The Neurofibromatoses

Raman difference spectroscopy and U-Net convolutional neural network for molecular analysis of cutaneous neurofibroma

In Neurofibromatosis type 1 (NF1), peripheral nerve sheaths tumors are common, with cutaneous neurofibromas resulting in significant aesthetic, painful and functional problems requiring surgical removal. To date, determination of adequate surgical resection margins-complete tumor removal while attempting to preserve viable tissue-remains largely subjective. Thus, residual tumor extension beyond surgical margins or recurrence of the disease may frequently be observed. Here, we introduce Shifted-Excitation Raman Spectroscopy in combination with deep neural networks for the future perspective of objective, real-time diagnosis, and guided surgical ablation. The obtained results are validated through established histological methods. In this study, we evaluated the discrimination between cutaneous neurofibroma (n = 9) and adjacent physiological tissues (n = 25) in 34 surgical pathological specimens ex vivo at a total of 82 distinct measurement loci. Based on a convolutional neural network (U-Net), the mean raw Raman spectra (n = 8,200) were processed and refined, and afterwards the spectral peaks were assigned to their respective molecular origin. Principal component and linear discriminant analysis was used to discriminate cutaneous neurofibromas from physiological tissues with a sensitivity of 100%, specificity of 97.3%, and overall classification accuracy of 97.6%. The results enable the presented optical, non-invasive technique in combination with artificial intelligence as a promising candidate to ameliorate both, diagnosis and treatment of patients affected by cutaneous neurofibroma and NF1.

Bilateral Inferior Rectus Schwannoma and Strabismus: A Case Report

Schwannomas, also known as neurilemomas, are peripheral nerve sheath neoplasms. They can be sporadic or associated with genetic syndromes including neurofibromatosis type 2 (NF2). Schwannomas may lead to symptoms by exerting pressure on nearby structures, such as nerve and muscle fibers. In this study, we present the case of a 22-year-old female with a history of NF2 who, upon examination, presented with a visibly enlarged salmon-colored mass involving the left inferior rectus that she had since the age of 12 years. Ocular examinations revealed a small left hypertropia and exotropia in all gazes. Magnetic resonance imaging confirmed bilateral involvement of the inferior rectus muscles. She had a partial excisional biopsy of the mass involving the left inferior rectus muscle that confirmed the presence of schwannoma. This case highlights the importance of comprehensive evaluation of sensory and motor functions as well as considering orbital schwannomas in cases of strabismus, especially within the context of neurofibromatosis.

A Rare Case Report of Neonatal Neurofibromatosis Type 1 Presented with Giant Faciocervical Mass and Complicated with HIE

A newborn with giant faciocervical mass and presented with asphyxia during birth was admitted to the hospital. After stabilizing her vital sign, we provided the patient with image examinations and whole-exome sequencing, which revealed a heterozygous variation of neurofibromatosis type 1 (NF1). The final diagnosis of the patient was NF1 complicated with neonatal hypoxic-ischemic encephalopathy (NHIE). During hospitalization, the patient received comprehensive and systematic care. There was no reports of similar cases in the literature. So, this report aimed to elucidate the special clinical manifestations, diagnosis, treatment and prognosis of NF1 complicated with NHIE by analyzing the clinical data of the patient and her family and reviewing relevant literature.

Late-Onset Masseteric Metastasis of Malignant Melanoma in a Patient With Neurofibromatosis and Lipomatosis: A Diagnostic Challenge and Case Report

Melanoma and neurofibromatosis (NF) are distinctly separate conditions, each characterized by unique pathophysiological processes. Nevertheless, their clinical presentations can share overlapping similarities. This report highlights a unique case involving a 68-year-old male with NF1 and lipomatosis, whose unwavering belief that a developing mass in the masseter region was benign and linked to the pre-existing diagnoses contributed to a significant delay in seeking healthcare. Consequently, this postponement resulted in the late diagnosis of disseminated malignant melanoma (stage IV, T4N0M1c). Given the patient's prognosis and poor general health, a palliative treatment plan was devised, entailing the complete excision of the masseteric mass and vertebral radiotherapy. Following a rapid and extensive progression of the cancerous lesions, the patient passed away in a palliative care infirmary four months after surgery. The significance of this case, justified not only by its uncommon presentation and atypical differential diagnosis, highlights the critical necessity of regular follow-up protocols for melanoma patients, particularly those prone to metastasis, while ensuring patient attendance. Furthermore, it underscores the necessity of patient education, particularly in recognizing early signs and symptoms, and timely intervention in cases with complex comorbidities.

