A case of multiple cutaneous schwannomas; schwannomatosis or neurofibromatosis type 2?

Schwannoma of the left foot: a brief overview with focus on associated clinical syndromes

In this article, we present a 25-year-old man who developed an asymptomatic schwannoma on his left lateral heel and review the salient features of this cutaneous condition. A schwannoma is a slowly growing neoplasm of Schwann cell origin. Histology shows high cellularity (Antoni A regions), nuclear palisades (Verocay bodies), and alternating myxoid regions (Antoni B regions). Very few cases have been reported on the foot or ankle. As with this patient, most schwannomas do not cause symptoms, but some result in dysesthesia and nerve dysfunction. Multiple schwannomas may indicate an underlying syndrome such as neurofibromatosis type 1, type 2, and schwannomatosis. The differential diagnosis for schwannoma includes fibrosarcoma, leiomyosarcoma, and neurofibroma. The definitive treatment is surgical excision. This usually results in complete resolution with minimal recurrence, as was the case for this patient.

Neurofibromatosis Type 2 Presenting with Oculomotor Ophthalmoplegia and Distal Myopathy

Neurofibromatosis type 2 usually presents with bilateral acoustic schwannomas. We highlight the rare presentation of neurofibromatosis initially involving third nerve. A 23-year-old Malay female presented with left eye drooping of the upper lid and limitation of upward movement for 8 years. It was associated with right-sided body weakness, change in voice, and hearing disturbance in the right ear for the past 2 years. On examination, there was mild ptosis and limitation of movement superiorly in the left eye. Both eyes had posterior subcapsular cataract. Fundoscopy showed generalised optic disc swelling in both eyes. She also had palsy of the right vocal cord, as well as the third and eighth nerve. There was wasting of the distal muscles of her right hand, with right-sided decreased muscle power. Pedunculated cutaneous lesions were noted over her body and scalp. MRI revealed bilateral acoustic and trigeminal schwannomas with multiple extra-axial lesions and intradural extramedullary nodules. Patient was diagnosed with neurofibromatosis type 2 and planned for craniotomy and tumour debulking, but she declined treatment. Neurofibromatosis type 2 may uncommonly present with isolated ophthalmoplegia, so a thorough physical examination and a high index of suspicion are required to avoid missing this condition.

Neurofibromatosis type 2 (NF 2) or schwannomatosis?--Case report study and diagnostic criteria

INTRODUCTION

Neurofibromatosis type 2 (NF2) and schwannomatosis are entities that may, due to the similarity of clinical symptoms, cause diagnostic difficulties. Incidence rate of both diseases is similar and estimated between 1:25,000 and 1:40,000. The genes associated with the development of the aforementioned disorders are located on chromosome 22 and lay in proxmity. Schwannomatosis is characterized by an incomplete penetrance and the risk of its transmission to the offspring is significantly lower than in the case of NF 2. Schwannomatosis clinical characteristic is similar to the NF2, however vestibular schwannomas are not present. Therefore the imaging studies evaluated by an experienced radiologist play a key role in the diagnostic process.

CASE REPORT

Forty two-year-old female hospitalized three times because of the tumors of the spinal canal was admitted to the Department of Neurosurgery and Peripheral Nerve Surgery in 2008 because of the cervical pain syndrome with concomitant headache. She was diagnosed with a schwannomatosis, recently distinguished, the third form of neurofibromatosis. MRI imaging revealed craniocervical junction tumor. Suboccipital craniectomy with concomitant C1-C2 laminectomy was done in order to remove the lesion. After the surgery the patient did not present any deficits in neurological examination and was discharged from hospital in good general condition.

CONCLUSIONS

The patient was diagnosed with schwannomatosis, recently established neurofibromatosis entity which may resemble NF2 clinically. In patients after the age of 30, in whom we observe multiple schwannomas without the concomitant hearing impairment, the diagnosis of schwannomatosis is very likely.

Management of multiple tumors in neurofibromatosis type 2 patients

INTRODUCTION

Neurofibromatosis type 2 is characterized by the presence of bilateral vestibular schwannomas. However, other nervous system tumors may also occur. Therefore, the management of NF2 patients is complex and requires a multidisciplinary discussion in a specialized center.

MATERIALS AND METHODS

All recent articles concerning tumors other than vestibular schwannoma in NF2 disease were reviewed, using PubMed databases.

