Neuroimaging abnormalities in patients with Cowden syndrome: Retrospective single-center study

Neural cell competition sculpting brain from cradle to grave

Darwinian selection, operating within the cellular ecosystem of multicellular organisms, drives a pervasive surveillance mechanism of cell-cell competition that shapes tissue architecture and function. While cell competition eliminates suboptimal cells to ensure tissue integrity across various tissues, neuronal competition specifically sculpts neural networks to establish precise circuits for sensory, motor and cognitive functions. However, our understanding of cell competition across diverse neural cell types in both developmental and pathological contexts remains limited. Here, we review recent advances on the phenomenon, and mechanisms and potential functions of neural cell competition (NCC), ranging from neural progenitors, neurons, astrocytes and oligodendrocytes to microglia. Physiological NCC governs cellular survival, proliferation, arborization, organization, function and territorial colonization, whereas dysregulated NCC may cause neurodevelopmental disorders, accelerate aging, exacerbate neurodegenerative diseases and drive brain tumor progression. Future work that leverages cell competition mechanisms may help to improve cognition and curb diseases.

Update on Pediatric Surveillance Recommendations for PTEN Hamartoma Tumor Syndrome, DICER1-Related Tumor Predisposition, and Tuberous Sclerosis Complex

Phosphate and tensin homolog hamartoma tumor syndrome, DICER1-related tumor predisposition, and tuberous sclerosis complex are rare conditions, which each increases risk for distinct spectra of benign and malignant neoplasms throughout childhood and adulthood. Surveillance considerations for each of these conditions focus on patient and family education, early detection, and multidisciplinary care. In this article, we present updated surveillance recommendations and considerations for children and adolescents with phosphate and tensin homolog hamartoma tumor syndrome, DICER1-related tumor predisposition, and tuberous sclerosis complex and provide suggestions for further research in each of these conditions.

Cerebral dural arteriovenous fistulas in patients with PTEN-related hamartoma tumor syndrome

Central nervous system (CNS) dural arteriovenous fistulas (DAVF) have been reported in PTEN-related hamartoma tumor syndrome (PHTS). However, PHTS-associated DAVF remain an underexplored field of the PHTS clinical landscape. Here, we studied cases with a PTEN pathogenic variant identified between 2007 and 2020 in our laboratory (n = 58), and for whom brain imaging was available. Two patients had DAVF (2/58, 3.4%), both presenting at advanced stages: a 34-year-old man with a left lateral sinus DAVF at immediate risk of hemorrhage, and a 21-year-old woman with acute intracranial hypertension due to a torcular DAVF. Interestingly, not all patients had 3D TOF/MRA, the optimal sequences to detect DAVF. Early diagnosis of DAVF can be lifesaving, and is easier to treat compared to developed, proliferative, or complex lesions. As a result, one should consider brain MRI with 3D TOF/MRA in PHTS patients at genetic diagnosis, with subsequent surveillance on a case-by-case basis.

PTEN hamartoma tumor syndrome: Clinical and genetic characterization in pediatric patients

OBJECTIVE

The aim of this study was to provide a full characterization of a cohort of 11 pediatric patients diagnosed with PTEN hamartoma tumor syndrome (PHTS).

PATIENTS AND METHODS

Eleven patients with genetic diagnostic of PHTS were recruited between February 2019 and April 2023. Clinical, imaging, demographic, and genetic data were retrospectively collected from their hospital medical history.

RESULTS

Regarding clinical manifestations, macrocephaly was the leading sign, present in all patients. Frontal bossing was the most frequent dysmorphism. Neurological issues were present in most patients. Dental malformations were described for the first time, being present in 27% of the patients. Brain MRI showed anomalies in 57% of the patients. No tumoral lesions were present at the time of the study. Regarding genetics, 72% of the alterations were in the tensin-type C2 domain of PTEN protein. We identified four PTEN genetic alterations for the first time.

