Clinical differentiation between Proteus syndrome and hemihyperplasia: description of a distinct form of hemihyperplasia

Genotypes and phenotypes heterogeneity in PIK3CA-related overgrowth spectrum and overlapping conditions: 150 novel patients and systematic review of 1007 patients with PIK3CA pathogenetic variants

BACKGROUND

Postzygotic activating PIK3CA variants cause several phenotypes within the PIK3CA-related overgrowth spectrum (PROS). Variant strength, mosaicism level, specific tissue involvement and overlapping disorders are responsible for disease heterogeneity. We explored these factors in 150 novel patients and in an expanded cohort of 1007 PIK3CA-mutated patients, analysing our new data with previous literature to give a comprehensive picture.

METHODS

We performed ultradeep targeted next-generation sequencing (NGS) on DNA from skin biopsy, buccal swab or blood using a panel including phosphatidylinositol 3-kinase/AKT/mammalian target of rapamycin pathway genes and GNAQ, GNA11, RASA1 and TEK. Additionally, 914 patients previously reported were systematically reviewed.

RESULTS

93 of our 150 patients had PIK3CA pathogenetic variants. The merged PROS cohort showed that PIK3CA variants span thorough all gene domains, some were exclusively associated with specific PROS phenotypes: weakly activating variants were associated with central nervous system (CNS) involvement, and strongly activating variants with extra-CNS phenotypes. Among the 57 with a wild-type PIK3CA allele, 11 patients with overgrowth and vascular malformations overlapping PROS had variants in GNAQ, GNA11, RASA1 or TEK.

CONCLUSION

We confirm that (1) molecular diagnostic yield increases when multiple tissues are tested and by enriching NGS panels with genes of overlapping 'vascular' phenotypes; (2) strongly activating PIK3CA variants are found in affected tissue, rarely in blood: conversely, weakly activating mutations more common in blood; (3) weakly activating variants correlate with CNS involvement, strong variants are more common in cases without; (4) patients with vascular malformations overlapping those of PROS can harbour variants in genes other than PIK3CA.

Postmortem Diagnosis of the Proteus Syndrome by Next Generation Sequencing of Affected Brain Tissue

We report a case of a somatic overgrowth syndrome diagnosed at forensic autopsy with the aid of next generation sequencing as Proteus syndrome. Somatic overgrowth syndromes result from spontaneous somatic mutations that arise early in development and display a mosaic pattern of expression in patient tissues. Due to the temporal and anatomic heterogeneity of these syndromes, phenotypes vary widely, resulting in clinical overlap. Furthermore, the variable ratio of mutated to nonmutated cells in patient tissue can result in low-level mutations that could be missed using Sanger sequencing. Due to these factors, recent literature points to next generation sequencing (NGS) as an adjunct to diagnosis of these rare entities. A male in his fourth decade of life presented to our forensic autopsy service with physical features suggestive of a somatic overgrowth syndrome. Due to the paucity of clinical information accompanying the individual, a definitive diagnosis based on physical characteristics, alone, was not possible. Next generation sequencing of affected formalin-fixed and paraffin-embedded brain tissue confirmed the presence of the variant in AKT1 (c.49G>A, p.Glu17Lys, in 14.13% of reads) found in Proteus syndrome. To our knowledge, this is the first report of the mosaic variant of AKT1 detected in brain tissue and the first reported case of a postmortem diagnosis of Proteus syndrome with the aid of NGS. We conclude that NGS can be used as an adjunctive method to support a specific diagnosis among the somatic overgrowth syndromes postmortem in the absence of sufficient clinical history.

Clinical and molecular data in cases of prenatal localized overgrowth disorder: major implication of genetic variants in PI3K-AKT-mTOR signaling pathway

OBJECTIVES

To describe clinical and molecular findings in a French multicenter cohort of fetuses with prenatal diagnosis of congenital abnormality and suspicion of a localized overgrowth disorder (LOD) suggestive of genetic variants in the PI3K-AKT-mTOR signaling pathway.

METHODS

We analyzed retrospectively data obtained between 1 January 2013 and 1 May 2020 from fetuses with brain and/or limb overgrowth referred for molecular diagnosis of PI3K-AKT-mTOR pathway genes by next-generation sequencing (NGS) using pathological tissue obtained by fetal autopsy. We also assessed the diagnostic yield of amniotic fluid.

RESULTS

During the study period, 21 subjects with LOD suspected of being secondary to a genetic variant of the PI3K-AKT-mTOR pathway were referred for analysis. Of these, 17 fetuses had brain overgrowth, including six with isolated megalencephaly (MEG) and 11 with hemimegalencephaly (HMEG). Of the six with MEG, germline variants were identified in four cases, in either PIK3R2, AKT3 or MTOR, and a postzygotic PIK3R2 variant was found in the other two cases. Of the 11 with HMEG, a postzygotic PIK3CA variant was found in three fetuses with extracerebral features of PIK3CA-related overgrowth spectrum, and in seven fetuses with isolated HMEG. No pathogenic variant was identified in the 11^th case with HMEG. Four fetuses with limb overgrowth also had one or more lymphatic malformations (LM) and harbored a postzygotic PIK3CA variant. NGS on cultured amniocytes performed in 10 cases, of which nine had been found positive on analysis of pathological fetal tissue, showed variants in four, in either PIK3CA, PIK3R2 or AKT3.