RESULTS

Intracranial meningiomas occur in 50% of NF2 patients, and are often multiple. Surgery remains the main treatment and should be performed in cases of growing tumors. The role of antiangiogenic therapy is currently under evaluation and the role of radiosurgery still remains to be defined in NF2 disease. Spinal tumors occur in about half of NF2 patients. Surgery should be discussed when radiological tumor progression is demonstrated, even if spinal tumors are asymptomatic, in order to preserve neurological function and good quality of life. As regards lower cranial nerve schwannomas, radiosurgery appears to be a more appropriate treatment for growing tumor with a small volume in order to avoid post-operative complications, especially swallowing disorders. Facial nerve schwannomas may appear, on MRI, like vestibular schwannomas. The diagnosis should be suspected when the facial palsy is an early symptom during cerebello-pontine tumor progression. Trigeminal schwannomas are frequent in NF2 disease and fortunately they are often asymptomatic. Among major neurofibromatosis types, peripheral nerve sheath schwannomas are only present in patients with NF2 disease and schwannomatosis. Surgical resection is required when the cutaneous schwannomas is painful or when tumor progression is observed and causes symptoms.

CONCLUSION

Tumors other than vestibular schwannoma are also associated with a poor prognosis in NF2 patients. Surgery remains the main treatment in most cases. Each treatment decision in NF2 disease requires a complete evaluation of all cranial and spinal locations of the disease in order to establish surgical priorities and strategies.

Schwannomatosis on a single foot: a case report

Schwannomatosis has been recently recognized as the third major type of neurofibromatosis. It causes multiple schwannomas without the vestibular tumors that are diagnostic of neurofibromatosis type 2. Schwannoma is rarely found in the foot, and it is still rarer to find multiple schawannomas in a single peripheral nerve on the foot. In this article, we describe a case of schwannomatosis case on a single foot.

LEVELS OF EVIDENCE

Case report, Level IV.

Segmental neurofibromatosis type 2: discriminating two hit from four hit in a patient presenting multiple schwannomas confined to one limb

Background

A clinical overlap exists between mosaic Neurofibromatosis Type 2 and sporadic Schwannomatosis conditions. In these cases a molecular analysis of tumors is recommended for a proper genetic diagnostics. This analysis is challenged by the fact that schwannomas in both conditions bear a somatic double inactivation of the NF2 gene. However, SMARCB1-associated schwannomas follow a four-hit, three-step model, in which both alleles of SMARCB1 and NF2 genes are inactivated in the tumor, with one of the steps being always the loss of a big part of chromosome 22 involving both loci.

Case presentation

Here we report a 36-year-old woman who only presented multiple subcutaneous schwannomas on her right leg. To help discriminate between both possible diagnoses, an exhaustive molecular genetic and genomic analysis was performed on two schwannomas of the patient, consisting in cDNA and DNA sequencing, MLPA, microsatellite multiplex PCR and SNP-array analyses. The loss of a big part of chromosome 22 (22q12.1q13.33) was identified in both tumors. However, this loss involved the NF2 but not the SMARCB1 locus. SNP-array analysis revealed the presence of the same deletion breakpoint in both schwannomas, indicating that this alteration was actually the first NF2 inactivating hit. In addition, a distinct NF2 point mutation in each tumor was identified, representing independent second hits. In accordance with these results, no deletions or point mutations in the SMARCB1 gene were identified. None of the mutations were present in the blood. Two of the patient’s children inherited chromosome 22 deleted in schwannomas of the mother, but in its wild type form.

Conclusions

These results conclusively confirm the segmental mosaic NF2 nature of the clinical phenotype presented.

SMARCB1 mutations in schwannomatosis and genotype correlations with rhabdoid tumors

