Complication Of Neurofibromatosis Type Research Articles

Color duplex ultrasonography in detecting renal artery abnormalities in a patient with neurofibromatosis 1: a case report

Neurofibromatosis type 1 (NF1) is a rare disease; it involves not only the nervous system, but also both large and small arteries. Common vascular complications of NF1 include arterial stenosis, aneurysms, and arteriovenous fistulas involving the abdominal aorta and its branches. A coexisting left renal artery stenosis and aneurysm in a pediatric patient with NF1 was initially detected by color duplex ultrasonography in our institute.

Renal vascular disease in neurofibromatosis type 2: association or coincidence?

Neurofibromatosis type 2 (NF2) remains a challenging diagnosis in childhood where there may be no neurological involvement. A 12-month-old male in whom NF2 was suspected because of characteristic ophthalmological and cutaneous lesions is reported. Cranial MRI showed no tumours. A pathogenic mutation was identified on NF2 gene analysis. The child developed hypertension due to renal vascular disease. Although renal vascular disease is a recognized complication of neurofibromatosis type 1 (NF1), it has not been reported in NF2.

Neurofibromatosis: the most frequent hereditary tumor predisposition syndrome

With an incidence of one in 3000 to 4000 individuals, neurofibromatosis type 1 (NF1) is one of the most common autosomal dominant genetic diseases and very likely the most frequent disorder with increased cancer risk. Approximately fifty percent of all patients are familial cases and the remaining half consists of sporadic cases with no affected parent. The hallmark clinical features present in over 90% of all patients are café-au-lait spots and neurofibromas. However, the disorder should not be underestimated as a "mere cosmetic problem", since NF1 patients are at increased risk to also develop malignant tumours, such as malignant peripheral nerve sheath tumours (MPNST), juvenile myelomonocytic leukaemia (JMML), optic glioma and pheochomocytoma. Renovascular disease represents an additional risk factor for NF1 patients. The NF1 gene is a classic example for a tumour suppressor gene. It functions as a negative regulator of the protooncogene Ras. This function explains well its involvement in tumour formation. During the last 15 years, since the cloning of the gene, enormous progress has been made towards a better understanding of the natural history of the disorder. However, it cannot be said if and when a cure of the disorder will be possible. Great advantages have been achieved in the monitoring and management of several NF1 complications, for instance in the treatment of tibia pseudarthrosis and optic gliomas. Owing to the technical improvements of the approaches applied to identify NF1-mutations molecular-genetic testing with high mutation detection rates may help nowadays in patients in which the clinical diagnosis may not readily be established, such as in young children or atypical cases. A greater awareness of the complications and the different expression forms of NF1 and NF2 on the part of all types of physicians will further help to offer all patients adequate and timely counselling and treatment. The establishment of multi-disciplinary counselling and treatment centres for neurofibromatosis could be an important step towards a better management of NF1 and NF2 patients.

Role for the epidermal growth factor receptor in neurofibromatosis-related peripheral nerve tumorigenesis

Benign neurofibromas and malignant peripheral nerve sheath tumors are serious complications of neurofibromatosis type 1. The epidermal growth factor receptor is not expressed by normal Schwann cells, yet is overexpressed in subpopulations of Nf1 mutant Schwann cells. We evaluated the role of EGFR in Schwann cell tumorigenesis. Expression of EGFR in transgenic mouse Schwann cells elicited features of neurofibromas: Schwann cell hyperplasia, excess collagen, mast cell accumulation, and progressive dissociation of non-myelin-forming Schwann cells from axons. Mating EGFR transgenic mice to Nf1 hemizygotes did not enhance this phenotype. Genetic reduction of EGFR in Nf1 +/− ; p53 +/− mice that develop sarcomas significantly improved survival. Thus, gain- and loss-of-function experiments support the relevance of EGFR to peripheral nerve tumor formation.

Abdominal migraine in children with neurofibromatosis type 1: a case series and review of gastrointestinal involvement in NF1.

