risk factors. Among patients with diffuse lesions, eight (67%) who died had abdominal compartment syndrome, which was also associated with mortality (P=.002).

CONCLUSIONS

Hepatic hemangioma patients with CHF or diffuse disease are at higher risk for mortality. Patients with multifocal lesions without CHF may go undetected until lesions become diffuse. Aggressive treatment of symptomatic patients and close follow-up of asymptomatic patients may improve mortality.

Lymphatic and other vascular malformative/overgrowth disorders are caused by somatic mutations in PIK3CA

OBJECTIVES

To test the hypothesis that somatic phosphatidylinositol-4,5-bisphospate 3-kinase, catalytic subunit alpha (PIK3CA) mutations would be found in patients with more common disorders including isolated lymphatic malformation (LM) and Klippel-Trenaunay syndrome (KTS).

STUDY DESIGN

We used next generation sequencing, droplet digital polymerase chain reaction, and single molecule molecular inversion probes to search for somatic PIK3CA mutations in affected tissue from patients seen at Boston Children's Hospital who had an isolated LM (n = 17), KTS (n = 21), fibro-adipose vascular anomaly (n = 8), or congenital lipomatous overgrowth with vascular, epidermal, and skeletal anomalies syndrome (n = 33), the disorder for which we first identified somatic PIK3CA mutations. We also screened 5 of the more common PIK3CA mutations in a second cohort of patients with LM (n = 31) from Seattle Children's Hospital.

RESULTS

Most individuals from Boston Children's Hospital who had isolated LM (16/17) or LM as part of a syndrome, such as KTS (19/21), fibro-adipose vascular anomaly (5/8), and congenital lipomatous overgrowth with vascular, epidermal, and skeletal anomalies syndrome (31/33) were somatic mosaic for PIK3CA mutations, with 5 specific PIK3CA mutations accounting for ∼ 80% of cases. Seventy-four percent of patients with LM from Seattle Children's Hospital also were somatic mosaic for 1 of 5 specific PIK3CA mutations. Many affected tissue specimens from both cohorts contained fewer than 10% mutant cells.

CONCLUSIONS

Somatic PIK3CA mutations are the most common cause of isolated LMs and disorders in which LM is a component feature. Five PIK3CA mutations account for most cases. The search for causal mutations requires sampling of affected tissues and techniques that are capable of detecting low-level somatic mosaicism because the abundance of mutant cells in a malformed tissue can be low.

Capillary-venous malformation in the upper limb

We present a group of patients with regional capillary malformations of the upper limbs and few additional findings other than prominent veins. We believe that this entity is the upper extremity equivalent of capillary-venous malformation of the lower limb and, likewise, belongs at the minor end of the spectrum of vascular disorders with overgrowth.

Diffuse capillary malformation in association with fetal pleural effusion: report of five patients

Capillary malformation (CM) can be a "red flag" for several syndromic vascular anomalies. We identified a subset of patients with diffuse CM and fetal pleural effusion and documented the type of CM, the etiology of the pleural effusion, the potential syndromic diagnosis, and outcome. Patients with a history of CM and fetal pleural effusion were identified by searching the database of patients evaluated at the Vascular Anomalies Center at Boston Children's Hospital. Standardized patient interviews and a retrospective review of records, photographs, and imaging studies were conducted. Five patients had diffuse CM and fetal pleural effusion. Two patients had macrocephaly-CM (M-CM), one had features of M-CM and CLOVES (congenital lipomatous overgrowth, vascular malformations, epidermal nevi, and spinal/skeletal anomalies and/or scoliosis), and one had diffuse CM with overgrowth. The pleural fluid was chylous in four patients. One patient had thoracic lymphatic malformation. Recurrent effusion occurred in one patient coincident with pneumonia at age 11 years. Four patients had a history of reactive airway disease and episodic pulmonary infections. The diagnosis of vascular anomaly-overgrowth syndromes, particularly M-CM, should be considered in neonates with fetal pleural effusion.

Male genital lymphedema: clinical features and management in 25 pediatric patients

PURPOSE

Genital lymphedema in the pediatric population is poorly understood. The purpose of this study was to determine the epidemiology, morbidity, and treatment outcomes for males with genital lymphedema.

MATERIALS AND METHODS

Male patients with genital lymphedema evaluated at our vascular anomalies center between 1995 and 2011 were reviewed. Etiology, age-of-onset, location, morbidity, and treatment were analyzed.

