Unexpected high frequency of neurofibroma in the celiac ganglion of German cattle.

In a study originally designed to find potential risk factors for bovine spongiform encephalopathy (BSE) we examined tissues from 403 Holstein Frisian cattle in total. These included 20 BSE cattle and their 236 birth- and feeding cohort animals plus 32 offspring, 103 age, breed and district-matched control cattle and further twelve cattle with neurological signs. In addition to the obex, we examined the celiac ganglion, cervical cranial ganglion, trigeminal ganglion and proximal ganglion of the vagus nerve using histological techniques. Unexpectedly, we found a high number of neurofibroma, a benign peripheral nerve sheath tumor consisting of Schwann cells, fibroblasts and perineural cells. The neurofibroma were present only in the celiac ganglion and found during histologic examination. With a frequency of 9.91% in BSE cattle and their cohorts (case animals) and 9.09% in the age, breed and district matched control animals there seems to be no correlation between the occurrence of BSE and neurofibroma. Benign peripheral nerve sheath tumors have been described more often in cattle than in other domestic animals. Usually, they are incidental macroscopic findings in the thoracic ganglia during meat inspection. To our knowledge, there are no previous systematic histologic studies including bovine celiac ganglia at all. The high incidence of celiac ganglia neurofibroma may play a role in the frequently occurring abomasal displacements in Holstein Frisian cattle as the tumors might cause a gastrointestinal motility disorder. At present a genetic predisposition for these neoplasms cannot be ruled out.

What's new in nerve sheath tumors.

Peripheral nerve sheath tumors are commonly encountered and frequently pose challenges to the pathologist and the clinician. This review discusses the wide range of entities with an emphasis on new discoveries in the past decade. Clinical, histologic, immunohistochemical, and pathogenetic findings are discussed with an emphasis on clinical implications and differential diagnosis.

Topical sirolimus as an effective treatment for a deep neurofibroma in a patient with neurofibromatosis type I.

A 14-year-old boy with neurofibromatosis type I (NF1) presented with a painful neurofibroma on his right palm. The lesion was treated with topical sirolimus, resulting in decreased size and pain and improvement in motor function of his hand. This case demonstrates the efficacy of topical sirolimus in the management of neurofibromas in NF1.

Cellular Origin, Tumor Progression, and Pathogenic Mechanisms of Cutaneous Neurofibromas Revealed by Mice with Nf1 Knockout in Boundary Cap Cells.

Patients carrying an inactive NF1 allele develop tumors of Schwann cell origin called neurofibromas (NF). Genetically engineered mouse models have significantly enriched our understanding of plexiform forms of NFs (pNF). However, this has not been the case for cutaneous neurofibromas (cNF), observed in all NF1 patients, as no previous model recapitulates their development. Here, we show that conditional Nf1 inactivation in Prss56-positive boundary cap cells leads to bona fide pNFs and cNFs. This work identifies subepidermal glia as a likely candidate for the cellular origin of cNFs and provides insights on disease mechanisms, revealing a long, multistep pathologic process in which inflammation-related signals play a pivotal role. This new mouse model is an important asset for future clinical and therapeutic investigations of NF1-associated neurofibromas. SIGNIFICANCE: Patients affected by NF1 develop numerous cNFs. We present a mouse model that faithfully recapitulates cNFs, identify a candidate cell type at their origin, analyze the steps involved in their formation, and show that their development is dramatically accelerated by skin injury. These findings have important clinical/therapeutic implications.This article is highlighted in the In This Issue feature, p. 1.

Spatiotemporal Loss of NF1 in Schwann Cell Lineage Leads to Different Types of Cutaneous Neurofibroma Susceptible to Modification by the Hippo Pathway.

Neurofibromatosis type 1 (NF1) is a cancer predisposition disorder that results from inactivation of the tumor suppressor neurofibromin, a negative regulator of RAS signaling. Patients with NF1 present with a wide range of clinical manifestations, and the tumor with highest prevalence is cutaneous neurofibroma (cNF). Most patients harboring cNF suffer greatly from the burden of those tumors, which have no effective medical treatment. Ironically, none of the numerous NF1 mouse models developed so far recapitulate cNF. Here, we discovered that HOXB7 serves as a lineage marker to trace the developmental origin of cNF neoplastic cells. Ablating Nf1 in the HOXB7 lineage faithfully recapitulates both human cutaneous and plexiform neurofibroma. In addition, we discovered that modulation of the Hippo pathway acts as a "modifier" for neurofibroma tumorigenesis. This mouse model opens the doors for deciphering the evolution of cNF to identify effective therapies, where none exist today. SIGNIFICANCE: This study provides insights into the developmental origin of cNF, the most common tumor in NF1, and generates the first mouse model that faithfully recapitulates both human cutaneous and plexiform neurofibroma. The study also demonstrates that the Hippo pathway can modify neurofibromagenesis, suggesting that dampening the Hippo pathway could be an attractive therapeutic target.This article is highlighted in the In This Issue feature, p. 1.

