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PubMedDate not supplied

A diffuse form of neurofibroma of bladder in a child with von Recklinghausen disease.

Neurofibromatosis in infants is uncommon and involvement of the bladder is rare. The reported bladder lesions are rare, and in such patients include neurofibromas, neurofibrosarcomas and rhabdomyosarcomas. Neurofibromas can be of different histologic types. The histologic type of the about 20 reported bladder neurofibromas in children is not clarified or is stated to be of plexiform type. We describe herein an unusual case of a neurofibroma of bladder in a child with von Recklinghausen disease. The therapeutic management and the possible prognostic implication of the type of the bladder neurofibroma and bladder lesions other than neurofibroma are discussed.

Cystectomy↗
PubMed2001

Neurofibroma of the larynx in neurofibromatosis: preoperative computed tomography and magnetic resonance imaging.

Neurofibromas of the larynx are extremely rare. They occur in association with neurofibromatosis less frequently than solitary neurofibromas. However, most laryngeal tumors in neurofibromatosis are neurofibromas. This disorder has 2 histological subtypes, which require different surgical approaches because of their biological differences. Few cross-sectional imaging studies have been performed in neurofibroma of the larynx. We describe a 44-year-old man with neurofibromatosis and nonplexiform neurofibroma of the larynx and discuss the role of preoperative computed tomography and magnetic resonance imaging in this case. The tumor was removed completely using an endolaryngeal approach without an external incision. It was possible to distinguish subtypes preoperatively on cross-sectional imaging. Magnetic resonance imaging provided more sensitive information in the diagnosis of this tumor than computed tomography. Preoperative cross-sectional imaging should be performed to help the surgeon diagnose and choose an appropriate surgical approach for this disorder.

Adult↗
PubMed1999

Plexiform neurofibromas.

Plexiform neurofibromas are among the most common and debilitating complications of neurofibromatosis type 1 (NF1). They account for substantial morbidity, including disfigurement, functional impairment, and may even be life threatening. Plexiform neurofibromas are also subject to transformation into malignant peripheral nerve sheath tumor (MPNST), a complication that is refractory to treatment both because of a paucity of effective therapies for malignant soft tissue sarcomas in general, and because of the delay in diagnosis that results from change of a small portion of a large pre-existing tumor. The current mainstay of treatment of plexiform neurofibromas, and of MPNST for that matter, is surgical resection. The major variables are the timing and means of identification of plexiform neurofibromas, methods of follow-up, and indications for surgery. There is no established means of medical treatment, but research into the molecular pathogenesis of NF1, as well as advances in tumor therapy in general, are opening the way towards clinical trials for plexiform neurofibroma. Am. J. Med. Genet. (Semin. Med. Genet.) 89:31-37, 1999.

Humans↗
PubMed1988

Malignant lymphoma arising in a large congenital neurofibroma of the head and neck. Report of a case.

A lymphoma developed in a large neurofibroma in a young woman who had no other stigmata of neurofibromatosis. The neurofibroma was congenital and extensively involved the soft tissue and bone of the face and neck. Despite multiple attempts to excise the neurofibroma, it persistently recurred. At the age of 30 the patient underwent another resection of the lesion, and a follicular, mixed, small and large cell lymphoma was present within the neurofibroma. Over 3 years the lymphoma transformed into a diffuse large cell type despite the fact that it remained localized to the neurofibroma. After the lymphoma had transformed, the patient received multiagent chemotherapy. She responded well, and a repeat biopsy showed no residual lymphoma. She is alive and well 25 months after completion of chemotherapy. To the best of our knowledge, this is the first report of a lymphoma arising in a soft tissue neoplasm.

Adolescent↗
PubMed2000

Solitary neurofibroma of the anal canal: report of two cases.

Neurofibromas are benign nerve sheath tumors commonly found in patients afflicted with neurofibromatosis-1. In the absence of multiple neurofibromas or a diagnosis of neurofibromatosis-1, neurofibromas are referred to as solitary and have been reported to involve the skin, subcutaneous tissue, deep soft tissue, and viscera of almost all areas of the body. A neurofibroma involving the anal canal is a rare entity, with only one report in the literature. We present two cases in which large masses involving the anal canal of elderly females were locally resected and proved to be neurofibromas by histopathology. Although rare, these tumors should be considered in the differential diagnosis of patients presenting with an anal mass, because resection alone is the treatment of choice.