RESULTS

Of the 3889 patients with vascular anomalies, 25 (0.6%) had genital lymphedema: 92% (23/25) with primary and 24.0% (6/25) with familial/syndromic lymphedema. For primary disease, the mean age-of-onset was 4.5 ± 6.3 years with 60.9% (14/23) presenting in infancy, 13.0% (3/23) in childhood, and 26.1% (6/23) in adolescence. Combined penoscrotal lymphedema was identified in 72.0% (18/25) of patients; 19 children (76.0%) had concomitant lower extremity involvement. The most common complication was cellulitis (24.0%). Surgical contouring was performed in 44.0% (11/25) of patients. Patients with operative intervention and follow-up (n=6) had sustained improvement after a median of 4.2 years (range: 0.3-11.0).

CONCLUSIONS

Lymphedema of the male genitalia is typically idiopathic. Most patients develop swelling in infancy but can present in adolescence and occasionally childhood. The penis and scrotum are usually both involved and concurrent lower-extremity swelling is common. Surgical debulking can improve symptoms and appearance.

Overgrowth syndromes with complex vascular anomalies

Management of overgrowth syndromes with complex vascular anomalies is challenging. Careful analysis of the various clinical features by an interdisciplinary team of physicians experienced in this field is paramount to proper diagnostic and therapeutic approaches. In this article, we focus on the spectrum of the clinical presentation and the management strategies of the most common overgrowth syndromes with complex vascular anomalies.

ISSVA classification

Mulliken and Glowacki, in 1982 created a classification system of vascular anomalies which divided vascular anomalies into tumors and malformations which provided the framework for great advances in the management of these patients. This classification system was recently expanded at the 2014 ISSVA workshop in Melbourne. This revision again provides much greater detail including newly named anomalies and identified genes to account for recent advances in knowledge and clinical associations.

Hepatic vascular tumors

The most common hepatic vascular tumor in the pediatric population is the infantile hepatic hemangioma. Although these lesions have a spectrum of presentations, there are three main subtypes that have been described-focal, multifocal, and diffuse. An algorithm on the workup, treatment, and follow-up of these lesions can be based on this categorization. Recent shifts in the management of hemangiomas with beta-blockers (propranolol) have also influenced the treatment of hepatic hemangiomas. This article reviews the current understanding of hepatic hemangiomas and protocols in the management of these patients.

Management of visceral vascular anomalies

Vascular malformations affect the viscera less commonly than the head and neck, extremities, and extra-cavitary soft tissues. They present with a wide spectrum of symptoms and findings including pain, respiratory compromise, hemoptysis, chylothorax, ascites, gastrointestinal bleeding, and obstruction. Management options depend upon the subtype of malformation and anatomic extent and may include sclerotherapy, embolization, surgical extirpation, coloanal pull-through, and occasionally more innovative individualized surgical approaches.

Subfascial involvement in glomuvenous malformation

OBJECTIVE

Glomuvenous malformation (GVM) is an inherited autosomal dominant trait. The lesions, which appear as bluish nodules or plaque-like cutaneous elevations, are usually tender and more firm than sporadic venous malformations. Conventionally, the lesions are thought to be limited to the cutaneous and subcutaneous tissue planes. The objective was to characterize the depth of involvement of GVM lesions.

MATERIALS AND METHODS

Magnetic resonance imaging (MRI) findings in GVM were retrospectively evaluated by two radiologists. The signal characteristics, tissue distribution, pattern of contrast enhancement of the lesions in GVM were documented.

RESULTS

Thirty patients (19 female) aged 1-35 years (mean 18 years) were diagnosed with GVM based on clinical features (n = 20) and/or histopathological findings (n = 10). The lesions were present in the lower extremity (n = 15), upper extremity (n = 6), cervico-facial region (n = 6), pelvis (n = 2), and chest wall (n = 1). All patients had skin and subcutaneous lesions. Fifty percent of the patients (n = 15) demonstrated subfascial intramuscular (n = 15), intra-osseous (n = 1), and intra-articular involvement (n = 1).

CONCLUSION

Contrary to the conventional belief that GVMs are generally limited to the skin and subcutaneous tissue, deep subfascial extension of the lesions is common.

