A Case of Noonan Syndrome and Kyrle's Disease: Coincidence or Causality?

A 39-year-old Caucasian woman affected by Noonan Syndrome (NS) mutated in RAF1 was referred to us with itchy lesions on her limbs that had appeared two months earlier. Clinically, there were multiple umbilicated papules with a hyperkeratotic central plug, localized on the upper and lower limbs (Figure 1, a-b). The patient had no personal history of diabetes mellitus and no chronic renal failure, but suffered from hypertrophic cardiomyopathy. Blood tests showed no abnormalities. On histological examination of a skin lesion, an ectatic hair follicle with hyperkeratotic ostium was observed with fragments of hair, inflammatory cells, and epidermal perforation. A final diagnosis of Kyrle's disease (KD) was established. The patient underwent narrowband UVB (NB-UVB) phototherapy with residual atrophic scars (Figure 1, c-d) but with complete and long-lasting resolution of symptoms as well. KD belongs to perforating dermatoses (PD), a heterogeneous group of skin diseases characterized by the transepidermal elimination of dermal components. Despite the classification of PD being debated, four primary forms are traditionally recognized: reactive perforating collagenosis, elastosis perforans serpiginosum, perforating folliculitis, and KD (1). The typical skin manifestation of KD is an eruption of dome-shaped papules and nodules with a whitish central keratotic plug, mainly localized on the extremities and the buttocks. Described by Kyrle in 1916, KD is frequently associated with systemic diseases, especially chronic renal failure and diabetes mellitus. Other associated conditions include chronic hepatic disease, internal malignancies, and congestive heart disease (1). Despite the absence of a consensus, the control of the underlying disease remains the first therapeutic target. Both topical (keratolytics, retinoids, and corticosteroids) and systemic treatments (corticosteroid, retinoids, antibiotics, and phototherapy) have been reported to control skin manifestations (2). In our experience, NB-UVB is an effective option as first-line therapy in case of diffuse lesions, both in KD and in other PDs (3). NS is a relatively common RASopathy, an heterogenous group of genetic disease characterized by a defect of the Ras-mitogen-activated protein kinase (Ras-MAPK) pathway, with an estimated prevalence of 1/1000-2500. PTPN11 is the most frequent mutated gene, accounting for 50% of cases, but more than ten genes were identified as causing NS (4). Classical features include a distinctive facial dysmorphism, short stature, pulmonic stenosis, and other anomalies of different organs. The skin is commonly involved. Keratinization disorders and hair abnormalities such as keratosis pilaris, ulerythema ophryogenes, wavy or curly hair, and scarce scalp hair are often described. Other cutaneous signs include easy bruising, skin hyperlaxity, multiple lentigines, and café-au-lait spots (5). To the best of our knowledge, no cases of KD in patients with NS have been previously reported to date. The exact etiopathogenesis of KD is not clear, but it was hypothesized that systemic diseases, such as diabetes and chronic renal failure, can cause a deposit of substances or dermis alterations, which triggers the inflammatory process with subsequent transepidermal extrusion (1). In our patient, we ruled out all the causes commonly associated with KD. It is however possible that this manifestation could be a direct result of our patient's illness. Our patient suffered from diffuse keratosis pilaris, and one of the possible pathogenetic mechanisms of KD was theorized to be an abnormal epidermal keratinization with a secondary inflammatory dermic response (1). On the other hand, the hyperlaxity and fragility of the skin typical of NS suggest the presence of altered connective tissue, which could trigger an abnormal keratinization and, subsequently, the transepidermal extrusion, as well as perforating elastosis, and is associated with genetic connective tissue diseases (1). Moreover, our patient suffered from a cardiac disease, another condition associated with KD (5). Although these explanations have their appeal, there is currently insufficient evidence of a link between KD and NS, and it will be necessary to collect additional data to confirm this hypothesis.

Hyperbaric oxygen treatment in bilateral orchiopexy and post-circumcision haematoma in a thrombocytopenic patient with Noonan syndrome.