CONCLUSIONS

Isolated MEG or HMEG may lead to identification of genetic variants in the PI3K-AKT-mTOR signaling pathway. Cases of limb overgrowth and LM or isolated HMEG are likely associated with PIK3CA variants. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Phenotypic and molecular characterization of five patients with PIK3CA-related overgrowth spectrum (PROS)

Somatic and germline PI3K-AKT-mTOR pathway pathogenic variants are involved in several segmental overgrowth phenotypes such as the PIK3CA-related overgrowth spectrum (PROS), Proteus syndrome, and PTEN hamartoma tumor syndrome. In this study, we describe five patients with PROS. We identified by high-throughput sequencing four different somatic PIK3CA pathogenic variants in five individuals. The Glu726Lys variant, which was previously reported in megalencephaly-capillary malformation-polymicrogyria (MCAP) syndrome, was identified in two patients with unclassified PROS. The Cys420Arg substitution, which was previously reported in CLOVES, was found in a patient with fibroadipose hyperplasia. Additionally, relatively rare pathogenic variants, His1047Tyr and Tyr1021Cys, were detected in two patients with MCAP. Therefore, we suggest performing deep sequencing of PIK3CA in all patients with suspected PROS, instead of targeted polymerase chain reaction for hotspot pathogenic variants.

Phenotype and Surgical Treatment in a Case of Proteus Syndrome With Craniofacial and Oral Findings

BACKGROUND/AIM

Proteus syndrome is a sporadic disease that is particularly noticeable due to the disproportional growth of body segments. The disease is a genetic mosaic. The mutations can arise from any of the germ layers, an explanation of the very variable phenotype. The aim of this report is to communicate the diagnosis and management of an unusual case of Proteus Syndrome with special attention to oral and craniofacial findings.

CASE REPORT

A 15-year-old patient was referred for surgical treatment of pronounced skull malformations and correction of oral mucosal hyperplasia. Treatment caused significant improvement in facial appearance and oral soft tissue conditions.

CONCLUSION

Surgical measures adapted to the local findings and symptoms can often relieve severe disfigurement of the patient.

PIK3CA vascular overgrowth syndromes: an update

PURPOSE OF REVIEW

Over the past decade many previously poorly understood vascular malformation disorders have been linked to somatic activating mutations in PIK3CA, which regulates cell survival and growth via activation of the mTOR1-AKT pathway. The goal of this article is to describe and provide an update on the clinical features, complications, and management strategies for the PIK3CA-related overgrowth spectrum (PROS).

RECENT FINDINGS

PROS encompasses a heterogenous group of disorders with complications related to the tissues harboring the mutation. Vascular malformation syndromes, such as Klippel-Trenaunay syndrome and Congenital Lipomatous Overgrowth Vascular malformations Epidermal nevi and Skeletal abnormalities, have an increased risk of thromboembolic complications, which is accentuated postprocedurally. Asymmetric overgrowth, particularly of limbs, results in a high rate of orthopedic complications. Hypoglycemia screening in the neonatal period and ongoing monitoring for growth failure is recommended in megalencephaly capillary malformation due to its association with multiple endocrinopathies. Recently, sirolimus, an mTOR1 inhibitor, has shown promise in vascular anomalies and now PROS. PIK3CA direct inhibitor, Alpelisib (BYL719), was recently trialed with significant clinical benefit.

SUMMARY

As the pathogenesis of these conditions is better elucidated and targeted treatments are developed, recognizing the clinical features, comorbidities, and evolving therapeutic landscape across the PROS spectrum becomes more crucial for optimization of care.

A dyadic genotype-phenotype approach to diagnostic criteria for Proteus syndrome

Phenotype-based diagnostic criteria were developed for Proteus syndrome in 1999 and updated in 2006. Subsequently, the causative mosaic gene alteration was discovered, the c.49G>A p.E17K variant in AKT1. As well, a number of overlapping overgrowth disorders attributable to mosaic PIK3CA variants have now been characterized, leading to the designation of PIK3CA-related overgrowth spectrum (PROS). Finally, ongoing work to better characterize Proteus syndrome has led to identification of additional features of that disorder that could be useful in diagnostic criteria. We have taken the opportunity of these discoveries to re-evaluate the Proteus syndrome diagnostic criteria. Here we propose a new set of diagnostic criteria that establishes a weighted, point-based system for the phenotypic attributes and then integrates that with the potential molecular test results to result in one of two designations: AKT1-related Proteus syndrome or AKT1-related overgrowth spectrum. A patient whose only manifestation is an AKT1 c.49G>A-positive tumor would receive neither of these designations. Here we review the rational basis of diagnostic criteria and argue that a unitary diagnostic entity is a distinct gene-phenotype dyad and that this should be the model for all mendelian disorders. The gene-alone or phenotype-alone approach is inadequate to rigorously delineate a unitary diagnostic entity.

Characterization of the hepatosplenic and portal venous findings in patients with Proteus syndrome

Proteus syndrome (PS) is a rare disorder caused by a mosaic AKT1 variant that comprises patchy overgrowth of tissues derived from all three germinal layers affecting multiple viscera. We sought to delineate the extent of hepatoportal manifestations in patients with PS. We identified patients with PS who had abdominal imaging from 1989 to 2015 in a natural history study. Imaging was characterized for evidence of focal findings in the liver, spleen, and portal vasculature and for organomegaly. Relevant clinical and laboratory data were compared among those with or without organomegaly. Abdominal imaging was available on 38 patients including 20 who had serial studies. Nine patients had focal hepatic lesions including vascular malformations (VMs). Focal splenic abnormalities were noted in seven patients. Patients without cutaneous VMs did not have visceral VMs. Nine patients had splenomegaly, 12 had portal vein dilation, and 4 had hepatomegaly. There was a weak correlation of portal vein dilation to spleen height ratio (r² = 0.18, p < .05). On laboratory evaluation, hepatic function was normal but there was thrombocytopenia in those with splenomegaly; platelet counts were 179 ± 87K/μL compared to those with normal spleen size at 253 ± 57K/μL (p < .05). Overall, focal hepatosplenic abnormalities occurred in 11 of 38 (29%) patients with PS. Splenomegaly and portal venous dilation were both found in 8 of 38 (21%) patients; however, other than relative thrombocytopenia, there was no evidence of portal hypertension. Although the AKT1-E17K somatic variant is a suspected oncogene, there were no malignant lesions identified in this study.