CONCLUSIONS

PTEN mutations appear with a wide variety of clinical signs and symptoms, sometimes associated with phenotypes which do not fit classical clinical diagnostic criteria for PHTS. We recommend carrying out a genetic study to establish an early diagnosis in children with significant macrocephaly. This facilitates personalized monitoring and enables anticipation of potential PHTS-related complications.

Early is Better: Report of a Cowden Syndrome

In the clinical practice, it is not common for pediatricians to visit children with overgrowth phenotype. When it happens, it is important to focus on the age of manifestations and research the pathogenic causes using appropriate genetic test. Cowden syndrome is one of these rare causes; it is an autosomal dominant genodermatosis characterized by multiple hamartomas of ectodermal, mesodermal, and endodermal origin. It is caused by loss of function mutations in the phosphatase and tensin homolog (PTEN) gene located on chromosome 10q23.1 Loss of function of the PTEN gene contributes to overgrowth and risk for a variety of cancers including breast, thyroid, endometrium, skin, kidneys, and colon. The early diagnosis of Cowden disease allows a careful monitoring of the patients who are facing the risk of cancer transformation, which is the principal complication of the condition.

Variants in PTEN Are Associated With a Diverse Spectrum of Cortical Dysplasia

BACKGROUND

Inactivating mutations in PTEN are among the most common causes of megalencephaly. Activating mutations in other nodes of the PI3K/AKT/MTOR signaling pathway are recognized as a frequent cause of cortical brain malformations. Only recently has PTEN been associated with cortical malformations, and analyses of their prognostic significance have been limited.

METHODS

Retrospective neuroimaging analysis and detailed chart review were conducted on 20 participants identified with pathogenic or likely pathogenic mutations in PTEN and a cortical brain malformation present on brain magnetic resonance imaging.

RESULTS

Neuroimaging analysis revealed four main cerebral phenotypes-hemimegalencephaly, focal cortical dysplasia, polymicrogyria (PMG), and a less severe category, termed "macrocephaly with complicated gyral pattern" (MCG). Although a high proportion of participants (90%) had neurodevelopmental findings on presentation, outcomes varied and were favorable in over half of participants. Consistent with prior work, 39% of participants had autism spectrum disorder and 19% of participants with either pure-PMG or pure-MCG phenotypes had epilepsy. Megalencephaly and systemic overgrowth were common, but other systemic features of PTEN-hamartoma tumor syndrome were absent in over one-third of participants.

CONCLUSIONS

A spectrum of cortical dysplasias is present in individuals with inactivating mutations in PTEN. Future studies are needed to clarify the prognostic significance of each cerebral phenotype, but overall, we conclude that despite a high burden of neurodevelopmental disease, long-term outcomes may be favorable. Germline testing for PTEN mutations should be considered in cases of megalencephaly and cortical brain malformations even in the absence of other findings, including cognitive impairment.

Coexisting lipomatous meningioma and glioblastoma in Cowden syndrome: A unique tumor association

Cowden syndrome (CS) is a rare hereditary hamartoma-cancer disorder related to germline mutations in the tumor suppressor phosphatase and tensin homolog (PTEN) gene. Association of CS with intracranial tumors, apart from Lhermitte-Duclos disease (LDD), is not well recognized. We present an exceptional instance of concomitant meningioma and glioblastoma in CS, the first case ever reported. Following a new-onset seizure, a 62-year-old male harboring the PTEN gene germline mutation c.334C > G was diagnosed with multiple brain tumors, which were erroneously thought to correspond to metastases. Because no primary cancer was found, an operation was proposed for histopathological diagnosis. Examination of surgical specimens obtained from the two lesions removed, one extra-axial and the other intracerebral, demonstrated a metaplastic meningioma with a lipomatous appearance and an isocitrate dehydrogenase wild-type glioblastoma, respectively. Loss of the PTEN gene expression was demonstrated immunohistochemically in both lesions, a finding that supports their relation to CS. A thorough literature review revealed only 25 additional CS patients with intracranial tumors other than LDD. All of them corresponded to primary lesions, with meningiomas accounting for 76% of the cases (19 patients), followed by pituitary tumors (three cases) and glioblastomas (two patients from the same family). Our report and literature review highlight the association between CS and primary brain tumors rather than metastasis. For judicious management of a CS patient with multiple intracranial tumors, different primary brain pathological entities should also be suspected first before considering metastasis. Close neurological monitoring and brain magnetic resonance imaging are advocated as part of the cancer screening in CS patients, particularly in cases with a family history of intracranial tumors.

