Abdominal tumors in patients with neurofibromatosis type I: Genotype-phenotype relationships

BackgroundGastrointestinal stromal tumors have been detected in 25% of the necropsies performed on NF1 patients, but have been reported only in 7% of NF1 patients in the largest series. Such data imply an important gap between the true presence of tumors and those diagnosed. Few genotype-phenotype relationships have been described but to date none referring to abdominal tumors.ObjectivesEvaluate retrospectively the efficacy of a regular and proactive follow-up of NF1 patients to early diagnose abdominal tumors and report their mutations.MethodsCohort study performed between 2010 and 2020, with 43 NF1 adult patients followed at our Dermatology department.ResultsEight abdominal tumors were diagnosed in six patients, meaning that 14% of the followed patients developed an abdominal tumor. Five patients (83%) were asymptomatic. Five (83.3%) had a family history of NF1 with abdominal tumors (patients 1,2 and 3,4,5 were relatives).ConclusionsAlthough currently gastrointestinal routine screening investigations for asymptomatic patients are not recommended in the guidelines, the family aggregation in our series suggests it should be considered a close follow-up of the relatives of a patient with an NF1-related abdominal tumor. Also, for the first time, two mutations [c.2041C > T (p.Arg681Ter) and c.4537C > T (p.Arg1513*)] have been associated with family aggregation of abdominal tumors in NF1 patients.     

Brain gliomas,hydrocephalus and idiopathic aqueduct stenosis in children with neurofibromatosis type 1

PurposeTo evaluate the incidence and clinical importance of brain gliomas – optic pathway gliomas (OPGs) and especially gliomas outside the optic pathway (GOOP) for children with neurofibromatosis type 1 (NF1), additionally, to assess the causes of obstructive hydrocephalus in NF1 children with an emphasis on cases caused by idiopathic aqueduct stenosis.Subjects and methodsWe analysed data from 285 NF1 children followed up on our department from 1990 to 2010 by the same examination battery.ResultsWe have found OPGs in 77/285 (27%) children and GOOPs in 29/285 (10,2%) of NF1 children, of who 19 had OPG and GOOP together, so the total number of brain glioma was 87/285 (30,5%). GOOPs were significantly more often treated than OPGs (p > 0.01). OPGs contain clinically important subgroup of 14/285 (4.9%) spreading to hypothalamus. Spontaneous regression was documented in 4/285 (1.4%) gliomas and the same number of NF1 children died due to gliomas.Obstructive hydrocephalus was found in 22/285 (7.7%) patients and 14/22 cases were due to glioma. Idiopathic aqueduct stenosis caused hydrocephalus in 6/22 cases and was found in 2.1% of NF1 children. Two had other cause.ConclusionsThe total brain glioma number (OPGs and only GOOPs together) better reflected the overall brain tumour risk for NF1 children. However, GOOPs occur less frequently than OPGs, they are more clinically relevant. The obstructive hydrocephalus was severe and featuring frequent complication, especially those with GOOP. Idiopathic aqueduct stenosis shows an unpredictable cause of hydrocephalus in comparison with glioma and is another reason for careful neurologic follow up.     

Neurofibromatosis type 2 in Phelan-McDermid syndrome: Institutional experience and review of the literature

Phelan-McDermid syndrome (PMS) is a rare neurodevelopmental disorder caused by rearrangements on chromosome 22q13.3 or sequence variants in SHANK3. Individuals with PMS caused by a 22q terminal deletion and a ring chromosome are at increased risk for Neurofibromatosis type 2 (NF2). However, the prevalence of NF2 in individuals with PMS and a r (22) is unknown.Individuals with PMS and a r (22) chromosome evaluated at the Greenwood Genetic Center (GGC) or by international collaborators, or identified through the PMS International Registry (PMSIR) were contacted and participated in a clinical questionnaire. Forty-four families completed the questionnaire and consented for the study. Of the individuals with a r (22), 7 (16%) carried a diagnosis of NF2. The average age of diagnosis of r (22) was 18 years old in individuals with NF2 and three years old in individuals without NF2 (p-value <0.001). Clinical findings were similar among all individuals in our sample with the exception of hearing loss, present in 57% of individuals with NF2 and 8% of individuals without NF2 (p-value <0.01).This is the largest clinical report of individuals with PMS and a r (22) chromosome. We show a diagnosis of NF2 in individuals with r (22) is not uncommon and may be under ascertained. Moreover, the presentation of NF2 in this cohort is variable and lifelong routine screening for features of NF2 in this population should be considered.     