The effect of rapamycin, NVP-BEZ235, aspirin, and metformin on PI3K/AKT/mTOR signaling pathway of PIK3CA-related overgrowth spectrum (PROS)

The phosphatidylinositol 3-kinase (PI3K)/AKT/mTOR signaling pathway is critical for cellular growth and metabolism. Recently, mosaic or segmental overgrowth, a clinical condition caused by heterozygous somatic activating mutations in PIK3CA, was established as PIK3CA-related overgrowth spectrum (PROS). In this study, we report a Japanese female diagnosed with PROS, who presented with hyperplasia of the lower extremities, macrodactyly, multiple lipomatosis, and sparse hair. Sequencing and mutant allele frequency analysis of PIK3CA from affected tissues revealed that the patient had a heterozygous mosaic mutation (c.3140A>G [p.H1047R]) in PIK3CA and that there were higher mutant allele frequencies from samples with a larger amount of subcutaneous adipose tissue. We established two fibroblast cell lines from the patient, harboring high and low frequencies of the mosaic mutation, in which AKT and S6 showed higher level of phosphorylation compared with three control fibroblasts, indicating that PI3K/AKT/mTOR signaling is activated. We assessed the therapeutic effects of four compounds (rapamycin, NVP-BEZ235, aspirin, and metformin) on PI3K/AKT/mTOR signaling pathway and cell growth. All four compounds suppressed S6 phosphorylation and inhibited cell growth of the patient-derived fibroblast cell lines. However, only metformin mildly inhibited the growth of the control fibroblast cell lines. Since PROS is a congenital disorder, drugs for therapy should take into consideration the natural growth of children. Thus, metformin is a candidate drug for treating PROS in growing children.

PI3K Signaling in Tissue Hyper-Proliferation: From Overgrowth Syndromes to Kidney Cysts

The members of the PhosphoInositide-3 Kinase (PI3K) protein family are well-known regulators of proliferative signals. By the generation of lipid second messengers, they mediate the activation of AKT/PKB (AKT) and mammalian Target Of Rapamycin (mTOR) pathways. Although mutations in the PI3K/AKT/mTOR pathway are highly characterized in cancer, recent evidence indicates that alterations in the proliferative signals are major drivers of other diseases such as overgrowth disorders and polycystic kidney disease. In this review, we briefly summarize the role of the PI3K/AKT/mTOR pathway in cell proliferation by comparing the effect of alterations in PI3K enzymes in different tissues. In particular, we discuss the most recent findings on how the same pathway may lead to different biological effects, due to the convergence and cooperation of different signaling cascades.

Molecular and Functional Characterization of Three Different Postzygotic Mutations in PIK3CA-Related Overgrowth Spectrum (PROS) Patients: Effects on PI3K/AKT/mTOR Signaling and Sensitivity to PIK3 Inhibitors

Background

PIK3CA-related overgrowth spectrum (PROS) include a group of disorders that affect only the terminal portion of a limb, such as type I macrodactyly, and conditions like fibroadipose overgrowth (FAO), megalencephaly-capillary malformation (MCAP) syndrome, congenital lipomatous asymmetric overgrowth of the trunk, lymphatic, capillary, venous, and combined-type vascular malformations, epidermal nevi, skeletal and spinal anomalies (CLOVES) syndrome and Hemihyperplasia Multiple Lipomatosis (HHML). Heterozygous postzygotic PIK3CA mutations are frequently identified in these syndromes, while timing and tissue specificity of the mutational event are likely responsible for the extreme phenotypic variability observed.

Methods

We carried out a combination of Sanger sequencing and targeted deep sequencing of genes involved in the PI3K/AKT/mTOR pathway in three patients (1 MCAP and 2 FAO) to identify causative mutations, and performed immunoblot analyses to assay the phosphorylation status of AKT and P70S6K in affected dermal fibroblasts. In addition, we evaluated their ability to grow in the absence of serum and their response to the PI3K inhibitors wortmannin and LY294002 in vitro.

Results and Conclusion

Our data indicate that patients’ cells showed constitutive activation of the PI3K/Akt pathway. Of note, PI3K pharmacological blockade resulted in a significant reduction of the proliferation rate in culture, suggesting that inhibition of PI3K might prove beneficial in future therapies for PROS patients.

PIK3CA-related overgrowth spectrum (PROS): diagnostic and testing eligibility criteria, differential diagnosis, and evaluation

Somatic activating mutations in the phosphatidylinositol-3-kinase/AKT/mTOR pathway underlie heterogeneous segmental overgrowth phenotypes. Because of the extreme differences among patients, we sought to characterize the phenotypic spectrum associated with different genotypes and mutation burdens, including a better understanding of associated complications and natural history. Historically, the clinical diagnoses in patients with PIK3CA activating mutations have included Fibroadipose hyperplasia or Overgrowth (FAO), Hemihyperplasia Multiple Lipomatosis (HHML), Congenital Lipomatous Overgrowth, Vascular Malformations, Epidermal Nevi, Scoliosis/Skeletal and Spinal (CLOVES) syndrome, macrodactyly, Fibroadipose Infiltrating Lipomatosis, and the related megalencephaly syndromes, Megalencephaly-Capillary Malformation (MCAP or M-CM) and Dysplastic Megalencephaly (DMEG). A workshop was convened at the National Institutes of Health (NIH) to discuss and develop a consensus document regarding diagnosis and treatment of patients with PIK3CA-associated somatic overgrowth disorders. Participants in the workshop included a group of researchers from several institutions who have been studying these disorders and have published their findings, as well as representatives from patient-advocacy and support groups. The umbrella term of "PIK3CA-Related Overgrowth Spectrum (PROS)" was agreed upon to encompass both the known and emerging clinical entities associated with somatic PIK3CA mutations including, macrodactyly, FAO, HHML, CLOVES, and related megalencephaly conditions. Key clinical diagnostic features and criteria for testing were proposed, and testing approaches summarized. Preliminary recommendations for a uniform approach to assessment of overgrowth and molecular diagnostic testing were determined. Future areas to address include the surgical management of overgrowth tissue and vascular anomalies, the optimal approach to thrombosis risk, and the testing of potential pharmacologic therapies.