Symptomatic involvement of the gastrointestinal tract in children with neurofibromatosis type 1 (NF1) is rare. Most reported complications in adults are caused by the presence of neurofibromas in the stomach, small bowel, or mesentery. In contrast, abdominal pain in children with NF1 may be the result of nonanatomic causes, such as migraine. There are no previous reports of an association between abdominal migraine and NF1. Children with abdominal migraine were identified from a group of children with NF1, all of whom had been followed up for a minimum of 3 years. Medical records of cases were reviewed independently by two authors. MEDLINE was searched via PubMed for all reports of children with NF1 and any associated gastrointestinal involvement. Six children with NF1 and intermittent, episodic, severe abdominal pain are reported. Investigations for obstructive or inflammatory causes of abdominal pain were negative. All patients had previously been diagnosed with migraine headaches by a neurologist. In five of the six patients, propranolol (10-15 mg three times daily) resulted in relief of their abdominal pain within days of starting therapy. Our review identified 24 children in the medical literature with gastrointestinal complications of NF1, mostly secondary to visceral neurofibromas. In almost all of these cases, clinical examination and simple radiologic investigations led to the definitive diagnosis. There were no reports of abdominal migraine complicating NF1. Abdominal pain secondary to migraine is an unrecognized cause of abdominal pain in children with NF1 and may be more common than anatomic causes of abdominal pain in children with NF1. In children with NF1 and severe recurrent abdominal pain in whom an evaluation for anatomic lesions is negative, a trial of migraine therapy may be indicated.

Abdominal Migraine in Children With Neurofibromatosis Type 1: A Case Series and Review of Gastrointestinal Involvement in NF1

ABSTRACTBackgroundSymptomatic involvement of the gastrointestinal tract in children with neurofibromatosis type 1 (NF1) is rare. Most reported complications in adults are caused by the presence of neurofibromas in the stomach, small bowel, or mesentery. In contrast, abdominal pain in children with NF1 may be the result of nonanatomic causes, such as migraine. There are no previous reports of an association between abdominal migraine and NF1.MethodsChildren with abdominal migraine were identified from a group of children with NF1, all of whom had been followed up for a minimum of 3 years. Medical records of cases were reviewed independently by two authors. MEDLINE was searched via PubMed for all reports of children with NF1 and any associated gastrointestinal involvement.ResultsSix children with NF1 and intermittent, episodic, severe abdominal pain are reported. Investigations for obstructive or inflammatory causes of abdominal pain were negative. All patients had previously been diagnosed with migraine headaches by a neurologist. In five of the six patients, propranolol (10–15 mg three times daily) resulted in relief of their abdominal pain within days of starting therapy. Our review identified 24 children in the medical literature with gastrointestinal complications of NF1, mostly secondary to visceral neurofibromas. In almost all of these cases, clinical examination and simple radiologic investigations led to the definitive diagnosis. There were no reports of abdominal migraine complicating NF1.ConclusionsAbdominal pain secondary to migraine is an unrecognized cause of abdominal pain in children with NF1 and may be more common than anatomic causes of abdominal pain in children with NF1. In children with NF1 and severe recurrent abdominal pain in whom an evaluation for anatomic lesions is negative, a trial of migraine therapy may be indicated.

Noninvasive Evaluation of Arterial Abnormalities in Young Patients with Neurofibromatosis Type 1

Neurofibromatosis regroups at least two different autosomal dominant genetic disorders: neurofibromatosis type 1 (NF1) and neurofibromatosis type 2 (NF2). Vascular disease is an underestimated complication of NF1. Few studies are available on this, all based on case reports. Neurofibromin, NF1 protein product, has also been detected in aortic smooth muscle. The purpose of this study was to evaluate the physical properties of the vessels, by measuring the carotid-femoral pulse wave velocity (PWV). This parameter was assessed by the Complior, a new noninvasive, validated device, used to screen a large population. The authors studied 64 neurofibromatosis patients (34 boys and 30 girls) with a mean age of 12 years (range 5-25 years). To investigate the presence of vascular lesions, aortic stiffness was evaluated by carotid-femoral PWV by using an automatic processor (Complior). They compared data from the PWV with a control group (30 healthy children, 17 boys and 13 girls, mean age 11 years, range 5-23 years). The calculated mean PWV in the control group was 6.5 +/- 1.15 m/s. The mean PWV of the 64 young patients with NF1 was 6.3 +/- 1.02 m/s. There was no difference between the two groups (p=0.39). Nevertheless, analysis of the linear regression has shown a linear relationship between systolic blood pressure (SBP) and PWV in the control group, while in NF1 patients this relationship is not present. The authors suggest that the coexistence of different factors, such as intimal proliferation, thinning media, fragmentation of the elastic tissue, irregularity, stenosis and tortuosity of the vessels, dysplasia of the small vessels, that counterbalance PWV, normalize the mean value. They emphasize the importance of a careful vascular evaluation, using noninvasive method, such as Complior. This device is well accepted by NF1 patients.