Aged↗
PubMed2005

Unexpected diagnosis of superficial neurofibroma in a lesion with imaging features of a vascular malformation.

Plexiform neurofibroma is a pathognomonic, often disabling feature of neurofibromatosis type I. Although the target-like appearance of deep plexiform neurofibroma on T2-weighted MRI has been well-described, a second superficial form of plexiform neurofibroma has differing imaging features. We report a 15-year-old boy who presented with multiple cutaneous lesions exhibiting clinical and imaging characteristics of a venolymphatic malformation. These lesions were histologically proved to represent superficial plexiform neurofibromas. We wish to emphasize the unique MR findings of superficial plexiform neurofibromas; these findings are different from the imaging characteristics of the deep form and can be confused with a low-flow vascular malformation.

Adolescent↗
PubMed1981

Genitourinary neurofibromas: clinical significance.

We describe 2 unusual cases of genitourinary neurofibromas. In 1 case a large solitary neurofibroma developed on the glans penis and in the other case a plexiform neurofibroma of the pelvis was present in young women with von Recklinghausen's disease. Each case represents either end of the spectrum of urologic involvement by this rare tumor. The solitary neurofibroma requires only local excision but the plexiform neurofibroma, causing urinary obstruction, necessitates urinary diversion. Recurrence and malignant degeneration, while virtually unheard of in the former, are relatively common in the latter. The prognosis of each type is discussed.

Adolescent↗
PubMed1994

Cervical neurofibroma in a patient with von Recklinghausen's disease.

A case of a huge cervical neurofibroma associated with von Recklinghausen's disease is reported. The patient with von Recklinghausen's disease was a 48-year-old woman complaining of a rapidly growing mass around the neck for the last 6 months. In von Recklinghausen's disease, which corresponds to neurofibromatosis-I, gigantic tumors around the neck often occur. The present case was classified as a plexiform neurofibroma which is derived from the peripheral nervous system, and this type frequently shows malignant change in contrast to other types of neurofibroma. In general, it is difficult to determine the origin of the nerve in cervical neurofibromas. A total extirpation of the tumor was done in our case, and revealed the nerve of origin to be the vagal nerve. Pathologically, H-E stained specimens showed that the tumor was a benign neurofibroma. However, immunostaining of the majority of the tumor cells were positive for PCNA. These results suggest that the tumor of our case possessed a low malignant potential. To date, neither local recurrence nor distant metastasis has been found on subsequent examinations.

Cranial Nerve Neoplasms↗
PubMed2002

Neurofibroma and schwannoma.

PURPOSE OF REVIEW: Neurofibromas and schwannomas are benign peripheral nerve sheath tumours that occur as isolated sporadic lesions, but have their major clinical impact on the neurocutaneous diseases neurofibromatosis 1 and neurofibromatosis 2. The gene products neurofibromin and merlin (schwannomin), respectively, are thought to act as tumour suppressors. The aim of this review is to document recent advances in our understanding of the clinical characteristics and pathogenesis of neurofibromas and schwannomas in the neurofibromatoses. RECENT FINDINGS: Animal models have shed light on the pathogenesis of neurofibromas confirming that the Schwann cell initiates neurofibroma formation. New data suggest that individuals with neurofibromatosis 1 have a 10% lifetime risk of developing malignant peripheral nerve sheath tumours. Positron emission tomography with the glucose analogue 18-fluorodeoxyglucose might be helpful in the diagnosis of malignant peripheral nerve sheath tumours. Such tumours associated with neurofibromatosis 1 show a loss of neurofibromatosis 1 expression and high levels of Ras, but malignant transformation requires additional genetic events that inactivate key cell cycle regulators. Neurofibromatosis 2-associated vestibular schwannomas have variable growth rates that tend to decline with age. Early microsurgery for small tumours results in optimal preservation of hearing and facial nerve function. Currently, radiosurgery for these lesions produces similar results. Systematic follow-up of both groups will determine the best treatment method. Merlin's function as a tumour suppressor has not been elucidated. The control of cell cycle progression and abnormal intracellular and extracellular signalling could all play a part. SUMMARY: Molecular advances will allow a biological approach to targeted therapies for neurofibromas, malignant peripheral nerve sheath tumours and schwannomas. Knowledge of the pathogenesis of these tumours will have implications for our understanding of the neurofibromatoses and of the formation of sporadic tumours.