Mutations in the SMARCB1 gene are involved in several human tumor-predisposing syndromes. They were established as an underlying cause of the tumor suppressor syndrome schwannomatosis in 2008. There is a much higher rate of mutation detection in familial disease than in sporadic disease. We have performed extensive genetic testing on a cohort of familial and sporadic patients who fulfilled clinical diagnostic criteria for schwannomatosis. In our updated cohort, we identified novel mutations within the SMARCB1 gene as well as several recurrent mutations. Of the schwannomatosis screens reported to date, including those in our updated cohort, SMARCB1 mutations have been found in 45% of familial probands and 9% of sporadic patients. The exon 1 mutation, c.41C>A p.Pro14His (10% in our series), and the 3' untranslated region mutation, c.*82C>T (27%), are the most common changes reported in patients with schwannomatosis to date, indicating the presence of mutation hot spots at both 5' and 3' portions of the gene. Comparison with germline SMARCB1 mutations in patients with rhabdoid tumors showed that the schwannomatosis mutations were significantly more likely to occur at either end of the gene and be nontruncating mutations (P < 0.0001). SMARCB1 mutations are found in a significant proportion of schwannomatosis patients, and an even higher proportion of rhabdoid patients. Whereas SMARCB1 alone seems to account for rhabdoid disease, there is likely to be substantial heterogeneity in schwannomatosis even for familial disease. There is a clear genotype-phenotype correlation, with germline rhabdoid mutations being significantly more likely to be centrally placed, involve multiple exon deletions, and be truncating mutations.

Schwannomas and their pathogenesis

Schwannomas may occur spontaneously, or in the context of a familial tumor syndrome such as neurofibromatosis type 2 (NF2), schwannomatosis and Carney's complex. Schwannomas have a variety of morphological appearances, but they behave as World Health Organization (WHO) grade I tumors, and only very rarely undergo malignant transformation. Central to the pathogenesis of these tumors is loss of function of merlin, either by direct genetic change involving the NF2 gene on chromosome 22 or secondarily to merlin inactivation. The genetic pathways and morphological features of schwannomas associated with different genetic syndromes will be discussed. Merlin has multiple functions, including within the nucleus and at the cell membrane, and this review summarizes our current understanding of the mechanisms by which merlin loss is involved in schwannoma pathogenesis, highlighting potential areas for therapeutic intervention.

Update from the 2011 International Schwannomatosis Workshop: From genetics to diagnostic criteria

Schwannomatosis is the third major form of neurofibromatosis and is characterized by the development of multiple schwannomas in the absence of bilateral vestibular schwannomas. The 2011 Schwannomatosis Update was organized by the Children's Tumor Foundation (www.ctf.org) and held in Los Angeles, CA, from June 5-8, 2011. This article summarizes the highlights presented at the Conference and represents the "state-of-the-field" in 2011. Genetic studies indicate that constitutional mutations in the SMARCB1 tumor suppressor gene occur in 40-50% of familial cases and in 8-10% of sporadic cases of schwannomatosis. Tumorigenesis is thought to occur through a four-hit, three-step model, beginning with a germline mutation in SMARCB1 (hit 1), followed by loss of a portion of chromosome 22 that contains the second SMARCB1 allele and one NF2 allele (hits 2 and 3), followed by mutation of the remaining wild-type NF2 allele (hit 4). Insights from research on HIV and pediatric rhabdoid tumors have shed light on potential molecular pathways that are dysregulated in schwannomatosis-related schwannomas. Mouse models of schwannomatosis have been developed and promise to further expand our understanding of tumorigenesis and the tumor microenvironment. Clinical reports have described the occurrence of intracranial meningiomas in schwannomatosis patients and in families with germline SMARCB1 mutations. The authors propose updated diagnostic criteria to incorporate new clinical and genetic findings since 2005. In the next 5 years, the authors expect that advances in basic research in the pathogenesis of schwannomatosis will lead toward clinical investigations of potential drug therapies.

Malignant peripheral nerve sheath tumours in inherited disease

Background

Malignant peripheral nerve sheath tumours (MPNST) are rare tumours known to occur at high frequency in neurofibromatosis 1 (NF1), but may also occur in other cancer prone syndromes.

Methods

The North West Regional Genetic Register covers a population of 4.1 million and was interrogated for incidence of MPNST in 12 cancer prone syndromes. Age, incidence and survival curves were generated for NF1.

Results

Fifty two of 1254 NF1 patients developed MPNST, with MPNST also occurring in 2/181 cases of schwannomatosis and 2/895 NF2 patients. Three cases were also noted in TP53 mutation carriers. However, there were no cases amongst 5727BRCA1/2 carriers and first degree relatives, 2029 members from Lynch syndrome families, nor amongst 447 Familial Adenomatous Polyposis, 202 Gorlin syndrome, nor 87 vHL cases.