Dermoscopy of the iris: identification of Lisch nodules and contribution to the diagnosis of neurofibromatosis type 1

Neurofibromatosis is a common genodermatosis, whose diagnosis often involves the participation of a dermatologist. A case of a 38-year-old female patient with four café-au-lait macules and eleven neurofibromas on clinical examination is presented. Dermoscopy allowed the identification of Lisch nodules in the iris, bilaterally. The combination of these findings allowed the diagnosis of neurofibromatosis type 1, according to NIH criteria. Lisch nodules are melanocytic hamartomas of the iris, which must be evaluated through a visual augmentation method, usually employed in ophthalmology. Alternatively, dermoscopy can be used and contribute to the early diagnosis of neurofibromatosis type 1.     

Sudden death due to rupture of the right internal carotid artery in neurofibromatosis type 1: A case report

Vascular involvement is a well-recognized manifestation of neurofibromatosis type 1 (NF1) which has the potential to be fatal when disrupted. We here present a case of sudden death due to the fatal arterial rupture resulted from infiltration of the neurofibromas. A 42-year-old man who suffered from NF1 presented a 1-h history of sudden onset of pain in his right cervical region. His condition worsened and became unconscious on his way to the emergency room. Despite resuscitation efforts, he died 30 min later without regaining consciousness. Autopsy examination showed that a neurofibroma located around the right internal carotid artery, confirmed immunohistochemically with S-100, vimentin and CD34. Furthermore, proliferation of spindle cells positive for S-100 was seen in the wall of right internal carotid artery, which was disrupted and resulted in a hemorrhage. These findings suggest that the artery was disrupted by neurofibromas in the vascular wall, which led to fragility of the vessel. On the basis of these findings, we concluded that the cause of death was asphyxia resulting from airway obstruction compressed by the hematoma due to the arterial rupture. As the locality of the neurofibroma and hemorrhage were closed to the carotid baroreflex, we considered another possible mechanism of his sudden death, which could be cardiac inhibition induced by vagal stimulation. We hope this case will increase recognition of NF-1 vasculopathy when encountering any sudden death in NF1 patients.     

Developmental dosing with a MEK inhibitor (PD0325901) rescues myopathic features of the muscle-specific but not limb-specific Nf1 knockout mouse

Neurofibromatosis Type 1 (NF1) is a common autosomal dominant genetic disorder While NF1 is primarily associated with predisposition for tumor formation, muscle weakness has emerged as having a significant impact on quality of life. NF1 inactivation is linked with a canonical upregulation Ras-MEK-ERK signaling. This in this study we tested the capacity of the small molecule MEK inhibitor PD0325901 to influence the intramyocellular lipid accumulation associated with NF1 deficiency. Established murine models of tissue specific Nf1 deletion in skeletal muscle (Nf1_MyoD^?/?) and limb mesenchyme (Nf1_Prx1^?/?) were tested.Developmental PD0325901 dosing of dams pregnant with Nf1_MyoD^?/? progeny rescued the phenotype of day 3 pups including body weight and lipid accumulation by Oil Red O staining. In contrast, PD0325901 treatment of 4?week old Nf1_Prx1^?/? mice for 8?weeks had no impact on body weight, muscle wet weight, activity, or intramyocellular lipid. Examination of day 3 Nf1_Prx1^?/? pups showed differences between the two tissue-specific knockout strains, with lipid staining greatest in Nf1_MyoD^?/? mice, and fibrosis higher in Nf1_Prx1^?/? mice.These data show that a MEK/ERK dependent mechanism underlies NF1 muscle metabolism during development. However, crosstalk from Nf1-deficient non-muscle mesenchymal cells may impact upon muscle metabolism and fibrosis in neonatal and mature myofibers.