Hyperbaric oxygen treatment (HBOT) can be utilised for necrotising soft tissue infections, clostridial myonecrosis (gas gangrene), crush injuries, acute traumatic ischaemia, delayed wound healing, and compromised skin grafts. Our case was a 17-month-old male patient with Noonan syndrome, idiopathic thrombocytopenic purpura, and bilateral undescended testicles. Haematoma and oedema developed in the scrotum and penis the day after bilateral orchiopexy and circumcision. Ischaemic appearances were observed on the penile and scrotal skin on the second postoperative day. Enoxaparin sodium and fresh frozen plasma were started on the recommendation of haematology. Hyperbaric oxygen treatment was initiated considering the possibility of tissue necrosis. We observed rapid healing within five days. We present this case to emphasise that HBOT may be considered as an additional treatment option in patients with similar conditions. To our knowledge, no similar cases have been reported in the literature.

Cardiac screening in pediatric patients with neurofibromatosis type 1: similarities with Noonan syndrome?

Both Neurofibromatosis type 1 (NF1) and Noonan syndrome (NS) are RASopathies. Characteristic cardiac phenotypes of NS, including specific electrocardiographic changes, pulmonary valve stenosis and hypertrophic cardiomyopathy have not been completely studied in NF1. PURPOSE: The aims of this study were to assess: (1) similarities in the prevalence and types of ECG and conventional echocardiographic findings described in NS in asymptomatic patients with NF1, and (2) the presence of discrete myocardial dysfunction in NF1 patients using myocardial strain imaging. METHODS: Fifty-eight patients with NF1 (ages 0-18 years), and thirty-one age-matched healthy controls underwent cardiac assessment including blood pressure measurements, a 12-lead ECG, and detailed echocardiography. Quantification of cardiac chamber size, mass and function were measured using conventional echocardiography. Myocardial strain parameters were assessed using 2-Dimensional (2D) Speckle tracking echocardiography. RESULTS: Asymptomatic patients with NF1 had normal electrocardiograms, none with the typical ECG patterns described in NS. However, patients with NF1 showed significantly decreased calculated Z scores of the left ventricular internal diameter in diastole and systole, reduced left ventricular mass index and a higher incidence of cardiac abnormal findings, mainly of the mitral valve, in contrast to the frequently described types of cardiac abnormalities in NS. Peak and end systolic global circumferential strain were the only significantly reduced speckle tracking derived myocardial strain parameter. CONCLUSIONS: Children with NF1 demonstrated more dissimilarities than similarities in the prevalence and types of ECG and conventional echocardiographic findings described in NS. The role of the abnormal myocardial strain parameter needs to be explored.

Gonadal dysfunction in a man with Noonan syndrome from the LZTR1 variant: case report and review of literature.

Noonan syndrome (NS) is a genetic disorder characterized by multiple congenital defects caused by mutations in the RAS/mitogen-activated protein kinase pathway. Male fertility has been reported to be impaired in NS, but only a few studies have focused on fertility status in NS patients and underlying mechanisms are still incompletely understood. We describe the case of a 35-year-old man who underwent an andrological evaluation due to erectile dysfunction and severe oligospermia. A syndromic facial appearance and reduced testis size were present on clinical examination. Hormonal evaluation showed normal total testosterone level, high FSH level, and low-normal AMH and inhibin B, compatible with primary Sertoli cell dysfunction. Genetic analysis demonstrated the pathogenetic heterozygous variant c.742G>A, p.(Gly248Arg) of the LZTR1 gene (NM_006767.3). This case report provides increased knowledge on primary gonadal dysfunction in men with NS and enriches the clinical spectrum of NS from a rare variant in the novel gene LZTR1.

Dermatological manifestations in Costello syndrome: A prospective multicentric study of 31 HRAS-positive variant patients.