Impaired social cognition and fine dexterity in patients with Cowden syndrome associated with germline PTEN variants

PURPOSE

Cowden syndrome (CS) is an autosomal dominant disease related to germline PTEN variants and is characterised by multiple hamartomas, increased risk of cancers and frequent brain alteration. Since the behaviour of patients with CS sometimes appears to be inappropriate, we analysed their neuropsychological functioning.

METHODS

This monocentric study was conducted between July 2018 and February 2020. A standardised neuropsychological assessment, including an evaluation of social cognition, executive functions, language and dexterity, as well as a cerebral MRI were systematically proposed to all patients with CS. Moreover, PTEN variants were identified.

RESULTS

Fifteen patients from 13 families were included, with six non-sense (40%), three missense (20%), five frameshift (33.3%) and one splice site (6.6%) variant types. Twelve patients (80%) had altered social cognition: 10 patients had an abnormal modified Faux-Pas score and 5 had Ekman's facial emotions recognition impairment. Nearly all patients (93%) had impaired dexterity. Cerebral MRI showed various cerebellar anomalies in seven patients (46.7%).

CONCLUSION

Altered social cognition and impaired fine dexterity are frequently associated with CS. Further studies are needed to confirm these results and to determine whether dexterity impairment is due to the effect of germline PTEN variants in the cerebellum.

A progressive and refractory case of breast cancer with Cowden syndrome

BACKGROUND

Cowden syndrome is a rare autosomal-dominant disease with a high risk of malignant tumors of the breast, commonly caused by germline mutations in the PTEN gene. Most breast cancers related to Cowden syndrome showed typically a slow-growing and favorable clinical course. Here, we report a progressive case of triple-negative breast cancer in a patient who was diagnosed with Cowden syndrome.

CASE PRESENTATION

A 35-year-old female with breast cancer was referred to our hospital. Histopathological examination of the tumor showed that it was triple-negative breast cancer with high proliferation marker. Preoperative positron emission tomography-computed tomography showed abnormal uptake in the left cerebellar hemisphere in addition to the right breast and axillary lymph node. Brain T2-weighted magnetic resonance imaging revealed hyperintense bands in the left cerebellar hemisphere lesion, which demonstrated a "tiger-stripe" appearance. The patient's mother had died of endometrial cancer. Subsequently, she underwent genetic testing, leading to a diagnosis of Cowden syndrome with a pathogenic variant c.823_840del.18 at exon 8 in PTEN. She was treated with neoadjuvant chemotherapy of eribulin and cyclophosphamide followed by adriamycin and cyclophosphamide. However, her tumors increased after these treatments. She was immediately surgically treated and received adjuvant chemotherapy of capecitabine. Unfortunately, the cancer recurred in the lung nine months after surgery. We then administered paclitaxel and bevacizumab therapy, but the disease rapidly progressed. Consequently, the patient died due to breast cancer about three months after recurrence.

CONCLUSION

We report an aggressive case of cancer with Cowden syndrome which was resistant to standard chemotherapy. Alteration of the phosphatidylinositol-3 kinase/Akt/mammalian target of rapamycin pathway due to inactivating PTEN protein may be associated with chemoresistance and serves as a candidate for therapeutic intervention in PTEN-related cancers.

