Steven J. Fishman

Somatic mosaic activating mutations in PIK3CA cause CLOVES syndrome.

Congenital lipomatous overgrowth with vascular, epidermal, and skeletal anomalies (CLOVES) is a sporadically occurring, nonhereditary disorder characterized by asymmetric somatic hypertrophy and anomalies in multiple organs. We hypothesized that CLOVES syndrome would be caused by a somatic mutation arising during early embryonic development. Therefore, we employed massively parallel sequencing to search for somatic mosaic mutations in fresh, frozen, or fixed archival tissue from six affected individuals. We identified mutations in PIK3CA in all six individuals, and mutant allele frequencies ranged from 3% to 30% in affected tissue from multiple embryonic lineages. Interestingly, these same mutations have been identified in cancer cells, in which they increase phosphoinositide-3-kinase activity. We conclude that CLOVES is caused by postzygotic activating mutations in PIK3CA. The application of similar sequencing strategies will probably identify additional genetic causes for sporadically occurring, nonheritable malformations.

The spectrum of vascular anomalies in patients with PTEN mutations: implications for diagnosis and management

Background: Mutations in the PTEN gene cause two disorders that predispose to cancer, Bannayan–Riley–Ruvalcaba and Cowden syndromes. Some patients with a PTEN mutation have only macrocephaly and autism, but they may still be at risk for neoplasms. Vascular anomalies occur in patients with a PTEN mutation, but they have not been systematically studied or precisely defined. Method: We analysed the clinical and radiological features of the vascular anomalies in 26 patients with PTEN mutations who were either seen or had their medical records reviewed at Children’s Hospital Boston. Results: All 23 patients who had their head circumference measured were macrocephalic, and all 13 male patients who were fully examined had penile freckling. Vascular anomalies were found in 14/26 (54%) of patients: 8/14 (57%) had multiple lesions and 11/13 (85%) who had cross-sectional imaging had intramuscular vascular lesions. Radiographic studies showed that 12/14 (86%) were fast-flow vascular anomalies, and angiography typically showed focal segmental dilatation of draining veins. Excessive ectopic fat in the vascular anomalies was present in 11/12 (92%) of patients on CT or MRI. Intracranial developmental venous anomalies (DVAs) were found in 8/9 (89%) of patients who had brain MRI with contrast. Conclusions: Vascular anomalies in patients with a PTEN mutation are typically multifocal intramuscular combinations of fast-flow channels and ectopic fat. Cerebral DVAs are very common. PTEN mutational analysis should be considered for all macrocephalic patients with fast-flow vascular anomalies or multiple intracranial DVAs.

A clinical decision rule to identify children at low risk for appendicitis

Objective. Computed tomography (CT) has gained widespread acceptance in the evaluation of children with suspected appendicitis. Concern has been raised regarding the long-term effects of ionizing radiation. Other means of diagnosing appendicitis, such as clinical scores, are lacking in children. We sought to develop a clinical decision rule to predict which children with acute abdominal pain do not have appendicitis. Methods. Prospective cohort study was conducted of children and adolescents who aged 3 to 18 years, had signs and symptoms suspicious for appendicitis, and presented to the emergency department between April 2003 and July 2004. Standardized data-collection forms were completed on eligible patients. Two low-risk clinical decision rules were created and validated using logistic regression and recursive partitioning. The sensitivity, negative predictive value (NPV), and negative likelihood ratio of each clinical rule were compared. Results. A total of 601 patients were enrolled. Using logistic regression, we created a 6-part score that consisted of nausea (2 points), history of focal right lower quadrant pain (2 points), migration of pain (1 point), difficulty walking (1 point), rebound tenderness/pain with percussion (2 points), and absolute neutrophil count of >6.75 × 103/μL (6 points). A score ≤5 had a sensitivity of 96.3% (95% confidence interval [CI]: 87.5–99.0), NPV of 95.6% (95% CI: 90.8–99.0), and negative likelihood ratio of .102 (95% CI: 0.026–0.405) in the validation set. Using recursive partitioning, a second low-risk decision rule was developed consisting of absolute neutrophil count of <6.75 × 103/μL, absence of nausea, and absence of maximal tenderness in the right lower quadrant. This rule had a sensitivity of 98.1% (95% CI: 90.1–99.9), NPV of 97.5% (95% CI: 86.8–99.9), and negative likelihood ratio of 0.058 (95% CI: 0.008–0.411) in the validation set. Theoretical application of the low-risk rules would have resulted in a 20% reduction in CT. Conclusions. Our low-risk decision rules can predict accurately which children are at low risk for appendicitis and could be treated safely with careful observation rather than CT examination.