Renovascular disease and hypertension in children with neurofibromatosis.

Neurofibromatosis type 1 (NF1) is associated with vascular lesions, such as renal artery stenosis, and secondary hypertension. The real prevalence is largely unknown, particularly in children. We observed 27 patients with NF1, mean age 12.8 years (range 4.2-24 years), for 2-10 years to assess the association of NF1 with vascular abnormalities and secondary hypertension. Patients were studied with angiography, 24-h blood pressure monitoring, a captopril test, and Doppler ultrasonography of aorta and renal arteries. The prevalence of hypertension was 18.5%; 61.5% of patients studied with angiography had vascular lesions, half of whom were apparently normotensive. However, they had abnormal 24-h blood pressure monitoring, which was a first sign of poor blood pressure control. Those patients with severe hypertension (11.1%) were successfully treated with percutaneous transluminal angioplasty (PTA); stenosis recurred in 2 of 3 patients after a 2-year follow-up period, and was responsive to drugs. We conclude that hypertension is a frequent complication of NF1 in pediatric patients, it is usually secondary to typical vascular lesions, and requires careful follow-up. Ambulatory blood pressure monitoring (24-h) is a sensitive method for detecting initial alterations of the blood pressure pattern. PTA may be an effective treatment in this condition.

Hyperactive Ras as a therapeutic target in neurofibromatosis type 1

The NF1 gene encodes neurofibromin, a GTPase-activating protein (GAP) for members of the p21(ras) (Ras) family, which negatively regulates Ras output by accelerating the conversion of active Ras. GTP to inactive Ras.GDP. Analysis of tumors from patients with neurofibromatosis type 1 (NF1) has shown biochemical evidence of hyperactive Ras as well as frequent loss of the normal NF1 allele, consistent with its role as a tumor suppressor gene. Taken together, these data suggest that novel therapeutics directed against components of the Ras signaling cascade might provide effective treatments for certain pathological complications of NF1. Here we summarize data that support a role for hyperactive Ras in NF1 disease, including Ras processing, activation, and down-regulation. We review targets for rational drug design, provide preliminary results, and discuss implications for future studies. Am. J. Med. Genet. (Semin. Med. Genet.) 89:14-22, 1999.

Malignant and benign tumors in patients with neurofibromatosis type 1 in a defined Swedish population

BACKGROUND The development of malignant and benign tumors in patients with neurofibromatosis type 1 (NF1) was investigated in a long term follow-up study of 70 adult NF1 patients living in Göteborg, Sweden, on January 1, 1978. Their mean age at that time was 44 years (range, 20-81 years). The 70 NF1 patients had previously been investigated in a population-based study. METHODS The first part of this study involved a cancer registry study. The authors compared the number of tumors in the 70 NF1 patients reported to the Swedish Cancer Registry during the period 1978-1989 with the number of tumors expected in the general population by matching the incidence rates of the two populations specific to age, time of follow-up, and gender. The 95% confidence interval for the risk quotient between the risk to the patients and the risk to the general population was estimated. The second part of the study was a clinical pathologic follow-up study. All living patients were offered a clinical reexamination in 1990. All hospital records for all the NF1 patients were reviewed, and death certificates were also reviewed when available. RESULTS Malignant tumors were reported to the Cancer Registry four times as often in the NF1 patient group as in the general population (95% confidence interval, 2.1-7.6) during the follow-up period 1978-1989. Before 1978, 5 of 70 patients (7%) had 6 malignant tumors; these patients were not included in the Cancer Registry study. Using all available clinical data on the 70 NF1 patients from their birth up to 1990, the authors found that 17 of 70 patients (24%) had developed a total of 19 malignant tumors, namely, 5 sarcomas (in 7% of patients), 13 carcinomas (in 16%), and 1 malignant melanoma (in 1%). Four pheochromocytomas (in 6% of patients), 2 adenomas, and 1 C-cell hyperplasia were diagnosed. Five gastrointestinal stromal tumors (in 7% of patients) were also diagnosed. CONCLUSIONS Malignant tumors were reported to the Swedish Cancer Registry significantly more often in the NF1 patients than was expected in the general population matched for age, gender, and time of follow-up. The development of tumors is part of the NF1 disease process, and this deserves attention both in the clinical setting and in family counseling dealing with complications of NF1 in adulthood. Cancer 1997; 79:2125-31. © 1997 American Cancer Society.