Formation of a de novo intracranial arteriovenous fistula in a child with PTEN hamartoma tumor syndrome

PURPOSE

Dural arteriovenous fistulae (dAVF) are an uncommon feature of PTEN hamartoma tumor syndrome (PHTS). We report a case of an adolescent male diagnosed with PHTS following the treatment of multiple intracranial dAVF to emphasize the association of vascular anomalies with this disorder and discuss potential implications.

CASE REPORT

An adolescent male presented with bilateral proptosis secondary to intracranial venous hypertension. Workup revealed the presence of a complex intracranial dAVF which was treated with several embolization procedures. Following treatment, a de novo dAVF was identified on surveillance imaging. A genetic workup revealed a pathogenic mutation in PTEN consistent with a diagnosis of PHTS.

CONCLUSIONS

Recognition that PHTS may be associated with dAVF, and potentially delayed spontaneous formation of dAVF, is critically important due to the potential for devastating yet preventable neurologic sequelae.

Developmental venous anomalies are a genetic primer for cerebral cavernous malformations

Cerebral cavernous malformations (CCM) are a neurovascular anomaly that may occur sporadically, or be inherited due to autosomal dominant mutations in KRIT1 , CCM2 , or PDCD10 . Individual lesions are caused by somatic mutations which have been identified in KRIT1, CCM2, PDCD10, MAP3K3, and PIK3CA . However, the interactions between mutations, and their relative contributions to sporadic versus familial cases remain unclear. We show that mutations in KRIT1, CCM2, PDCD10, and MAP3K3 are mutually exclusive, but may co-occur with mutations in PIK3CA. We also find that MAP3K3 mutations may cause sporadic, but not familial CCM. Furthermore, we find identical PIK3CA mutations in CCMs and adjacent developmental venous anomalies (DVA), a common vascular malformation frequently found in the vicinity of sporadic CCMs. However, somatic mutations in MAP3K3 are found only in the CCM. This suggests that sporadic CCMs are derived from cells of the DVA which have acquired an additional mutation in MAP3K3 .

Brain 18F-FDG PET in Cowden Syndrome

ABSTRACT

Cowden disease is associated with neurodevelopmental abnormalities such as macrocephaly, autism spectrum disorder, and developmental delay. Our understanding of neuroimaging anomalies in patients with PTEN mutations is limited to anatomical MRI abnormalities including white matter abnormalities, meningiomas, arteriovenous malformations, and cortical dysplasia. Our current communication extends the neurological Cowden syndrome phenotype by using brain 18F-FDG PET/CT imaging as a useful complementary approach to MRI to explore movement disorders and neuropsychiatric syndromes in a patient with Cowden disease. Brain 18F-FDG PET/CT showed diffuse hypometabolism of the prefrontal mesial and dorsolateral areas including supplementary motor areas, the pons extended to the cerebellum.

OUP accepted manuscript

Paediatric intracranial dural arteriovenous shunts have clinical presentations and evolutions, with angiographic characteristics that differ from those described in adults. We report our experience concerning their therapeutic management, emphasizing the relevance of early diagnosis and appropriate treatment for satisfactory neurocognitive development. Using a prospective database, we reviewed the clinical and radiological data of all children with dural arteriovenous shunts managed between 2002 and 2020. Dural shunts were categorized into three types: dural sinus malformations with arteriovenous shunts; infantile dural arteriovenous shunts; and adult-type dural arteriovenous shunts. Therapeutic strategies and outcomes were analysed depending on lesional subtypes. Modified Rankin Scale for the paediatric population was assessed pre-treatment and at last follow-up. Twenty-eight patients [16 girls (57.1%); 12 boys (42.9%)] were included: 17 dural sinus malformation [10 boys (58.8%); seven girls (41.2%)], three infantile shunts [three girls (100%)], eight adult-type shunts [four girls (50%)]; four boys (50%)], with a mean age of 19.2 ± 36.6 months at presentation. Twelve (42.9%) had a modified Rankin Scale score of 0–2, four (14.3%) had a score of 3, three (10.7%) had a score of 4 and eight (28.6%) had a score of 5. Embolization was performed in 22 children [78.6%; 12 girls (54.5%); 10 boys (45.5%)]. Fifteen patients could be cured (68.2%): 11 dural sinus malformations (73.3%), four adult-type lesions (100%) but no infantile shunt. Mean post-treatment follow-up was 39.5 months (max. 139 months): 14 patients (63.6%) presented a modified Rankin Scale score of 0–2 and eight (36.4%) had a score ≥3. In the dural sinus malformation group, the modified Rankin Scale score was improved in 11 patients (73.3%) and unchanged in three (20%). Only one patient with infantile subtype (33.3%) improved clinically. In the adult-subtype group, all children (100%) improved. Of six untreated patients [four girls (66.7%); two boys (33.3%)], four with adult-subtype shunts showed uneventful evolutions, one with dural sinus malformation died, and therapeutic abortion was conducted in an antenatally diagnosed dural sinus malformation. Paediatric dural fistulas comprise different subtypes with variable clinical courses. Proper diagnosis is mandatory for optimal therapeutic strategies within appropriate therapeutic windows.