Animals↗
PubMed1996

Repression of the NF1 gene by Tax may expain the development of neurofibromas in human T-lymphotropic virus type 1 transgenic mice.

In familial neurofibromatosis type 1 (NF1), individuals with a germ line-transmitted NF1 mutation develop multiple neurofibromas. To explain the observation that transgenic mice expressing the human T-lymphotropic virus type 1 (HTLV-1) tax gene under the control of the viral regulatory element also develop multiple neurofibromas, we demonstrate that the Tax trans-regulator can functionally repress NF1 gene expression through a cis-acting element located immediately upstream of its transcriptional start site, thereby allowing the development of benign neurofibromas without the need for direct mutations in NF1. We propose that such a mechanism would suffice to epigenetically alter NF1 gene expression. The fact that transgenic animals have localized rather than diffuse neurofibroma formation, however, suggests that additional genetic or epigenetic events may be required for neurofibroma formation.

3T3 Cells↗
PubMed2007

NF1 plexiform neurofibroma growth rate by volumetric MRI: relationship to age and body weight.

OBJECTIVE: To longitudinally analyze changes in plexiform neurofibroma (PN) volume in relation to age and body growth in children and young adults with neurofibromatosis type 1 and inoperable, symptomatic, or progressive PNs, using a sensitive, automated method of volumetric MRI analysis. METHODS: We included patients 25 years of age and younger with PNs entered in a natural history study or in treatment trials who had volumetric MRI over > or =16 months. RESULTS: We studied 49 patients (median age 8.3 years) with 61 PNs and a median evaluation period of 34 months (range 18 to 70). The PN growth rates varied among patients, but were constant within patients. Thirty-four patients (69%) experienced > or =20% increase in PN volume during the observation period. PN volume increased more rapidly than body weight over time (p = 0.026). Younger patients had the most rapid PN growth rate. CONCLUSIONS: Volume increase of plexiform neurofibromas is a realistic and meaningful trial endpoint. In most patients plexiform neurofibroma growth rate exceeded body growth rate. The youngest patients had the fastest plexiform neurofibroma growth rate, and clinical drug development should be directed toward this population. Age stratification for clinical trials for plexiform neurofibromas should be considered.

Aging↗
PubMed2006

Palatal neurofibroma associated with localized periodontitis.

BACKGROUND: Neurofibromatosis type 1 (NF1) is the most common form of neurofibromatosis. While typically considered a dermatologic disorder, intraoral signs of neurofibromatosis occur quite commonly. This clinical entity can be confused with periodontitis because of the presence of periodontal pockets. In this report, we present the case of a palatal neurofibroma with radiographic involvement in a patient with NF1. METHODS: A 40-year-old female patient was referred from her general dentist to evaluate advanced periodontitis in the maxillary left quadrant. The patient's medical history was significant for a soft tissue lesion excised from her back 11 years previously and diagnosed as a neurofibroma. Subsequent medical examination at that time confirmed a systemic diagnosis of NF1. A comprehensive periodontal evaluation was performed, and panoramic and periapical radiographs were taken. Teeth were tested for vitality. An incisional biopsy was completed for histopathologic examination. RESULTS: The periodontal evaluation revealed the presence of 6 to 9 mm probing depths adjacent to teeth #14 and #15. Panoramic and periapical radiographs showed a circumscribed 0.8x0.9-cm unilocular radiolucency superimposed over the root of tooth #13 and extensive horizontal bone loss on the distal side of #15. Incisional biopsy confirmed the presence of a neurofibroma, and because of the extent of the lesion, the patient was referred to the Oral and Maxillofacial Surgery service for complete excision. CONCLUSIONS: Neurofibromas can cause extensive destruction of alveolar bone, mimicking periodontitis. Due to the potential systemic and genetic implications, the diagnosis of neurofibroma requires appropriate medical referral.