Myocardial fat overgrowth in Proteus syndrome

Proteus syndrome (PS) is a rare, mosaic disorder with asymmetric and distorting overgrowth of the skeletal system, skin, and adipose tissues. Cardiac abnormalities are rare in this syndrome and only two prior cases have been reported. Many patients with PS followed at our institution underwent transthoracic echocardiograms for preoperative evaluation or as work-up for associated pulmonary disease. Some were noted to have prominent, focal echodense areas in the myocardium. We further investigated cardiac findings in a cohort of children and adult patients with PS. Patients with abnormal echocardiograms were referred for cardiac magnetic resonance imaging, Holter monitoring, and exercise treadmill testing. Twenty children and adults with PS, age 24 months to 50 years old, underwent transthoracic echocardiograms. Seven patients (35%) had focal bright echodense areas within the myocardium suggesting fatty infiltration. The majority of patients had significant involvement of the interventricular septum. The cardiac characteristics of all patients with fatty infiltration on transthoracic echocardiograms were compared to Proteus patients without these findings. There were no significant differences in chamber sizes, mass, systolic or diastolic function. No increased risk of conduction defects or arrhythmias was found. This study shows that abnormal fat overgrowth is a common finding in the myocardium in patients with Proteus syndrome; however, it is not associated with functional derangements or arrhythmias. Further evaluation of a larger number of Proteus patients is needed in order to determine the frequency and prognosis of cardiac involvement. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Two cases of hemihyperplasia-multiple lipomatosis syndrome and review of asymmetric hemihyperplasia syndromes

Hemihyperplasia-multiple lipomatosis syndrome (HHML) is a condition characterized by asymmetric nonprogressive overgrowth, multiple lipomas, and superficial vascular malformations. We present two cases of HHML to enhance the diagnostic acumen of dermatologists and avoid potential misdiagnosis of this rare but probably underrecognized entity. We also provide a brief review of asymmetric overgrowth syndromes, which have overlapping yet distinct clinical manifestations.

Clinical delineation and natural history of the PIK3CA-related overgrowth spectrum

Somatic mutations in the phosphatidylinositol/AKT/mTOR pathway cause segmental overgrowth disorders. Diagnostic descriptors associated with PIK3CA mutations include fibroadipose overgrowth (FAO), Hemihyperplasia multiple Lipomatosis (HHML), Congenital Lipomatous Overgrowth, Vascular malformations, Epidermal nevi, Scoliosis/skeletal and spinal (CLOVES) syndrome, macrodactyly, and the megalencephaly syndrome, Megalencephaly-Capillary malformation (MCAP) syndrome. We set out to refine the understanding of the clinical spectrum and natural history of these phenotypes, and now describe 35 patients with segmental overgrowth and somatic PIK3CA mutations. The phenotypic data show that these previously described disease entities have considerable overlap, and represent a spectrum. While this spectrum overlaps with Proteus syndrome (sporadic, mosaic, and progressive) it can be distinguished by the absence of cerebriform connective tissue nevi and a distinct natural history. Vascular malformations were found in 15/35 (43%) and epidermal nevi in 4/35 (11%) patients, lower than in Proteus syndrome. Unlike Proteus syndrome, 31/35 (89%) patients with PIK3CA mutations had congenital overgrowth, and in 35/35 patients this was asymmetric and disproportionate. Overgrowth was mild with little postnatal progression in most, while in others it was severe and progressive requiring multiple surgeries. Novel findings include: adipose dysregulation present in all patients, unilateral overgrowth that is predominantly left-sided, overgrowth that affects the lower extremities more than the upper extremities and progresses in a distal to proximal pattern, and in the most severely affected patients is associated with marked paucity of adipose tissue in unaffected areas. While the current data are consistent with some genotype-phenotype correlation, this cannot yet be confirmed.

CLOVES syndrome

A cohort of patients with overgrowth syndromes has been identified with congenital lipomatous overgrowth, dysregulated fat deposits, and mixed vascular malformations. The acronym CLOVES was given on a heuristic basis to stand for congenital lipomatous overgrowth (CLO), vascular malformation (V), epidermal nevi (E), and scoliosis and spinal deformities (S). These patients have upper limb anomalies with variable phenotypes. Although hand anomalies alone cannot make the diagnosis, the foot, truncal, cutaneous and spinal anomalies are particularly diagnostic. CLOVES syndrome has emerged as a distinct clinical entity diagnosed by clinical and radiographic examinations. The overgrowth pattern is now easily distinguished from other overgrowth syndromes.

Proteus syndrome review: molecular, clinical, and pathologic features

Proteus syndrome is caused by an activating AKT1 mutation (c.49G>A, p.Glu17Lys). Many variable features are possible in this mosaic disorder, including: (i) disproportionate, asymmetric, and distorting overgrowth; (ii) bone abnormalities different from those observed in other disorders; (iii) a characteristic cerebriform connective tissue nevus made up of highly collagenized connective tissue; (iv) epidermal nevi in early life, consisting of acanthosis and hyperkeratosis; (v) vascular malformations of the capillary, venous, or lymphatic types; (vi) dysregulated adipose tissue including lipomas, lipohypoplasia, fatty overgrowth, and localized fat deposits; (vii) other unusual features, including bullous lung alterations; specific neoplasms; a facial phenotype associated with intellectual disability and/or seizures, and/or brain malformations; and (viii) deep vein thrombosis, resulting in premature death. Concluding remarks address diagnostic criteria, natural history, management, psychosocial issues, and differential diagnosis.