Malignant and benign tumors in patients with neurofibromatosis type 1 in a defined Swedish population

The development of malignant and benign tumors in patient with neurofibromatosis type 1 (NF1) was investigated in a long term follow-up study of 70 adult NF1 patients living in Göteborg, Sweden, on January 1, 1978. Their mean age at that time was 44 years (range, 20-81 years). The 70 NF1 patients had previously been investigated in a population-based study. The first part of this study involved a cancer registry study. The authors compared the number of tumors in the 70 NF1 patients reported to the Swedish Cancer Registry during the period 1978-1989 with the number of tumors expected in the general population by matching the incidence rates of the two populations specific to age, time of follow-up, and gender. The 95% confidence interval for the risk quotient between the risk to the patients and the risk to the general population was estimated. The second part of the study was a clinical pathologic follow-up study. All living patients were offered a clinical reexamination in 1990. All hospital records for all the NF1 patients were reviewed, and death certificates were also reviewed when available. Malignant tumors were reported to the Cancer Registry four times as often in the NF1 patient group as in the general population (95% confidence interval, 2.1-7.6) during the follow-up period 1978-1989. Before 1978, 5 of 70 patients (7%) had 6 malignant tumors; these patients were not included in the Cancer Registry study. Using all available clinical data on the 70 NF1 patients from their birth up to 1990, the authors found that 17 of 70 patients (24%) had developed a total of 19 malignant tumors, namely, 5 sarcomas (in 7% of patients), 13 carcinomas (in 16%), and 1 malignant melanoma (in 1%). Four pheochromocytomas (in 6% of patients), 2 adenomas, and 1 C-cell hyperplasia were diagnosed. Five gastrointestinal stromal tumors (in 7% of patients) were also diagnosed. Malignant tumors were reported to the Swedish Cancer Registry significantly more often in the NF1 patients than was expected in the general population matched for age, gender, and time of follow-up. The development of tumors is part of the NF1 disease process, and this deserves attention both in the clinical setting and in family counseling dealing with complications of NF1 in adulthood.

Neurofibromatosis type 1 and pregnancy.

Neurofibromatosis Type 1 (NF-1) is an autosomal dominant condition which has markedly variable clinical expression, with manifestations ranging from mild cutaneous lesions to severe orthopedic complications and functional impairment. The current obstetrical literature indicates that women with NF-1 have increased complications associated with pregnancy. However, the majority of publications are case reports involving no more than 11 patients each, and are likely biased toward reporting on cases in which complications occurred. This study presents data on pregnancy outcome in 105 women with NF-1. The data were obtained from questionnaires completed by the study participants, and by review of their pregnancy and peripartum medical records. The 105 women had a total of 247 pregnancies, resulting in 182 live births, 44 first trimester spontaneous abortions, 21 elective terminations, and 2 ectopic pregnancies. There were two sets of twins. The cesarean section rate in our series (36%) was greater than the general population rate (9.1-23.5%). In 7 of these patients, the cesarean section was required because of maternal NF-1 complications. The study did not show the previously reported increased incidence of preeclampsia, preterm delivery, intrauterine growth restriction, pregnancy-induced hypertension, stillbirth, spontaneous abortion, or perinatal mortality. Sixty-four (60%) of the one hundred five women reported growth of new neurofibromas during pregnancy and fifty-five (52%) noted enlargement of existing neurofibromas. Nineteen women observed no changes in the size of their neurofibromas and no growth of new neurofibromas during pregnancy.