Adult↗
PubMed2006

[Bladder neurofibroma: case report and bibliographic review].

OBJECTIVE: The prevalence of the disease is 1/3000 newborns; it is more frequent in men than in women with a 3:1 ratio in all races. Genitourinary tract neurofibromas usually arise from the pelvic and bladder nerves, and the prostatic plexus. Bladder is the most frequently affected organ of the urinary tract; bladder neurofibromatosis may present as a diffuse infiltrative process or an isolated neurofibroma. Bladder neurofibromas arise from nervous ganglia of the bladder wall and stain positive for protein S-100 and type IV collagen with immunohistochemical techniques. METHODS: We performed a bibliographic review about urinary tract neurofibromas, and specifically of bladder neurofibroma. We report the case of a 45-year-old female consulting for voiding symptoms and recurrent urinary tract infections. Imaging tests showed a mass in the left lateral wall of the bladder and diffuse thickening of the bladder wall. The thickening of the bladder wall is the most characteristic finding in imaging tests, which may also be present in other diseases such as inflammatory pseudotumor and leiomyoma, so that final diagnosis should be achieved by pathologic study. RESULTS: The case is relevant for the absence of previous diagnosis of neurofibromatosis, being bladder involvement its clinical debut. This is why it was difficult to suspect the final diagnosis: the absence of other characteristic clinical manifestations of the disease. Transurethral resection of the tumor was performed and pathologic and immunohistochemical studies offered the final diagnosis. The patient was followed in the urology clinic and also sent to the internal medicine department to rule out other organs involvement of the disease. CONCLUSIONS: Neurofibromatosis is a rare systemic disease, and urinary tract involvement is rarer. Bladder is the most frequently involved organ in the urinary tract, generally as a diffuse infiltration or more rarely a solitary tumor. The final diagnosis is pathological and immunohistochemical. Treatment is usually conservative. The patient should be worked up to rule out other manifestations of the disease, and followed to evaluate the development of new lesions.

Female↗
PubMed2000

Clinic-based study of plexiform neurofibromas in neurofibromatosis 1.

Individuals with neurofibromatosis 1 (NF1) develop both benign and malignant tumors at an increased frequency. One of the most common benign tumors in NF1 is the plexiform neurofibroma. These tumors cause significant morbidity and mortality on account of their propensity to grow and affect adjacent normal tissues. To determine the clinical profile of plexiform neurofibromas in NF1, we conducted a retrospective review of 68 NF1 patients with plexiform neurofibroma. In our series, 44% of tumors were detected by 5 years of age and most were located in the trunk and extremities. Only two patients developed malignant peripheral nerve sheath tumors in their preexisting plexiform neurofibromas. Lastly, we demonstrate that there were no specific clinical features of NF1 associated with the presence of plexiform neurofibroma. These results underscore the importance of careful serial examinations in the evaluation of patients with NF1.

Adolescent↗
PubMedDate not supplied

Is the distribution of dermal neurofibromas in neurofibromatosis type 1 (NF1) related to the pattern of the skin surface temperature?

The formation of dermal neurofibromas is a hallmark of the neurofibromatosis type 1 (NF1). A total loss of the NF1 gene product by stochastic events inactivating the wild type allele in Schwann cells should precede the development of neurofibromas. Dermal neurofibromas tend to be located mainly on the surface of the trunk and not in the body periphery. This distribution partly resembles the density of sensitive nerve endings in the epidermis. Our hypothesis is that a better correlation concerns the pattern of normal body surface temperature. According to our clinical observations we assume that in skin areas with higher temperatures the number of visible dermal neurofibromas is higher than in colder areas such as the arms/legs or nose. It is known that differences in temperature are able to determine differentiation. We suggest that the regulation of skin temperature is also involved in the formation of NF1 dermal neurofibromas and is related to the intrafamilial variability in NF1.