Conclusion

MPNST is associated with schwannomatosis and TP53 mutations and is confirmed at high frequency in NF1. It appears to be only increased in NF2 amongst those that have been irradiated. The lifetime risk of MPNST in NF1 is between 9–13%.

Clinical features of schwannomatosis: a retrospective analysis of 87 patients

BACKGROUND

Schwannomatosis is a recently recognized form of neurofibromatosis characterized by multiple noncutaneous schwannomas, a histologically benign nerve sheath tumor. As more cases are identified, the reported phenotype continues to expand and evolve. We describe the spectrum of clinical findings in a cohort of patients meeting established criteria for schwannomatosis.

METHODS

We retrospectively reviewed the clinical records of patients seen at our institution from 1995-2011 who fulfilled either research or clinical criteria for schwannomatosis. Clinical, radiographic, and pathologic data were extracted with attention to age at onset, location of tumors, ophthalmologic evaluation, family history, and other stigmata of neurofibromatosis 1 (NF1) or NF2.

RESULTS

Eighty-seven patients met the criteria for the study. The most common presentation was pain unassociated with a mass (46%). Seventy-seven of 87 (89%) patients had peripheral schwannomas, 49 of 66 (74%) had spinal schwannomas, seven of 77 (9%) had nonvestibular intracranial schwannomas, and four of 77 (5%) had intracranial meningiomas. Three patients were initially diagnosed with a malignant peripheral nerve sheath tumor; however, following pathologic review, the diagnoses were revised in all three cases. Chronic pain was the most common symptom (68%) and usually persisted despite aggressive surgical and medical management. Other common diagnoses included headaches, depression, and anxiety.

CONCLUSIONS

Peripheral and spinal schwannomas are common in schwannomatosis patients. Severe pain is difficult to treat in these patients and often associated with anxiety and depression. These findings support a proactive surveillance plan to identify tumors by magnetic resonance imaging scan in order to optimize surgical treatment and to treat associated pain, anxiety, and depression.

Frequency of SMARCB1 mutations in familial and sporadic schwannomatosis

Mutations of the SMARCB1 gene have been implicated in several human tumour predisposing syndromes. They have recently been identified as an underlying cause of the tumour suppressor syndrome schwannomatosis. There is a much higher rate of mutation detection in familial disease than in sporadic disease. We have carried out extensive genetic testing on a cohort of familial and sporadic patients who fulfilled clinical diagnostic criteria for schwannomatosis. In our current cohort, we identified novel mutations within the SMARCB1 gene and detected several mutations that have been previously identified in other schwannomatosis cohorts. Of the schwannomatosis screens reported to date, including our current dataset, SMARCB1 mutations have been found in 45 % of familial probands and 7 % of sporadic patients. The exon 1 mutation, c.41C >A, and the 3' untranslated region mutation, c.*82C >T, are the most common changes reported in schwannomatosis disease so far, indicating mutation hotspots at both 5' and 3' portions of the gene. SMARCB1 mutations are found in a significant proportion of schwannomatosis patients, but there remains the possibility that further causative genes remain to be found.

Vestibular schwannomas occur in schwannomatosis and should not be considered an exclusion criterion for clinical diagnosis

Schwannomatosis is a recently delineated inherited condition that has clinical overlap with neurofibromatosis type 2 (NF2). Diagnostic criteria have been developed to distinguish schwannomatosis from NF2, but the existence of mosaic NF2, which may closely mimic schwannomatosis, makes even these criteria problematic. In particular, it is not clear why there is a relative sparing of the cranial nerves from schwannomas in schwannomatosis. We have identified two individuals with schwannomatosis and a unilateral vestibular schwannoma (VS), where a diagnosis of NF2 has been excluded. A third case with an identified SMARCB1 mutation was reported by two radiologists to have a VS, but this was later confirmed as a jugular schwannoma. These cases question whether the current exclusion of a VS from the clinical diagnosis of schwannomatosis is justified.