The Forgotten Phacomatoses: A Neuroimaging Review of Rare Neurocutaneous Disorders

Phakomatoses, or neurocutaneous syndromes, are a heterogeneous group of rare genetic disorders that predominantly affect structures arising from the embryonic ectoderm, namely the skin, eye globe, retina, tooth enamel, and central nervous system. Other organs are also involved in some syndromes, mainly cardiovascular, pulmonary, renal, and musculoskeletal systems. Currently, more than sixty distinct entities belonging to this category have been described in the literature. Common phakomatoses include conditions like Neurofibromatosis and Tuberous sclerosis. Several review papers have focused on various aspects of these common conditions, including clinical presentation, genetic and molecular basis, and neuroimaging features. In this review, we focus on rare neurocutaneous syndromes: Melanophakomatoses (Ie, Neurocutaneous Melanosis, and Incontinentia Pigmenti), Vascular Phakomatoses (Ie, Ataxia Telangiectasia and PHACE Syndrome), and other conditions such as Cowden Syndrome, Basal Nevus Syndrome, Schwannomatosis, Progressive Facial Hemiatrophy, Gomez-Lopez-Hernandez Syndrome, Wyburn-Mason Syndrome, CHILD Syndrome, and Proteus Syndrome. We also review the neuroradiologic manifestations of these conditions as a guide for neurologists and neuroradiologists in their daily practice.

Diagnostic Approach to Macrocephaly in Children

Macrocephaly affects up to 5% of the pediatric population and is defined as an abnormally large head with an occipitofrontal circumference (OFC) >2 standard deviations (SD) above the mean for a given age and sex. Taking into account that about 2-3% of the healthy population has an OFC between 2 and 3 SD, macrocephaly is considered as "clinically relevant" when OFC is above 3 SD. This implies the urgent need for a diagnostic workflow to use in the clinical setting to dissect the several causes of increased OFC, from the benign form of familial macrocephaly and the Benign enlargement of subarachnoid spaces (BESS) to many pathological conditions, including genetic disorders. Moreover, macrocephaly should be differentiated by megalencephaly (MEG), which refers exclusively to brain overgrowth, exceeding twice the SD (3SD-"clinically relevant" megalencephaly). While macrocephaly can be isolated and benign or may be the first indication of an underlying congenital, genetic, or acquired disorder, megalencephaly is most likely due to a genetic cause. Apart from the head size evaluation, a detailed family and personal history, neuroimaging, and a careful clinical evaluation are crucial to reach the correct diagnosis. In this review, we seek to underline the clinical aspects of macrocephaly and megalencephaly, emphasizing the main differential diagnosis with a major focus on common genetic disorders. We thus provide a clinico-radiological algorithm to guide pediatricians in the assessment of children with macrocephaly.