Commonest overgrowth syndromes

Overgrowth syndromes, although rare, are diagnosed more frequently lately. Major progress, such as the identification of genetic causes, has recently enhanced the delineation of the characteristic and noncharacteristic manifestations, phenotype-genotype correlations and knowledge of the underlying pathophysiologic mechanisms. This review provides a summary of the most important overgrowth syndromes aiming to familiarize the treating physician with the cardinal clinical features involved in these syndromes that encompass overgrowth, but also have a variety of other clinical manifestations (neurologic, musculoskeletal, skin, and accompanying tumors).

Assessment and management of the orthopedic and other complications of Proteus syndrome

PURPOSE

A multidisciplinary workshop was convened at the National Institutes of Health (NIH) to discuss the management of the orthopedic and other complications of Proteus syndrome (PS), a progressive, disproportionate overgrowth disorder. While PS poses many complex challenges, the focus of the workshop was the management of the asymmetric and disorganized skeletal overgrowth that characterizes this multisystem disorder.

METHODS

Workshop participants developed recommendations for clinical research and patient management and surveillance to maximize the benefits and reduce the risks of surgical and other interventions.

RESULTS

Recommendations for clinical care and management included assessments of skeletal overgrowth and its progression with modalities such as X-ray, magnetic resonance imaging (MRI), dual-energy X-ray absorptiometry, and computerized tomography (CT) imaging. The recommendations also cover the assessment of non-orthopedic complications of PS that significantly impact surgical risk, such as pulmonary embolism and lung bullae. Surgical considerations in PS include assessment of the contribution of contractures to deformities and prophylactic soft-tissue release, aggressive and early use of epiphysiodesis and epiphysiostasis, amputation, and spinal bracing.

CONCLUSION

Decisions on the timing of orthopedic procedures in children with PS are challenging because they entail balancing the risks of intervention in this high-risk and complex population against the increasing morbidity that patients experience with progressive bony overgrowth. If surgery is delayed too long, the condition may become inoperable. We hope that these recommendations will help clinicians gather appropriate data and assist their patients in making timely treatment decisions.

Epidermal nevi

Nevi or nests of cells may be made up of a variety of cell types. The cell types that live in the epidermis include epidermal cells or keratinocytes, sebaceous glands, hair follicles, apocrine and eccrine glands, and smooth muscle cells. This article discusses epidermal or keratinocyte nevi, nevus sebaceous, nevus comedonicus, smooth muscle hamartomas, and inflammatory linear verrucous epidermal nevi. Syndromes associated with epidermal nevi are also reviewed.

Progressive overgrowth of the cerebriform connective tissue nevus in patients with Proteus syndrome

BACKGROUND

Proteus syndrome is a rare overgrowth disorder that almost always affects the skin.

OBJECTIVE

Our purpose was to evaluate progression of skin lesions in patients with Proteus syndrome.

METHODS

Skin findings were documented in 36 patients with Proteus syndrome. Progression of skin lesions in 16 of these patients was assessed by comparing photographs obtained on repeated visits for an average total duration of 53 months.

RESULTS

The skin lesion most characteristic of Proteus syndrome, the cerebriform connective tissue nevus, showed progression in 13 children but not in 3 adults. The cerebriform connective tissue nevus progressed by expansion into previously uninvolved skin, increased thickness, and development of new lesions. Lipomas increased in size, number, or both in 8 of 10 children with lipomas. In contrast, epidermal nevi and vascular malformations generally did not spread or increase in number.

LIMITATIONS

Only 3 adults with Proteus syndrome were evaluated longitudinally.

CONCLUSION

The cerebriform connective tissue nevus in Proteus syndrome grows throughout childhood but tends to remain stable in adulthood.

Hemihyperplasia-multiple lipomatosis syndrome: an underdiagnosed entity in children with asymmetric overgrowth

Hemihyperplasia can be found as an isolated abnormality, or as a predominant associated feature of an asymmetric overgrowth syndrome. This report describes 2 patients with hemihyperplasia-multiple lipomatosis syndrome. The finding of hemihyperplasia prompts careful examination for associated lipomatous lesions. Close follow-up is required because progressive growth of lipomatous lesions can be encountered as well as recurrence after excision.

Characterization of a distinct syndrome that associates complex truncal overgrowth, vascular, and acral anomalies: a descriptive study of 18 cases of CLOVES syndrome

Overgrowth syndromes with complex vascular anomalies pose a challenge for diagnosis and management. The purpose of this descriptive study is to present a cohort of patients with congenital lipomatous overgrowth, vascular malformations, and epidermal nevi syndrome, a distinct clinical phenotype characterized by a complex truncal-lipomatous mass, vascular, acral, and other anomalies. This cohort was ascertained following review of patient data entered into the Vascular Anomalies Center database of the Children's Hospital, Boston over a period of 7 years. Clinical data, imaging findings, and the photographic archive were reviewed. The search identified 18 unrelated patients with a distinct phenotype. Variable portions of the truncal masses observed in these patients were composed of a lymphatic malformation. Capillary malformations and high-flow lesions were commonly encountered. The lipomatous mass infiltrated the adjacent anatomic spaces and was associated with capillary, lymphatic, venous, and arteriovenous vascular malformations. Paraspinal-intraspinal extension was associated with morbid sequelae. Acral deformities included large, wide feet and hands, macrodactyly, and a wide sandal gap. Scoliosis and other musculoskeletal, neurologic, renal, and cutaneous malformations were also encountered. The uniform and highly characteristic features of the truncal lipomatous mass, in combination with vascular, acral, and other anomalies, provide evidence of a distinct nosologic and clinical entity. Morbid sequelae of the truncal involvement in this condition can be deforming and disabling; hence, prompt diagnosis and multidisciplinary care are necessary.