The role of neuromuscular ultrasound in diagnostics of peripheral neuropathies induced by cytostatic agents or immunotherapies

A relevant number of cancer patients who receive potentially neurotoxic cytostatic agents develop a chemotherapy-induced peripheral neuropathy over time. Moreover, the increasing use of immunotherapies and targeted agents leads to a raising awareness of treatment-associated peripheral neurotoxicity, e.g., axonal and demyelinating neuropathies such as Guillain-Barré-like syndromes. To date, the differentiation of these phenomena from concurrent neurological co-morbidities or (para-)neoplastic nerve affection as well as their longitudinal monitoring remain challenging. Neuromuscular ultrasound (NMUS) is an established diagnostic tool for peripheral neuropathies. Performed by specialized neurologists, it completes clinical and neurophysiological diagnostics especially in differentiation of axonal and demyelinating neuropathies. No generally approved biomarkers of treatment-induced peripheral neurotoxicity have been established so far. NMUS might significantly extend the repertoire of diagnostic and neuromonitoring methods in this growing patient group in short term. In this article, we present enlargements of the dorsal roots both in cytostatic and in immunotherapy-induced neurotoxicity for the first time. We discuss related literature regarding new integrative applications of NMUS for cancer patients by reference to two representative case studies. Moreover, we demonstrate the integration of NMUS in a diagnostic algorithm for suspected peripheral neurotoxicity independently of a certain cancer treatment regimen emphasizing the emerging potential of NMUS for clinical routine in this interdisciplinary field and prospective clinical trials.

Case Report: Multiple gastrointestinal stromal tumors along with numerous cutaneous neurofibromas: a case description and literature analysis

Multiple gastrointestinal stromal tumors (GISTs) combined with cutaneous multiple neurofibromas are clinically rare. This paper presents a case of multiple gastrointestinal stromal tumors in the jejunum of a 68-year-old mother, along with her daughter who also had coexisting cutaneous multiple neurofibromas. The mother had been experiencing repeated melena for over 2 years and had previously been diagnosed with multiple small intestinal masses at other hospitals. Additionally, her 42-year-old daughter was admitted to our department due to recurrent abdominal pain caused by cholecystolithiasis. The mother and daughter both exhibited multiple nodular masses of varying sizes on their skin, including the truncus, limbs, and face, which were diagnosed as neurofibromas. The mother underwent a partial excision of the jejunum and a lateral jejunojejunal anastomosis side-to-side, as well as excision of skin lesions in our department. The final diagnosis of wild-type GISTs associated with neurofibromatosis type 1 (NF1) was confirmed through postoperative pathology, immunohistochemistry, and genetic testing results. During preoperative gastrointestinal endoscopy and intraoperative laparoscopic exploration of the gastrointestinal tract, no obvious tumors were found in her daughter. A combination of patient observations and a review of relevant literature in the field suggests that when patients present with gastrointestinal symptoms and multiple irregular painless swellings in the skin, it is important to consider the possibility of an association with NF1 and GIST. Additionally, obtaining a detailed family history can save time and improve the diagnosis of patients with both NF1 and GIST. We recommend that even if there are no gastrointestinal manifestations of GISTs in the offspring of newly mutated NF1 patients, regular review of gastroenteroscopy, imaging examination, and long-term follow-up after middle age are still crucial for the early diagnosis and treatment of NF1-related GISTs.

[Neurofibromatosis type 1 associated with pheochromocytoma: a case report with a brief review of the literature]

We presented the clinical case of neurofibromatosis type 1 (NF-1) associated with pheochromocytoma (PHEO) in a man under 40 years old without family history. The diagnosis of NF-1 was established based on 4 signs of the disease (multiple café au lait macules, scoliotic changes in posture, the presence of multiple neurofibromas, Lisch nodules). The diagnosis of PHEO was determined by a significant increase of free metanephrin/normethanephrin levels in daily urine, a malignant CT phenotype of the right adrenal tumor, and confirmed by pathomorphological study. Genetic tests revealed a new mutation in one of the alleles of NF1 gene, a deletion of a 566 bp gene fragment, including exon 19 with a size of 73 bp. This mutation leads to splicing of exons 18 and 20, frameshift, and termination of protein synthesis. A study of the level of transcription of the genes associated with PHEO (RET, TMEM127, MAX, FGFR, MET, MERTK, BRAF, NGFR, Pi3, AKT, MTOR, KRAS, MAPK) was conducted, a statistically significant decrease in the level of transcription of the KRAS and BRAF genes and increase in the level of transcription of the TMEM127 gene in comparison with control samples have been detected. This case demonstrates the need for timely recognition of NF-1 for further appropriate patient's follow up and show the effectiveness of a multidisciplinary approach to the diagnosis and treatment of NF-1-associated catecholamine-secreting tumors.

Risk factors for intraoperative hemorrhage of Type I neurofibromatosis

INTRODUCTION

Neurofibromatosis (NF) is an inherited disease and a benign tumor originating from nerve sheath cells. Neurofibromatosis type I (NF1) is the most common type, and most cases are characterized by neurofibromas. Neurofibromas in NF1 are mainly treated by surgery. Our study explores the risk factors for intraoperative hemorrhage in Type I neurofibromatosis patients who underwent neurofibroma resection.

METHODS

A cross-sectional comparison of the patients who had undergone resection of neurofibroma for NF1. Data regarding patient characteristics and data about operative outcomes were recorded. The definition of intraoperative hemorrhage group was the intraoperative blood loss greater than 200 ml.