Polymicrogyria is Associated With Pathogenic Variants in PTEN

OBJECTIVE

Congenital structural brain malformations have been described in patients with pathogenic phosphatase and tensin homologue (PTEN) variants, but the frequency of cortical malformations in patients with PTEN variants and their impact on clinical phenotype are not well understood. Our goal was to systematically characterize brain malformations in patients with PTEN variants and assess the relevance of their brain malformations to clinical presentation.

METHODS

We systematically searched a local radiology database for patients with PTEN variants who had available brain magnetic resonance imaging (MRI). The MRI scans were reviewed systematically for cortical abnormalities. We reviewed electroencephalogram (EEG) data and evaluated the electronic medical record for evidence of epilepsy and developmental delay.

RESULTS

In total, we identified 22 patients with PTEN pathogenic variants for which brain MRIs were available (age range 0.4-17 years). Twelve among these 22 patients (54%) had polymicrogyria (PMG). Variants associated with PMG or atypical gyration encoded regions of the phosphatase or C2 domains of PTEN. Interestingly, epilepsy was present in only 2 of the 12 patients with PMG. We found a trend toward higher rates of global developmental delay (GDD), intellectual disability (ID), and motor delay in individuals with cortical abnormalities, although cohort size limited statistical significance.

INTERPRETATION

Malformations of cortical development, PMG in particular, represent an under-recognized phenotype associated with PTEN pathogenic variants and may have an association with cognitive and motor delays. Epilepsy was infrequent compared to the previously reported high risk of epilepsy in patients with PMG. ANN NEUROL 2020;88:1153-1164.

Cowden syndrome is a risk factor for multiple neoplasm: a case report

BACKGROUND

Cowden's syndrome is an autosomal dominant disease with variable penetrance, involving the tumor suppressor phosphatase and tension homolog gene, located on chromosome 10q22-23, responsible for cell proliferation, migration, and cellular apoptosis. Its clinical presentation encompasses mucocutaneous lesions, which are present around 99% of the time; macrocephaly; and cognitive impairment, and it precedes the appearance of neoplasms such as thyroid carcinoma, breast cancer, among others. In addition to these malformations, arteriovenous malformations of the brain and spine, endocrine abnormalities, skeletal defects, and cardiopulmonary lesions may also be found. The relevance of the case is due to the fact that, through a certain phenotype, the patient's genotype can be inferred and thus followed up closely.

CASE REPRESENTATION

The clinical case concerns a 28-year-old Caucasian and Portuguese woman with palmar pits, macrocephaly, and cognitive impairment. She was diagnosed with papillary thyroid carcinoma at 22 years of age and proposed total thyroidectomy. At age 27, a pregnancy was diagnosed with a Breast Imaging-Reporting and Data System 2-rated breast lump. After the histological verification, it was concluded that it was a high metastatic breast sarcoma, opting for palliative mastectomy. A genetic evaluation confirmed alteration in the phosphatase and tension homolog gene, confirming Cowden's syndrome. The patient died at age 29 due to neoplastic pathology.

CONCLUSION

This report aims to alert to the clinical signs of this entity and the clinical supervision and follow-up of these patients. In order to prevent premature deaths and to improve patient's quality of life, genetic diseases with cancer impact should be diagnosed as early as possible.

Cerebral MRI and Clinical Findings in Children with PTEN Hamartoma Tumor Syndrome: Can Cerebral MRI Scan Help to Establish an Earlier Diagnosis of PHTS in Children?

Background: PTEN Hamartoma Tumor Syndrome (PHTS) is caused by germline autosomal-dominant mutations of the tumor suppressor gene PTEN. Subjects harbour an increased risk for tumor development, with thyroid carcinoma occurring in young children. Establishing a diagnosis is challenging, since not all children fulfill diagnostic criteria established for adults. Macrocephaly is a common feature in childhood, with cerebral MRI being part of its diagnostic workup. We asked whether distinct cMRI features might facilitate an earlier diagnosis. Methods: We retrospectively studied radiological and clinical data of pediatric patients who were presented in our hospital between 2013 and 2019 in whom PTEN gene mutations were identified. Results: We included 27 pediatric patients (18 male) in the analysis. All patients were macrocephalic. Of these, 19 patients had received at least one cMRI scan. In 18 subjects variations were detected: enlarged perivascular spaces (EPVS; in 18), white matter abnormalities (in seven) and less frequently additional pathologies. Intellectual ability was variable. Most patients exhibited developmental delay in motor skills, but normal intelligence. Conclusion: cMRI elucidates EPVS and white matter abnormalities in a high prevalence in children with PHTS and might therefore aid as a diagnostic feature to establish an earlier diagnosis of PHTS in childhood.