Kaposiform hemangioendothelioma: atypical features and risks of Kasabach-Merritt phenomenon in 107 referrals

OBJECTIVE To examine the presentation characteristics of patients with Kaposiform hemangioendothelioma (KHE) to describe the spectrum of disease and risk factors for Kasabach-Merritt phenomenon (KMP). STUDY DESIGN A retrospective review of 163 patients referred to the Vascular Anomalies Center at Childrens Hospital Boston for KHE between 1991 and 2009 identified 107 patients with sufficient data for inclusion. RESULTS The prevalence of KHE in Massachusetts is ∼0.91 case per 100000 children. KHE manifested in infancy in 93% of cases, with 60% as neonates. Common presenting features included enlarging cutaneous lesion (75%), thrombocytopenia (56%), and musculoskeletal pain or decreased function (23%). Cutaneous KHE favored the extremities, especially overlying joints. In our cohort, 71% developed KMP (11% after initial presentation), and 11% of patients lacked cutaneous findings. Retroperitoneal and intrathoracic lesions, though less common, were complicated by KMP in 85% and 100% of cases, respectively. Compared with superficial lesions, KHE infiltrating into muscle or deeper was 6.3-fold more likely to manifest KMP and 18-fold higher if retroperitoneal or intrathoracic. KHE limited to bone or presenting after infancy did not manifest KMP. CONCLUSION An enlarging cutaneous lesion is the most common presenting feature of KHE in infancy. Older patients with KHE or those lacking cutaneous manifestations present with musculoskeletal complaints or atypical symptoms. The risk of KMP increases dramatically when tumor infiltrates muscle or when KHE arises in the retroperitoneum or mediastinum.

Blue Rubber Bleb Nevus Syndrome: Surgical Eradication of Gastrointestinal Bleeding

Objective:We report the largest clinical experience to date of surgically treated patients with blue rubber bleb nevus syndrome (BRBNS). Summary Background Data:BRBNS is a rare congenital disorder presenting with multifocal venous malformations of the skin, soft tissues, and gastrointestinal (GI) tract. Patients with BRBNS develop anemia from chronic GI bleeding, and require lifelong treatment with iron and blood transfusions. An aggressive surgical approach to treat the GI venous malformations of BRBNS has been considered unlikely to be successful because of the large number of lesions, their position throughout the GI tract, and the likelihood of recurrence. Based on our belief that eradicated lesions would not recur, we undertook the removal of all GI tract lesions in an effort to eliminate bleeding. Methods:Ten patients with BRBNS were treated from 1993 to 2002. Lesions were identified using complete GI endoscopy. The multiple venous malformations were removed by a combination of wedge resection, polypectomy, suture-ligation, segmental bowel resection, and band ligation. Results:Patient ages ranged from 2 to 36 years, and patients received an average of 53 prior blood transfusions. A mean of 137 focal GI venous malformations per patient were resected at operation (range 4–557), with a mean operative duration of 14 hours (range 7–23 hours). Only 1 patient who had a less extensive procedure developed recurrent GI bleeding. The mean follow-up period was 5.0 years (range 2.9–10.3 years). Conclusions:We believe that an aggressive excisional approach is indicated for the venous anomalies that cause GI bleeding in BRBNS.

Abdominal wall defects.

Survival for newborns with congenital abdominal wall defects (primarily omphalocele and gastroschisis) has improved, but controversy remains regarding etiology, anatomy and embryology, the role of prenatal diagnosis and mode of delivery, and initial management. A number of recent studies have added to our knowledge and understanding of several of these topics, while several others have raised questions regarding traditional initial management of these infants. Continued improvement in the survival of these infants can be anticipated with further understanding of the in utero and antepartum diagnosis and management of infants with these common congenital abnormalities.

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 Childrens 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 Childrens Hospital. RESULTS Most individuals from Boston Childrens 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 Childrens 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.