Safety and efficacy of bleomycin sclerotherapy for microcystic lymphatic malformation

PURPOSE

Sclerotherapy is the mainstay of treatment of macrocystic lymphatic malformation (LM), but the response using traditional sclerosants is much less beneficial in microcystic lesions. Intralesional bleomycin has been reported to be effective in microcystic LM; however, its use is limited by concerns about pulmonary fibrosis. The purpose of this study was to evaluate the safety and efficacy of bleomycin sclerotherapy in microcystic LM.

METHODS

The medical records and imaging studies of all patients with microcystic or combined LM who underwent percutaneous image-guided sclerotherapy using bleomycin were retrospectively reviewed. Only patients with pre- and postprocedure imaging were included. Thirty-one patients with a mean age of 13.4 years (range 3 months-31 years) were treated. Response was graded as complete (>90% size reduction), partial (25-90%), or minimal/no response (<25%). Pulmonary function tests (PFT) and chest X-rays were performed before the procedure. PFT were repeated at 6 months and 1 year postprocedure. Annual postprocedure chest X-rays were also performed.

RESULTS

The malformations were located in the head and neck (n = 27) and trunk (n = 4). The number of procedures ranged from 1 to 4 (mean 1.7). Up to 1 U/kg of bleomycin was injected per session, with a maximum of 15 U. The mean follow-up period was 3.2 years (range 1.5-5 years). There was complete response in 38% (n = 12), partial response in 58% (n = 18), and no response in 3% (n = 1). No complications were identified.

CONCLUSIONS

Preliminary indicate that sclerotherapy of microcystic LMs using bleomycin is effective and safe.

RASA1 functions in EPHB4 signaling pathway to suppress endothelial mTORC1 activity

Vascular malformations are linked to mutations in RAS p21 protein activator 1 (RASA1, also known as p120RasGAP); however, due to the global expression of this gene, it is unclear how these mutations specifically affect the vasculature. Here, we tested the hypothesis that RASA1 performs a critical effector function downstream of the endothelial receptor EPHB4. In zebrafish models, we found that either RASA1 or EPHB4 deficiency induced strikingly similar abnormalities in blood vessel formation and function. Expression of WT EPHB4 receptor or engineered receptors with altered RASA1 binding revealed that the ability of EPHB4 to recruit RASA1 is required to restore blood flow in EPHB4-deficient animals. Analysis of EPHB4-deficient zebrafish tissue lysates revealed that mTORC1 is robustly overactivated, and pharmacological inhibition of mTORC1 in these animals rescued both vessel structure and function. Furthermore, overexpression of mTORC1 in endothelial cells exacerbated vascular phenotypes in animals with reduced EPHB4 or RASA1, suggesting a functional EPHB4/RASA1/mTORC1 signaling axis in endothelial cells. Tissue samples from patients with arteriovenous malformations displayed strong endothelial phospho-S6 staining, indicating increased mTORC1 activity. These results indicate that deregulation of EPHB4/RASA1/mTORC1 signaling in endothelial cells promotes vascular malformation and suggest that mTORC1 inhibitors, many of which are approved for the treatment of certain cancers, should be further explored as a potential strategy to treat patients with vascular malformations.

Magnetic resonance lymphography of the thoracic duct after interstitial injection of gadofosveset trisodium: a pilot dosing study in a porcine model

BACKGROUND-RATIONALE: To investigate whether interstitial injection of gadofosveset trisodium (Ablavar®, Lantheus Medical, North Billerica, MA) would be suitable for thoracic duct (TD) imaging in a pig model.

METHODS AND RESULTS

Gadofosveset trisodium alone or premixed with 10% human serum albumin (HSA) was administered intradermally in the extremities of pigs at varying doses to visualize the TD by MRI. Two blinded readers evaluated MRIs for TD visibility. The inter-observer variability for all MR imaging sessions was assessed using the Spearman rank correlation test. MR lymphography using gadofosveset trisodium premixed with HSA yielded superior visualization of the TD compared to gadofosveset trisodium alone, with a high inter-observer agreement (correlation coefficient of 0.88 (p=0.00000115)).

CONCLUSIONS

We demonstrate that gadofosveset trisodium (premixed with 10%HSA) can be injected intradermally in order to perform MR lymphography of the thoracic duct. Since this agent is already FDA approved for MR imaging, the off-label use of it for imaging of the thoracic duct in humans is feasible, and the approach may prove to be beneficial for patients with TD abnormalities.