Congenital lipomatous overgrowth, vascular malformations, and epidermal nevi (CLOVE) syndrome: CNS malformations and seizures may be a component of this disorder

A newborn girl was found to have a massive lymphatic truncal vascular malformation with overlying cutaneous venous anomaly associated with overgrown feet and splayed toes. These manifestations comprise the recently described CLOVE syndrome. She also had cranial asymmetry and developed generalized seizures, which were treated with anticonvulsants. Cranial CT showed encephalomalacia, widening of the ventricles and the sulci, hemimegalencephaly (predominantly white matter) and partial agenesis of corpus callosum. Review of the literature identified several other patients with CLOVE syndrome, some of whom were misdiagnosed as having Proteus syndrome, with strikingly similar manifestations. We conclude that CNS manifestations including hemimegalencephaly, dysgenesis of the corpus callosum, neuronal migration defects, and the consequent seizures, may be an rarely recognized manifestation of CLOVE syndrome.

Newly delineated syndrome of congenital lipomatous overgrowth, vascular malformations, and epidermal nevi (CLOVE syndrome) in seven patients

We present a series of seven patients who were previously diagnosed with Proteus syndrome, but who do not meet published diagnostic criteria for this disorder and whose natural history is distinct from that of Proteus syndrome. This newly recognized phenotype comprises progressive, complex, and mixed truncal vascular malformations, dysregulated adipose tissue, varying degrees of scoliosis, and enlarged bony structures without progressive bony overgrowth. We have named this condition congenital lipomatous overgrowth, vascular malformations, and epidermal nevi (CLOVE syndrome) on a heuristic basis. In contrast to the bony distortion so characteristic of Proteus syndrome, distortion in CLOVE syndrome occurs only following major or radical surgery. Here, we contrast differences and similarities of CLOVE syndrome to Proteus syndrome.

Parenting children with Proteus syndrome: experiences with, and adaptation to, courtesy stigma

Courtesy stigma refers to the stigmatization an unaffected person experiences due to his or her relationship with a person who bears a stigma. Parents of children with genetic conditions are particularly vulnerable to courtesy stigma, but little research has been done to explore this phenomenon. The purpose of this study was to investigate the courtesy stigma experiences of parents of children with Proteus syndrome (PS) and related overgrowth conditions. Thematic analysis of transcripts from 31 parents identified three distinct themes: stigma experiences, social-emotional reactions to stigmatizing encounters, and coping responses. Four types of stigmatizing experiences were identified: intrusive inquires, staring and pointing, devaluing remarks, and social withdrawal. Additionally, we uncovered eight strategies parents used to cope with courtesy stigma: attributing cause, assigning meaning to social exchanges, concealing, withdrawing socially, taking the offensive, employing indifference, instructing and learning from family, and educating others. Parents' choices of strategy type were found to be context dependent and evolved over time. This is the first study to document the adaptive evolution of coping strategies to offset courtesy stigma by parents of children with genetic conditions. These results provide groundwork for genetic counseling interventions aimed at addressing issues of courtesy stigma and further investigation of the phenomenon itself.

Bone malformations in Proteus syndrome: an analysis of bone structural changes and their evolution during growth

The radiographic follow-up of a patient with Proteus syndrome is presented. Review of radiographs obtained at 3 years 10 months, 10 years, and 17 years 8 months indicated that the rate of growth in length of the oversized tubular bones of the hands was similar to that of the normal bones of the same hand. This observation supports the view that the primary lesion occurs in the early embryonic period, when the limb bud mesenchyme cells condense and cartilage differentiates producing oversized cartilage anlages, rather than being a defect of bone cell-mediated apposition and modelling processes of bone. Additional radiographs of the pelvis and spine were obtained at age 4 years 10 months and head CT at 8 years 10 months. This pathogenetic mechanism fits well with the hypothesis of somatic mosaicism, which is at present the most credible explanation for the aetiology of Proteus syndrome. Other skeletal malformations recognized as typical of the syndrome can be interpreted as secondary adaptations to the altered mechanical conditions induced by overgrowth of bones.

Vascular malformations. Part II: associated syndromes

Cutaneous vascular malformations are rare disorders representing errors in vascular development. These lesions occur much less commonly but are often confused with the common infantile hemangioma. It is important to properly diagnose vascular malformations because of their distinct differences in morbidity, prognosis and treatment. Vascular malformations may be associated with underlying disease or systemic anomalies. Several of these syndromes are well defined and can often be distinguished on the basis of the flow characteristics of the associated vascular malformation.

LEARNING OBJECTIVE

At the completion of this learning activity, participants should be able to better recognize underlying diseases or systemic anomalies that may be associated with vascular malformations. Participants should also better understand the various syndromes and conditions discussed and become more familiar with their management.

A female with hemihypertrophy and chylous ascites – Klippel–Trenaunay syndrome or Proteus syndrome: a diagnostic dilemma

Asymmetric overgrowth has many differential diagnoses with considerable overlap, posing a diagnostic dilemma. The presence of chylous ascites, though unreported, might be expected as a manifestation of overgrowth syndromes with lymphatic involvement. We present a patient with hemihypertrophy who presented with chylous ascites at birth.

The challenges of Proteus syndrome: diagnosis and management

Proteus syndrome (PS) is a disorder of patchy or mosaic postnatal overgrowth of unknown etiology. The onset of overgrowth typically occurs in infancy and can involve any tissue of the body. Commonly involved tissues include connective tissue and bone, skin, central nervous system, the eye, but it apparently can affect any tissue. Diagnosing of PS is difficult and the diagnostic criteria are controversial. Our group advocates stringent diagnostic criteria to facilitate research and appropriate clinical care. The benefit of strict criteria is that they define a clinical group that is reasonably homogenous with respect to manifestations and prognosis. The overgrowth of PS is progressive and can be difficult to manage. The progressive overgrowth most commonly causes severe orthopaedic complications, but it can cause many other complications. One of the most common complications in patients with PS is deep venous thrombosis and pulmonary embolism, which can cause premature death. Effective management requires knowledge of the wide array of manifestations and complications of the disorder and a team approach that includes the geneticist, surgeons, and other specialists.