Symptomatic developmental venous anomalies

Cerebral developmental venous anomalies (DVAs) are variations of venous vascular anatomy related to an underdevelopment of either the superficial or deep venous emissary system, resulting in a dilated transmedullary vein fed by multiple smaller venous radicles responsible for drainage of normal brain parenchyma. While typically benign and found incidentally on imaging studies, DVAs can rarely be symptomatic. The radiographic appearance of DVAs, as well as their symptomatic manifestations, is diverse. Herein, we will discuss the pathophysiology of symptomatic DVAs while providing illustrative case examples depicting each of their pathogenic mechanisms.

Imaging of PTEN-related abnormalities in the central nervous system

The phosphatase and tensin homolog (PTEN) located at 10q23.31 is a tumor suppressor gene expressed ubiquitously, and loss of function mutations lead to aberrant growth, angiogenesis, and an increased risk for a variety of tumors. PTEN mutations have been associated with multiple abnormalities in the central nervous system, and a number of clinical phenotypes are now attributed to germline PTEN mutations, collectively referred to as PTEN hamartoma tumor syndrome (PHTS). Most notably, these include Cowden syndrome (CS), Bannayan-Riley-Ruvalcaba syndrome (BRRS), and autism spectrum disorders with macrocephaly. It is important to recognize the neuroimaging features associated with PTEN mutations to not only avoid misdiagnosis in cases of known PHTS but also to guide genetic testing in patients who do not yet have an established diagnosis. In this review, the central nervous system imaging features of PTEN-related disorders are discussed.

PTEN Hamartoma tumor syndrome in childhood: A review of the clinical literature

PTEN hamartoma tumor syndrome (PHTS) is a highly variable autosomal dominant condition associated with intellectual disability, overgrowth, and tumor predisposition phenotypes, which often overlap. PHTS incorporates a number of historical clinical presentations including Bannayan-Riley-Ruvalcaba syndrome, Cowden syndrome, and a macrocephaly-autism/developmental delay syndrome. Many reviews in the literature focus on PHTS as an adult hamartoma and malignancy predisposition condition. Here, we review the current literature with a focus on pediatric presentations. The review starts with a summary of the main conditions encompassed within PHTS. We then discuss PHTS diagnostic criteria, and clinical features. We briefly address rarer PTEN associations, and the possible role of mTOR inhibitors in treatment. We acknowledge the limited understanding of the natural history of childhood-onset PHTS as a cancer predisposition syndrome and present a summary of important management considerations.

The Clinical Spectrum of PTEN Mutations

PTEN is a tumor suppressor gene that classically dampens the PI3K/AKT/mTOR growth-promoting signaling cascade. PTEN dysfunction causes dysregulation of this and other pathways, resulting in overgrowth. Cowden syndrome, a hereditary cancer predisposition and overgrowth disorder, was the first Mendelian condition associated with germline PTEN mutations. Since then, significant advances by the research and medical communities have elucidated how clinical phenotypic manifestations result from the underlying germline PTEN mutations. With time, it became evident that PTEN mutations can result in a broad phenotypic spectrum, causing seemingly disparate disorders from cancer to autism. Hence, the umbrella term of PTEN hamartoma tumor syndrome (PHTS) was coined. Timely diagnosis and understanding the natural history of PHTS are vital because early recognition enables gene-informed management, particularly as related to high-risk cancer surveillance and addressing the neurodevelopmental symptoms.