Not so mass effect? Finding of a remarkable 'incidentaloma' in a teenager with neurofibromatosis.

A 13-year-old boy with neurofibromatosis type 1 presented to the emergency department twice in a fortnight with moderate intermittent abdominal pain, radiating to the back and associated with nausea and vomiting. He examined as a well child with a soft abdomen and minimal tenderness. A history of constipation was identified but he failed to respond to a trial of laxatives. Subsequent ultrasound abdomen demonstrated a large mass surrounding the porta hepatis. MRI further characterised a focal, non-aggressive lesion extending from his liver, encapsulating his pancreas, portal vessels and laterally displacing his spleen and left kidney. Biopsy performed at a specialist cancer treatment hospital of our reference later confirmed this to be a benign neurofibroma of a size not previously reported in the literature. He will be managed conservatively with surveillance imaging and the potential for chemotherapy should the lesion continue to grow.

Human stem cell modeling in neurofibromatosis type 1 (NF1).

The future of precision medicine is heavily reliant on the use of human tissues to identify the key determinants that account for differences between individuals with the same disorder. This need is exemplified by the neurofibromatosis type 1 (NF1) neurogenetic condition. As such, individuals with NF1 are born with a germline mutation in the NF1 gene, but may develop numerous distinct neurological problems, ranging from autism and attention deficit to brain and peripheral nerve sheath tumors. Coupled with accurate preclinical mouse models, the availability of NF1 patient-derived induced pluripotent stem cells (iPSCs) provides new opportunities to define the critical factors that underlie NF1-associated nervous system disease pathogenesis and progression. In this review, we discuss the generation and potential applications of iPSC technology to the study of NF1.

[Lisch nodule in neurofibromatosis type 1]. / Nodules de lisch dans la neurofibromatose type 1.

Neurofibromatosis type 1 (NF1) or Von Recklinghausen disease manifests as cutaneous café-au-lait spots and neurofibromas. It is one of the most common autosomal dominant genetic diseases. It is extremely variable in its individual manifestation. Cutaneous and neurologic symptoms are the most common manifestations but it can also affect other organs including eyes, bones and other areas. Lisch nodules are the most common ocular manifestations in NF-1. They are asymptomatic small pigmented iris tumors (iris hamartomas) which can help suggest the diagnosis of NF1 as they are characteristic of this disease and mostly occur in adult patients. We report the case of a 45-year old female patient followed for a neurofibromatosis type 1 retained on the presence of multiple cutaneous café-au-lait spots and neurofibromas. Ophthalmologic examination showed visual acuity of 10/10 P3 in both eyes. Biomicroscopic examination showed Lisch nodules of the iris in both eyes (A,B).

Radiation-Induced Schwannomas and Neurofibromas: A Systematic Review.

OBJECTIVE: Radiation-induced benign peripheral nerve sheath tumors are uncommon late complications of irradiation. We conducted the largest systematic review of individual patient data. METHODS: We performed a systematic search of PubMed databases and compiled a comprehensive literature review. Kaplan-Meier analysis was used to investigate survival, and statistical significance was assessed with a log-rank test. RESULTS: We analyzed 40 cases of radiation-induced benign peripheral nerve sheath tumors. The histologic distributions were 28 schwannomas, 11 neurofibromas, and 1 ganglioneuroma. The average age of radiation exposure for development of primary lesions was 14.9 ± 15.5 years, and the latency period between radiotherapy to the onset of secondary tumors was 24.5 ± 12.7 years. The average irradiation dose delivered was 26.3 ± 20.3 Gy. The median overall survival for all cases was not reached (95% confidence interval, 22-not reached) months, with 10-year survival rates of 65.2%. Surgical negative margin was a positive prognostic factor for radiation-induced benign peripheral nerve sheath tumors. CONCLUSIONS: The risk of incidence of secondary benign peripheral nerve sheath tumors in patients treated with radiotherapy should be considered in long-term follow-up periods. At present, complete surgical resection is the main stay for the treatment of radiation-induced benign peripheral nerve sheath tumors.

Does Schwann cell dedifferentiation originate dermal neurofibromas?