Adolescent↗
PubMed1991

The ultrastructure of schwannoma and neurofibroma of the peripheral nerves.

An electron microscopic study of 4 solitary schwannomas and 2 neurofibromas of peripheral nerves was performed with the aim of investigating the debated histogenesis of the two types of lesion. Our observations confirm that solitary schwannoma is composed almost exclusively of cells with characteristics of differentiated Schwann cells, thus providing evidence for a neuroectodermal origin of the tumor. Analysis of the ultrastructure of neurofibroma shows the presence of 3 different types of cells: Schwann-like cells, perineurial-like cells, and fibroblast-like cells. Perineurial-like cells were prevalent in our observations. These findings as well as the many controversial aspects of the origin of neurofibroma could be explained by separating this type of neoplasia into two pathological forms: perineurial and interstitial. Moreover, the numerous differences between solitary schwannoma and neurofibroma allow us to hypothesize a different cellular origin for each tumor. If confirmed by further observations, this would explain the difference in the capacity of the two types of neoplasia to undergo malignant change, an occurrence almost unknown in solitary schwannoma yet relatively common in neurofibroma.

Collagen↗
PubMed1991

Presence of type I and VI collagen mRNAs in endothelial cells in cutaneous neurofibromas.

In situ hybridization and peroxidase anti-peroxidase immunodetection were used in the same tissue sections to elucidate the spatial distribution of collagen gene expression in cutaneous neurofibromas, particularly in relation to blood vessels; the latter structures were identified by the presence of factor VIII-related antigen. The data indicate a clear relationship between the vascular structures and sites of locally elevated expression of type I and VI collagen genes. Specifically, some, but not all, blood vessels were surrounded by stromal cells highly active in expressing pro alpha 1(I) and alpha 2(VI) collagen genes. Furthermore, these genes were expressed by a subpopulation of endothelial cells within the walls of blood vessels traversing the lesion. To quantitate the overall expression of five genetically distinct collagen genes in cutaneous neurofibromas, we performed Northern analyses and slot blot hybridizations with pro alpha 1 (I), pro alpha 2 (I), pro alpha 1 (III), pro alpha 1 (IV) and alpha 2(VI) collagen cDNAs. Although the mRNA levels for all five genes were slightly increased in neurofibroma tissue, only the abundance of alpha 2(VI) collagen mRNAs was significantly elevated, as compared with normal skin. We conclude that endothelial cell populations with different levels of collagen gene expression exist within cutaneous neurofibromas: some are actively expressing type I and VI collagen genes, whereas in other the expression of these genes is effectively down-regulated. The markedly elevated steady-state levels of type VI collagen mRNAs suggest that synthesis of type VI collagen may contribute to the growth and architecture of cutaneous neurofibromas.

Collagen↗
PubMed1986

Expression of melanoma-associated antigens by normal and neurofibroma Schwann cells.

The cell surface antigen distribution on traumatic neuroma Schwann cells and neurofibroma Schwann-like cells was characterized using monoclonal antibodies that define melanoma-associated antigens. Immunofluorescence staining of cultured cells, immunoprecipitation of radioiodinated antigens from cells placed in short-term cultures, and immunoperoxidase staining of frozen tissue sections revealed most of the melanoma-associated antigens tested on traumatic neuroma and neurofibroma Schwann cells and on fetal and adult femoral nerve. The cross-reactivity of the antibodies with neural cells may reflect the common neural crest embryological origin of Schwann cells and melanocytes. Cell sorter analysis of neurofibroma cells using a monoclonal antibody directed against the melanoma nerve growth factor receptor resulted in cell cultures highly enriched for Schwann-like cells which may bear the genetic defect responsible for neurofibromatosis. The antigen detected by this monoclonal antibody is the neurofibroma nerve growth factor receptor and the antibody was a potent inhibitor of nerve growth factor binding to neurofibroma cells.

Antibodies, Monoclonal↗