Videofetoscopically assisted fetal tissue engineering: Bladder augmentation

BACKGROUND/PURPOSE Treatment of several congenital anomalies is frequently hindered by lack of enough tissue for surgical reconstruction in the neonatal period. Minimally invasive harvest of fetal tissue, which is then processed through tissue engineering techniques in vitro while pregnancy is allowed to continue so that at delivery a newborn with a prenatally diagnosed congenital anomaly can benefit from having autologous, expanded tissue promptly available for surgical reconstruction at birth. This concept was applied to a bladder defect. METHODS Bladder exstrophy was surgically created in ten 90- to 95-day gestation fetal lambs, which were divided in two groups. In group I, a small fetal bladder specimen was harvested through a minimally invasive technique (videofetoscopy). Urothelial and smooth muscle cells were then separately cultivated and expanded in vitro for 55 to 60 days, resulting in a total of approximately 200 million cells. Seven to 10 days before delivery, the cells were seeded in two layers in a 16- to 20-cm2, 3-mm thick biodegradable polyglycolic acid polymer matrix. One to 4 days after delivery, autologous engineered tissue was used for surgical augmentation of the exstrophic bladder. In group II, no harvest was performed, and the bladder exstrophy was primarily closed after delivery. In both groups, a catheter was left inside the bladder for 3 weeks, at which time a cystogram was performed and the catheter then removed. In all animals, at 60 days, another cystogram was performed and urodynamic studies of the bladder were performed. The bladder was then removed for histological analysis. RESULTS Fetal survival rate was 100%. One newborn died immediately after the implantation of the engineered bladder from an anesthetic accident. The other nine (four in group I and five in group II) survived. One of the animals from group I lost its bladder catheter prematurely and had a urinary leak detected only at the time of death. There were no other complications. The engineered bladders were more compliant (P < .05) and had greater capacity pressures greater than 20 mm Hg (P < .05) than those closed primarily. Histological analysis of the engineered tissue showed a multilayered urothelial lining on the luminal side and overlying layers of smooth muscle cells surrounded by connective tissue. CONCLUSIONS Videofetoscopically assisted fetal bladder engineering may be a viable alternative for prompt bladder reconstruction at birth. The architecture of autologous engineered fetal bladder tissue resembles that of native bladder. This concept may prove useful for the treatment of certain human neonatal conditions such as bladder and cloacal exstrophies.

Lung abscess versus necrotizing pneumonia: implications for interventional therapy

Objective. To assess and contrast the role of interventional therapy for two types of cavitating pneumonias: lung abscess and necrotizing pneumonia. Materials and methods. We retrospectively reviewed the imaging, interventional therapy, and outcome of 14 children seen between February 1987 and January 1996 with lung abscess and 9 with necrotizing pneumonia. All children were treated with antibiotics prior to intervention. Pulmonary parenchymal fluid was percutaneously aspirated from ten lung abscesses and three necrotizing pneumonias. Percutaneous catheters drained five lung abscesses. Pleural drainage was performed for three lung abscesses and eight necrotizing pneumonias. Results. All 14 children with lung abscesses had positive Gram stains of the pulmonary fluid; 13 cultures were positive. All 14 defervesced within 48 h of intervention. None developed a bronchopleural fistula. All nine necrotizing pneumonias were presumed to be sequelae of prior pneumonia. Streptococcus pneumoniae was the only organism as documented by pleural fluid latex fixation in three patients, gram stain in two, and culture in only one. Seven of these children developed pneumatoceles, five developed bronchopleural fistulae, and three required long-term chest tubes for persistent pneumothoraces. Conclusion. Aggressive interventional therapy can be diagnostic and therapeutic in the infected lung abscess. Interventional therapy can be harmful in postinfectious necrotizing pneumonia.

Extracranial Arteriovenous Malformations: Natural Progression and Recurrence after Treatment

BACKGROUND Arteriovenous malformation is a dynamic vascular anomaly; it expands with age and after treatment. This study analyzed the pattern of arteriovenous malformation progression and frequency of recurrence after therapy. METHODS Patients with cutaneous and soft-tissue arteriovenous malformation were reviewed. Progression was defined as advancement to a higher Schobinger stage (I through IV) before treatment. Recurrence was defined as expansion following embolization or resection. The effect of sex, location, size, adolescence, pregnancy, and stage on progression or recurrence was analyzed. RESULTS The study included 272 patients. Children with stage I arteriovenous malformation had a 43.8 percent risk of progression before adolescence and an 82.6 percent risk before adulthood; the remaining children had progression in adulthood. Progression was more common during adolescence (56.0 percent; 95 percent confidence interval, 46.5 to 65.2) compared with childhood (38.8 percent; 95 percent confidence interval, 32.4 to 45.4) (p = 0.002). The average age at progression was 12.7 +/- 11.1 years. Diffuse arteriovenous malformations were more likely to progress compared with localized lesions (p < 0.001). Sex (p = 0.46), location (p = 0.36), and pregnancy (p = 0.20) did not influence expansion. Resection (with or without embolization) had a lower recurrence rate (81 percent) and longer time to recurrence (42.7 percent >1 year), compared with embolization alone (98 percent and 14.4 percent >1 year, respectively) (p < 0.001). Recurrence was less likely when lower staged lesions were treated (p < 0.001) and did not correlate with sex (p = 0.10), location (p = 0.60), size (p = 0.07), or age (p = 0.21). CONCLUSIONS Arteriovenous malformation is likely to progress before adulthood, particularly during adolescence, and usually reexpands following treatment. Resection (with or without embolization) for lower staged or localized arteriovenous malformation offers the best chance for long-term control.