Dermal neurofibromas are characteristic of neurofibromatosis type one (NF1), and their developmental origin still unsolved. Although NF1 loss is required for neurofibroma initiation, some features of these benign tumors resemble a skin injury state and cutaneous trauma or other insults might support tumor development. Since adult terminal Schwann cells ensheathing nerve endings are able to dedifferentiate into a progenitor-like state in response to nerve crushing, we hypothesized that dedifferentiation of NF1-/- Schwann cells could be at the origin of human dermal neurofibromas. In support of this, here we show that CDH19 (a marker specific of Schwann cell precursors) and Schwann cell dedifferentiation marker SOX2 are significantly upregulated in NF1 tumors. We posit that onset of nerve regeneration might have a role in dermal neurofibroma initiation via dedifferentiation of NF1-/- Schwann cells.

Paraspinal neurofibromas and hypertrophic neuropathy in Noonan syndrome with multiple lentigines.

BACKGROUND: Noonan syndrome with multiple lentigines (NSML), formerly known as LEOPARD syndrome, is an autosomal-dominant disorder characterised by lentigines, EKG abnormalities, ocular hypertelorism, pulmonic stenosis, abnormal genitalia, growth retardation and deafness. There is significant clinical overlap between NSML and other disorders that result from dysregulated rat sarcoma/mitogen-activated protein kinase pathway (RASopathies). Except for neurofibromatosis type 1, other RASopathies are not known to be typically associated with neurogenic tumours. METHODS AND RESULTS: We evaluated patients from three families with pigmentary skin lesions, progressive neuropathy, enlarged nerves, massive burden of paraspinal tumours (neurofibroma was confirmed in one patient) and a clinical diagnosis of NSML. All patients had a mutation in the protein tyrosine phosphatase catalytic domain of the PTPN11 gene; two unrelated patients had the p.Thr468Met mutation, while the family consisting of two affected individuals harboured the p.Thr279Cys mutation. Molecular analysis performed on hypertrophic nerve tissue did not disclose a second somatic hit in NF1, PTPN11, NF2 or SMARCB1 genes. CONCLUSIONS: Neurogenic tumours and hypertrophic neuropathy are unusual complications of NSML and may be an under-recognised manifestation that would warrant surveillance. Our observation may also have implications for other disorders caused by RAS-pathway dysregulation.

Solitary Neurofibroma Of The Spermatic Cord: A Case Report.

We report the ultrasound, computerized tomography, positron emission tomography and magnetic resonance imaging findings of a 38-year-old man with a biopsy proven solitary neurofibroma of the spermatic cord. Solitary neurofibromas of the male genital tract are exceedingly rare benign peripheral nerve sheath neoplasms composed of Schwann cells and fibroblasts. In contrast to schwannomas they are not bound by a capsule thus allowing infiltration between the nerve fascicles. Although they are benign lesions whose potential for malignant degeneration is very low, especially in the absence of neurofibromatosis type 1, accurate diagnosis is important as neurofibromas in this location can cause significant morbidity and psychological distress. Despite the extensive differential diagnosis of masses in the male inguinal canal, including both benign and malignant entities, a diagnosis of benign peripheral nerve sheath tumor can be potentially suggested based on imaging, particularly if MRI is performed. Surgical resection is the treatment of choice and the final diagnosis should be provided by histopathology, as was the case with this patient.

Radiation induced malignant peripheral nerve sheath tumour of the second cervical nerve.

We report a 44-year-old with progressive quadriparesis due to a dumbbell malignant peripheral nerve sheath tumour (MPNST) of the second cervical nerve, 17 years after whole brain radiotherapy for a pineal germinoma. To our knowledge this is the first case of radiation induced high cervical MPNST arising from a benign neurofibroma.

Solitary giant neurofibroma of the mental nerve: a trauma-related lesion?

Neurofibroma is a benign neoplasm derived from peripheral nerves whose etiology is still unclear. It may present as a solitary lesion or be associated with other diseases such as neurofibromatosis type I and II syndrome. This paper aims to report an extremely rare case of a solitary giant neurofibroma of the mental nerve whose etiology was related to a local trauma. A 14-year-old female patient presented an extensive left facial mass with a size of 7 × 5 × 4 cm, located between the teeth 33 and 37 in the mandible region. It has begun to grow 3 months after a local trauma. Imaging studies were suggestive of a soft-tissue lesion, with minimal bone changes and maintaining the integrity of the mandibular canal and mental foramen. Histopathological tests showed spindle cells with undulated and hyperchromatic nuclei, and sparse cytoplasm in a stroma composed of dense fibrous connective tissue. Immunohistochemistry revealed positive expression for the proteins S-100 and vimentin, confirming the diagnosis of neurofibroma. The patient underwent surgical removal of the lesion by intraoral approach and evolved with an excellent cosmetic result and no signs of recurrence after 2 years of follow up. We report a rare case of solitary giant neurofibroma whose etiology was related to a local trauma. To our knowledge, this is the first report of a mental nerve neurofibroma. Although the etiology remains unclear, we suggest the investigation of local trauma as a possible etiologic factor for solitary neurofibromas of the jaw.