Neurofibromatosis 2 [Bilateral acoustic neurofibromatosis, central neurofibromatosis, NF2, neurofibromatosis type II]

Neurofibromatosis 2 is a dominantly inherited tumor predisposition syndrome caused by mutations in the NF2 gene on chromosome 22. Affected individuals inevitably develop schwannomas typically affecting both vestibular nerves leading to deafness. Rehabilitation with brainstem implants is improving this outcome. Schwannomas also occur on other cranial nerves, on spinal nerve roots, and on peripheral nerves. Meningiomas and ependymomas are other tumor features. In excess of 50% of patients represent new mutations and as many as one third are mosaic for the underlying disease causing mutation. Although truncating mutations (nonsense and frameshifts) are the most frequent germline event and cause the most severe disease, single and multiple exon deletions are common. A strategy for detection of the latter is vital for a sensitive analysis. NF2 represents a difficult management problem with most patients facing substantial morbidity and reduced life expectancy. Surgery remains the focus of current management, although watchful waiting and occasionally radiation treatment have a role. In the future, the development of tailored drug therapies aimed at the genetic level are likely to provide huge improvements for this devastating, life limiting condition.

Mosaicism in neurofibromatosis type 2: an update of risk based on uni/bilaterality of vestibular schwannoma at presentation and sensitive mutation analysis including multiple ligation-dependent probe amplification

BACKGROUND

Neurofibromatosis type 2 (NF2) is almost unique among inherited disorders in the frequency of mosaicism in the first affected generation. However, the implications of this on transmission risks have not been fully elucidated.

METHODS

The expanded database of 460 families with NF2 and 704 affected individuals was analysed for mosaicism and transmission risks to offspring.

RESULTS

64 mosaic patients, with a projected mosaicism rate of 33% for sporadic classical NF2 with bilateral vestibular schwannoma at presentation and 60% for those presenting unilaterally, were identified. Offspring risks can be radically reduced on the basis of a sensitive mutation analysis of blood DNA including multiple ligation-dependent probe amplification (MLPA, which detects 15% of all mutations), but even MLPA cannot detect high levels of mosaicism.

CONCLUSION

The chances of mosaicism in NF2 and the resultant risks of transmission of the mutation to offspring in a number of different clinical situations have been further delineated. The use of MLPA in this large NF2 series is also reported for the first time.

News on the genetics, epidemiology, medical care and translational research of Schwannomas

Recent years have seen substantial news and updates in the genetics and diagnosis of schwannomas, even a new hereditary disease with schwannomas; Schwannomatosis has been defined. These developments have consequently led to better evaluation of the incidence of schwannomas. Although there has also been progress in the treatment of schwannomas especially in the field of radiation therapy, hereditary diseases with multiple tumours still represent a therapeutic dilemma. NF2 in particular still causes major morbidity and mortality owing to the neurological deficit of multiple tumour disease and deafness caused by vestibular nerve involvement. Thus there has been great enthusiasm about disease models in the hope that translational research will give rise to new therapies.

Neurofibromatosis type 2: a case of ptosis

BACKGROUND

Neurofibromatosis type 2 (NF2) is a disorder usually diagnosed later in life since the features are subtle in children. The hallmark is bilateral vestibular schwannomas, which may not appear until after the second decade. Other cranial nerve schwannomas occur as well. In addition, there may be schwannomas of spinal nerve roots or peripheral nerves, as well as meningiomas, gliomas, and ependymomas. Here is described a rare case of NF2 associated with a superior rectus muscle paralysis and severe ptosis. A complex surgical procedure, which achieved satisfactory results, is also described.

CASE REPORT

A 17-year-old patient with NF2 was referred to us with diagnosis of left-eye superior rectus muscle paralysis, with a later onset of unilateral severe ptosis. Best-corrected visual acuity was 20/20 in both eyes; pupillary reflexes to light and near vision were normal, and subcapsular posterior opacity of the lens was detected. Eye motility examination confirmed a left-eye superior rectus paralysis and a severe ptosis with almost absent palpebral levator muscle function. The patient showed positive familiar history for NF (the father was affected), bilateral involvement of the acoustic nerves (schwannoma), multiple neurofibromas, and bilateral posterior subcapsular lens opacity. Magnetic resonance imaging (MRI) showed bilateral acoustic neuromas in the left temporal region close to the cavernous sinus; since neurological examination and ocular motility problems had remained stationary over time, surgical correction of ptosis and strabismus was suggested.

CONCLUSION

Palpebral ptosis has rarely been reported in NF2. In the case described, ptosis associated with rectus superior palsy was caused by expansive processes in the temporal region close to the cavernous sinus. In order to resolve ptosis and vertical diplopia, we performed a complex surgery that achieved satisfactory results.