Hemihyperplasia syndromes

OBJECTIVE

Hemihyperplasia is a heterogenous group of disorders characterized by asymmetric limb growth. There is considerable confusion regarding their classification and ascertainment into various syndromes. We tried to look into the various aspects of hemihyperplasia syndromes.

METHODS

Records of 17 consecutive cases of hemihyperplasia were reviewed and were ascertained into various syndromes based on available literature and diagnostic criteria.

RESULTS

Of the 17 cases with hemihyperplasia, 3 cases satisfied the diagnostic criteria for Proteus syndrome. One patient each was ascertained as Klippel Trenaunay Weber syndrome and Hemihyperplasia- Multiple lipomatosis. 9 cases were classified as isolated hemihyperplasia. We found two novel associations with hemihyperplasia; namely Ehlers-Danlos syndrome like skin changes and Poland anomaly on the affected side. The remaining 3 cases had miscellaneous disorders with limb asymmetry, namely Neurofibromatosis Type I in 2 cases and Olliers disease in one case.

CONCLUSION

Efforts to diagnose syndromes of hemihyperplasia help in genetic counseling.

Evolution of skin lesions in Proteus syndrome

BACKGROUND

Proteus syndrome is a rare overgrowth disorder that is generally progressive, but the natural history of the skin lesions is not known.

OBJECTIVE

Our purpose was to document the evolution of 4 common skin lesions in 16 patients with Proteus syndrome.

RESULTS

Most epidermal nevi and vascular malformations were reported to appear in the first month of life and had little tendency for expansion or development of additional lesions. Subcutaneous lipomas and cerebriform connective tissue nevi were commonly noted in the first year of life, but not in the first month. Most patients reported that subcutaneous lipomas and cerebriform connective tissue nevi progressively increased in size, and in most patients additional lesions developed at new locations. Of the 4 types of skin lesions, plantar cerebriform connective tissue nevi were most frequently cited as a source of symptoms.

CONCLUSION

Skin lesions of Proteus syndrome may not appear until later infancy or early childhood, making it difficult to diagnose in young children.

Proteus syndrome: a rare cause of hemihypertrophy and macrodactyly on bone scanning

Proteus syndrome is a rare, sporadic genetic disorder characterized by overgrowth of multiple different tissues in a mosaic pattern. It is associated with connective tissue nevi, epidermal nevi, disproportionate overgrowth of multiple tissues, vascular malformations, characteristic tumors, and specific facial anomalies. Joseph Merrick, popularly known as the Elephant Man, is now believed to have suffered from Proteus syndrome. A case of Proteus syndrome and associated findings on bone scintigraphy are presented.

Proteus syndrome: an update

Proteus syndrome is a complex disorder consisting variably of disproportionate, asymmetric overgrowth of body parts; cerebriform connective tissue nevi; epidermal nevi; vascular malformations of the capillary, venous, and lymphatic types; and dysregulated adipose tissue. Serious complications may ensue, such as pulmonary embolism, cystic lung disease, and various neoplasms. Somatic mosaicism, lethal in the nonmosaic state, is the best working hypothesis. Although Proteus syndrome data are consistent with this hypothesis, it has not been proven. The etiology is unknown to date. Diagnostic criteria are emphasized because misdiagnosis of Proteus syndrome is common. Finally, evaluation and management are discussed.

Reassessment of the Proteus syndrome literature: application of diagnostic criteria to published cases

The medical care of patients affected by rare disorders depends heavily on experiences garnered from prior cases, including those patients evaluated by the treating physician and those published in the medical literature. The utility of published cases is wholly dependent upon accurate diagnosis of those patients. In our experience, the rate of misdiagnosis in Proteus syndrome (PS) is high. Diagnostic criteria have been published, but these criteria have not been applied consistently and were published after many case reports appeared in the literature. We reviewed 205 cases of individuals reported to have PS in the literature and three of us independently applied the diagnostic criteria to these case reports. Our initial diagnostic congruence was 97.1% (199/205); the discrepancies in six cases were easily resolved. Only 97 (47.3%) of reported cases met the diagnostic criteria for PS; 80 cases (39%) clearly did not meet the criteria; and although 28 cases (13.7%) had features suggestive of PS, there were insufficient clinical data to make a diagnosis. Reported cases that met the PS criteria had a higher incidence of premature death, and other complications (scoliosis, megaspondyly, central nervous system abnormalities, tumors, otolaryngologic complications, pulmonary cystic malformations, dental and ophthalmogic complications) compared to those in the non-Proteus group. The cases that met the criteria were more often male, which has implications for hypotheses regarding the etiology and pathophysiology of PS. We also studied the attributes that led authors to conclude the reported patients had PS when we concluded they did not. We found that two of the diagnostic criteria (disproportionate overgrowth and connective tissue nevi) were often misinterpreted. In PS, the abnormal growth is asymmetric, distorting, relentless, and occurred at a faster rate compared to the rest of the body. Furthermore, PS was associated with irregular and disorganized bone, including hyperostoses, hyperproliferation of osteoid with variable calcification, calcified connective tissue, and elongation of long bones with abnormal thinning. In contrast, non-Proteus cases displayed overgrowth that was asymmetric but grew at a rate similar to the growth found in unaffected areas of the body. Also, the overgrowth in non-Proteus cases was associated with normal or enlarged bones together with ballooning of the overlying soft tissues. Taken together, these data show that (1) PS diagnostic criteria sort individuals with asymmetric overgrowth into distinct groups; (2) individuals with PS were more likely to have serious complications; (3) PS affects more males than females; and 4) the published diagnostic criteria are useful for clinical care and research. This article contains supplementary material, which may be viewed at the American Journal of Medical Genetics website at http://www.interscience.wiley.com/jpages/0148-7299/suppmat/index.html.