BACKGROUND: Data on dermatological manifestations of Costello syndrome (CS) remain heterogeneous and lack in validated description. OBJECTIVES: To describe the dermatological manifestations of CS; compare them with the literature findings; assess those discriminating CS from other RASopathies, including cardiofaciocutaneous syndrome (CFCS) and the main types of Noonan syndrome (NS); and test for dermatological phenotype-genotype correlations. METHODS: We performed a 10-year, large, prospective, multicentric, collaborative dermatological and genetic study. RESULTS: Thirty-one patients were enrolled. Hair abnormalities were ubiquitous, including wavy or curly hair and excessive eyebrows, respectively in 68% and 56%. Acral excessive skin (AES), papillomas and keratotic papules (PKP), acanthosis nigricans (AN), palmoplantar hyperkeratosis (PPHK) and 'cobblestone' papillomatous papules of the upper lip (CPPUL), were noted respectively in 84%, 61%, 65%, 55% and 32%. Excessive eyebrows, PKP, AN, CCPUL and AES best differentiated CS from CFCS and NS. Multiple melanocytic naevi (>50) may constitute a new marker of attenuated CS associated with intragenic duplication in HRAS. Oral acitretin may be highly beneficial for therapeutic management of PPHK. No significant dermatological phenotype-genotype correlation was determined between patients with and without HRAS c.34G>A (p.G12S). CONCLUSIONS AND RELEVANCE: This validated phenotypic characterization of a large number of patients with CS will allow future researchers to make a positive diagnosis, and to differentiate CS from CFCS and NS.

Syndromic and single gene disorders associated with fetal pleural effusion (I): Noonan syndrome, RASopathy and congenital lymphatic anomalies.

Fetal pleural effusion has been reported to be associated with chromosomal abnormalities, genetic syndromes, obstructive uropathy, lymphatic vessel abnormalities such as Noonan syndrome, RASopathy and congenital lymphatic anomalies, thoracic cavity defects, Rh or ABO incompatibility, non-immune hydrops fetalis, infections, congenital cardiac anomalies, metabolic diseases and hematologic diseases such as α-thalassemia. This review provides an overview of syndromic and single gene disorders associated with fetal pleural effusion that is useful for genetic counseling and fetal therapy at prenatal diagnosis of fetal pleural effusion.

Congenital ectropion in Noonan syndrome.

Ten-year-old female patient, with facial dysmorphia, scoliosis, short stature, muscular hypotonia, patent foramen ovale and maturational delay, presented for correction of bilateral congenital ectropion. Ophthalmological examination revealed bilateral lower eyelid ectropion, euryblepharon and lagophthalmos, with a positive Bell's phenomenon. She was treated with full-thickness autologous skin grafts on the lower eyelids with bilateral lateral canthoplasty, resolving the ectropion and improving eyelid occlusion. Subsequently, a genetic study was performed that revealed a mutation in the PTPN11 gene and allowed, together with the clinical picture, to make the diagnosis of Noonan syndrome. Noonan syndrome is a multisystem genetic disorder with a wide variety of phenotypes, which usually presents with ocular and periocular disorders. Eyelid ectropion, a distinctive feature of this patient, is a rare ophthalmological manifestation of this syndrome that can be corrected with full-thickness skin graft and lateral canthoplasty.

A case of systemic lupus erythematosus in a patient with Noonan syndrome with recurrent severe hypoglycaemia.