Mutation analysis of the tumor suppressor PTEN and the glypican 3 (GPC3) gene in patients diagnosed with Proteus syndrome

Proteus syndrome is a complex hamartomatous disorder characterized by asymmetrical gigantism, epidermal nevi, vascular malformations, hamartomas, lipomas, and hyperostosis. Since the syndrome was first described, many hypotheses have been proposed to explain its occurrence. The most plausible is Happle's somatic mosaic hypothesis, but no somatic mutations in candidate genes have been reported to be clearly involved in Proteus syndrome. However, germ-line PTEN mutations have been reported in patients with Proteus and in "Proteus-like disorders." Other studies of patients with Proteus syndrome have not supported these findings. In this study, affected and unaffected tissue from six patients diagnosed with Proteus syndrome were screened by direct sequencing of genomic DNA to determine if there might be an association between germ-line or somatic mutations in PTEN or GPC3 and the development of Proteus syndrome. No intra-exonic mutations were identified, indicating that neither PTEN nor GPC3 are likely to have major roles in the etiology of Proteus syndrome in our series of patients.

Non-syndromic hemihyperplasia in a male and his mother

We present two family members with non-syndromic hemihyperplasia (HHP), which developed in adolescence. We have reviewed reported familial cases of HHP and conclude that presentation is similar to sporadi cases and that all affected family members have been related through a maternal relative.

Somatic gene mutation and human disease other than cancer

While the focus of much mutation research is on germ-line mutation, somatic mutation is being found to be important in human disease. Neurofibromatosis 1 and McCune-Albright are disorders which are detected in the skin and other systems. The skin manifestations were essential for the demonstration of somatic mosaicism in neurofibromatosis 1, while analysis of blood DNA demonstrated somatic mutation in neurofibromatosis 2. Incontinentia pigmenti is also a disorder seen in skin and other tissues, but here it is the rare variant of the disorder in males, where it is usually lethal, that involves somatic mosaicism. Paroxysmal nocturnal hemoglobinuria is a disorder of the blood and cell separation of blood elements allows the demonstration of the somatic mosaicism. This review also discusses disorders in which somatic mosaicism, for mutations probably incompatible with life if the mutation had been germ-line, are likely to be involved. These include the Proteus syndrome, which involves both vascular tissues and bones, and two disorders which might be thought of as representing two subtypes of Proteus: Klippel-Trenaunay, which involves vascular tissues, and Maffuci, which involves bones. Embryonic mutations, which create mosaicism for both the soma and germ-line, are being increasingly found in a number of disorders and are discussed more briefly. Finally, reverse mutations involving the soma have been recently found in several disorders and such revertant mutations are also examined. While the review focuses on the clinical importance of somatic mutations, many of the mutations found to date are tabulated. It is too early to see if there is a different pattern of somatic mutation as compared to germ-line mutation. Although the parameters to allow careful quantitation are not yet available, it seems that the frequency of gene mutation in embryonic cells is not markedly different than that in the germ-line.

Principles for the surgical management of patients with Proteus syndrome and patients with overgrowth not meeting Proteus criteria

BACKGROUND

Proteus syndrome is a rare, sporadic disorder consisting of disproportionate overgrowth of multiple tissues, vascular malformations, and connective tissue or epidermal nevi. Patients with Proteus syndrome present with diverse and variable phenotypes because of the syndrome's mosaic pattern of distribution.

METHODS

Eighty patients with Proteus syndrome, satisfying published diagnostic criteria, and 51 patients with overgrowth not meeting Proteus criteria were identified from the literature. Three additional patients, one patient with Proteus syndrome and 2 patients with overgrowth, were treated at the author's institutions and are discussed in detail. All nonorthopedic and noncutaneous surgical interventions were reviewed.

RESULTS

Fourteen genitourinary, 9 gastrointestinal, and 5 otolaryngologic operations were performed on patients with Proteus syndrome. Six genitourinary, 5 gastrointestinal, and 2 otolaryngologic operations were performed on patients with overgrowth not meeting Proteus criteria. Eight patients with Proteus syndrome and 4 patients with overgrowth experienced thoracic manifestations, generally diffuse cystic pulmonary lesions, but only 1 of 12 underwent surgical treatment.

CONCLUSIONS

Patients with visceral manifestations of either Proteus syndrome or overgrowth not meeting Proteus criteria should be treated in a similar manner. Lesions involving the ovaries and testes, because of the high incidence of neoplasm, should be managed aggressively. Gastrointestinal and renal lesions may be managed conservatively with frequent follow-up to minimize abdominal explorations. All patients undergoing surgery should have a thorough preoperative assessment of their airway and pulmonary reserve because of the relatively high frequency of tonsillar hypertrophy and pulmonary cystic involvement.

Proteus syndrome in adulthood

Proteus syndrome is a very rare congenital condition comprising malformations and overgrowth of multiple sorts of tissue. It was described for the first time in 1979 and was termed Proteus syndrome in 1983. The authors describe a 37-year-old patient who was diagnosed initially as having Klippel-Trenaunay-Weber syndrome at the age of 10 years. The patient was operated for a major thoracic lymphatic malformation, which caused functional problems. The operation at older age for this large lymphatic malformation proved to be complex. In addition, the authors address the difficulties in diagnosing Proteus syndrome. Vascular malformations causing functional problems in adulthood require major surgical procedures with a high risk of postoperative complications.