Noonan syndrome (NS) is a dominantly inherited genetic disorder with mutations in genes encoding components or regulators of the Rat sarcoma virus/mitogen-activated protein kinase pathway. Its diagnosis is based on characteristic features, including typical facial features, a short stature, congenital heart disease, mild developmental delay, and cryptorchidism. Patients with NS sometimes develop autoimmune diseases, such as Hashimoto's thyroiditis and, rarely, systemic lupus erythematosus (SLE). We herein present a 29-year-old Japanese female with NS complicated by SLE and repeated severe hypoglycaemia. The patient was diagnosed with SLE based on thrombocytopenia, nephritis, a positive antinuclear antibody titre (1:640), and a positive anti-dsDNA antibody. The patient was treated with a glucocorticoid, mycophenolate mofetil, and tacrolimus, which attenuated both SLE and hypoglycaemia. Since insulin receptor antibody levels were higher to the upper normal range and decreased after treatment, hypoglycaemia probably appeared to be attributed to type B insulin resistance syndrome. We herein present the first case of SLE in NS complicated by type B insulin resistance syndrome. Although NS is a rare disease, we need to consider the complication of autoimmune diseases, including SLE.

Monogenic systemic lupus erythematosus onset in a 13-year-old boy with Noonan like-syndrome: a case report and literature review.

BACKGROUND: Childhood systemic lupus erythematosus (cSLE) has been considered as a polygenic autoimmune disease; however, a monogenic lupus-like phenotype is emerging with the recent recognition of several related novel high-penetrance genetic variants. RASopathies, a group of disorders caused by mutations in the RAS/MAPK pathway, have been recently described as a cause of monogenic lupus. CASE PRESENTATION: We present a 13-year-old boy with Noonan-like syndrome with loose anagen hair who developed a monogenic lupus. The renal biopsy confirmed a class III lupus nephritis and identified the presence of zebra bodies. CONCLUSIONS: RASopathies represent a cause of monogenic lupus. We report a new case of monogenic lupus in a child with Noonan-like syndrome with loose anagen hair. Lupus nephritis which has never been described in this context, may be part of the presentation. The presence of zebra bodies in SLE or RASopathies in unclear, but no other known conditions (Fabry disease or drugs) were identified as the cause of zebra bodies in our patient.

Central giant cell granuloma: Off-label treatment with Denosumab in a patient with Noonan syndrome.

This study aims to describe the utilization of Denosumabࣨ, a human monoclonal antibody against the RANK-L receptor, in a mandibular giant cell granuloma (GCG) with a significant local aggressiveness component that was unresponsive to surgical treatment. We present a case of a 19-year-old male patient diagnosed with Noonan syndrome, who presented a multifocal giant cell granuloma with aggressive behaviour resistant to surgical treatment. Due to the functional and aesthetic implications associated with a surgical procedure, a decision was made to initiate medical treatment using Denosumabࣨ. Throughout the treatment, the patient presented excellent clinical and analytical tolerance, with no reported adverse effects. Surgical intervention remains the preferred approach for GCG. Denosumabࣨ emerges as an alternative, either as neoadjuvant treatment or as definitive therapy for unresectable or resectable tumors associated with significant morbidity. It leads to size stabilization and regression of the tumour stage.

Differentiating primary sarcomeric hypertrophic cardiomyopathy from Noonan syndrome: can the electrocardiogram be of use?

Noonan syndrome is a multi-system genetic disorder and patients may suffer from hypertrophic cardiomyopathy. Previous studies have identified electrocardiographic features that may support a diagnosis of Noonan syndrome. In this two-centre retrospective study, we analysed typical Noonan syndrome-related electrocardiographic features in 30 patients with Noonan syndrome with hypertrophic cardiomyopathy and compared these with the electrocardiographic features in 15 children with sarcomeric hypertrophic cardiomyopathy. Typical Noonan syndrome-related electrocardiographic features are a negative aVF, small left precordial R-waves, large right precordial S-waves, and abnormal Q-wave. We also analysed electrocardiographic features of hypertrophic cardiomyopathy: ST-segment abnormalities and T-wave abnormalities. A negative aVF was seen in 83% of patients with Noonan syndrome-related hypertrophic cardiomyopathy in contrast to 27% of patients with primary sarcomeric hypertrophic cardiomyopathy (p < 0.001). An extreme QRS axis in the north-west was seen only in patients with Noonan syndrome-related hypertrophic cardiomyopathy. This QRS axis deviation is likely to be determined by the Noonan syndrome-related hypertrophic cardiomyopathy and not by the type of hypertrophic cardiomyopathy. There were no differences between the two groups in the frequency of large right precordial S-waves and small R-waves in the left precordial leads V5 and V6. However, an abnormal R/S ratio was more often seen in patients with Noonan syndrome-related hypertrophic cardiomyopathy (p < 0.001). Pathologic Q-waves were seen statistically more frequently in patients with sarcomeric hypertrophic cardiomyopathy (p = 0.009). The occurrence of ST-segment and T-wave pathology did not statistically differ between the two groups. Electrography can be of use in differentiating sarcomeric hypertrophic cardiomyopathy from Noonan syndrome-related hypertrophic cardiomyopathy.

Bleeding phenotype and hemostatic evaluation by thrombin generation in children with Noonan syndrome: A prospective study.

BACKGROUND: This study aimed to evaluate the bleeding phenotype and to conduct a comprehensive hemostatic evaluation in individuals with Noonan syndrome (NS), a dominantly inherited disorder caused by pathogenic variants in genes associated with the Ras/MAPK signaling pathway. METHODS: Children with a genetically confirmed diagnosis of NS underwent clinical evaluation, routine laboratory tests, platelet function testing, and thrombin generation (TG) assessment. RESULTS: The study included 24 children. The most frequently reported bleeding symptoms were easy bruising and epistaxis, while bleeding complications were observed in 15% of surgical procedures. Various hemostatic abnormalities were identified, including platelet dysfunction, von Willebrand disease, and clotting factor deficiencies. Abnormal platelet function was observed in 50% of the patients, and significantly lower TG parameters were found compared to controls. However, no significant correlation was observed between bleeding symptoms and TG results. CONCLUSIONS: The study suggests that the bleeding diathesis in NS is multifactorial, involving both platelet dysfunction and deficiencies of plasma coagulation factors. The potential role of TG assay as an ancillary tool for predicting bleeding tendencies in individuals with NS undergoing surgery warrants further investigation.

Noonan Syndrome-related Myeloproliferative Disorder Occurring in the Neonatal Period: Case Report and Literature Review.

Noonan syndrome-related myeloproliferative disorder (NS/MPD) and juvenile myelomonocytic leukemia (JMML) are rare MPDs that occur in young children. We herein report a case of NS/MPD with neonatal onset. The patient had a characteristic appearance and high monocyte count in the peripheral blood and bone marrow. Genetic testing showed the E139D mutation in PTPN11 ; however, the patient did not meet all the diagnostic criteria for JMML, and we thus diagnosed him with NS/MPD. Eight other cases of NS/MPD with neonatal onset are also summarized. The initial presentation varied, and the prognosis was considered poor compared with previous reports of NS/MPD.

Chylothorax related to acute SARS-CoV-2 infection in a patient with Noonan syndrome with prior uncomplicated cardiac surgeries.

SARS-CoV-2 is a novel coronavirus that has rarely been associated with chylothorax. Patients with Noonan syndrome are at risk for developing chylothorax, especially after cardiothoracic interventions. We present the case of SARS-CoV-2 infection triggering the underlying tendency of a patient with Noonan syndrome to develop chylothorax who did not develop it even after prior cardiothoracic interventions. Patient presented in respiratory distress without hypoxia and was found, on imaging, to have a large right-sided pleural effusion, which was eventually classified as chylothorax. The patient was then started on a low-fat diet. Chest tube drainage substantially reduced the effusion in size, and it remained stable. Our report highlights that SARS-CoV-2 infection can cause the development of a chylothorax or a chylous effusion in patients with Noonan syndrome or among populations with a similar predisposition. A high index of suspicion in vulnerable patients or those not responding to traditional therapy should exist with providers, thus leading to the testing of the fluid to confirm the diagnosis.

Myocardial hypertrophy with aortic dysplasia: a rare case of Noonan syndrome.

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