RESULTS

Of 94 eligible patients, 44 patients were in the hemorrhage group and 50 patients were in the non-hemorrhage group. Multiple logistic regression analysis demonstrated that the area of excision, classification, surgical site, primary surgical, and organ deformation were significant independent predictors of hemorrhage.

CONCLUSION

Early treatment can reduce the tumor cross-sectional area, avoid organ deformation, and reduce intraoperative blood loss. For plexiform neurofibroma or neurofibroma of the head and face, the amount of blood loss should be predicted correctly, and preoperative evaluation and blood preparation should be paid more attention to.

Diagnosis of neonatal neurofibromatosis type 1: a case report and review of the literature

BACKGROUND

Neurofibromatosis Type 1 (NF1) is a rare genetic disorder characterized with the development of multiple benign tumors on the nerves and skin.

CASE PRESENTATION

This report described a neonatal case with a large mass observed on the left side of the maxillofacial and cervical region at birth. Meantime, multiple cafe-au-lait macules (CALMs) were seen on the trunk and both lower extremities.

CONCLUSIONS

In this case, the clinical features of the rare NF1 neonate are discussed along with its ultrasound findings.

The German version of the neurofibromatosis 2 impact on quality of life questionnaire correlates with severity of depression and physician-reported disease severity

BACKGROUND

Neurofibromatosis type 2 (NF2) is a rare genetic disease that causes a wide range of disabilities leading to compromised quality of life (QOL). There is clear need for a validated disease-specific tool to assess quality of life among German-speaking patients with neurofibromatosis type 2 (NF2). The NFTI-QOL questionnaire has produced useful results in English-speaking cohorts. The aim of this study was to produce and validate a German version of the NFTI-QOL (NFTI-QOL-D) and to correlate QOL scores with a depression score (PHQ-9) and clinical disease severity.

METHODS

The original English-language NFTI-QOL was translated into German and then back-translated in order to preserve the questionnaire's original concepts and intentions. A link to an online survey encompassing the NFTI-QOL-D and the PHQ-9 depression questionnaire was then sent to 97 patients with NF2 by email. The respondents' scores were compared to clinician-reported disease severity scores.

RESULTS

77 patients completed the online survey in full. Internal reliability among NFTI-QOL-D responses was strong (Cronbach's alpha: 0.74). Both PHQ-9 and clinician disease severity scores correlated with NFTI-QOL-D scores (Pearson's rho 0.63 and 0.62, respectively).

CONCLUSIONS

The NFTI-QOL-D is a reliable and useful tool to assess patient-reported QOL in German-speaking patients with NF2. The correlation of QOL with both psychological and physical disease parameters underlines the importance of individualized interdisciplinary patient care for NF2 patients, with attention paid to mental well-being as well as to somatic disease manifestations.

Malignant anaplastic meningioma in neurofibromatosis type 1 patient: a rare case report

BACKGROUND

Meningiomas are usually associated with neurofibromatosis type 2 (NF-2), while gliomas are usually associated with neurofibromatosis type 1 (NF-1). NF-1 is an autosomal dominant genetic disorder associated with skin manifestations, bone conditions, and different types of benign and malignant tumors. Grade 3 anaplastic meningiomas are rare tumors with a poor prognosis. Systemic treatments in grade 3 meningiomas are experimental, with some reports suggestive of minimal clinical benefits. They are used occasionally for recurrent cases with no surgical or radiotherapy roles. In our case, we will focus the discussion on grade 3 anaplastic meningioma in a patient with NF-1, using chemotherapy for this aggressive, recurrent tumor. To our knowledge, this is the first case of NF-1 associated with malignant anaplastic meningioma in English literature.

CASE DESCRIPTION

In this case report, we present a 25-year-old left-handed female patient who fits the diagnostic criteria for NF-1. She presented with focal seizure and was diagnosed with grade 3 anaplastic meningioma, a highly aggressive tumor. She experienced a rapid recurrence after her initial surgery and eventually received multiple lines of treatments, including radiation and chemotherapy [temozolomide (TMZ)].

CONCLUSIONS

Systemic therapy in grade 3 meningiomas is still experimental and may have a slight clinical benefit. As a result, further prospective, multicentric studies are needed to ascertain these outcomes. Patients should be included in prospective trials because of the poor prognosis and aggressive nature of grade 3 meningiomas. In addition, discovering specific molecular biomarkers will allow us to suggest an individualized treatment. This case suggests that the differential diagnosis of a mass in a patient with NF-1 should include tumors known to be associated with the syndrome as well as sporadic, unrelated neoplasms.

Neurofibromatosis: New Clinical Challenges in the Era of COVID-19

Rare diseases constitute a wide range of disorders thus defined for their low prevalence. However, taken together, rare diseases impact a considerable percentage of the world population, thus representing a public healthcare problem. In particular, neurofibromatoses are autosomal-dominant genetic disorders that include type 1 neurofibromatosis (NF1), type 2 neurofibromatosis (NF2) and schwannomatosis. Each of the three types is a genetically distinct disease with an unpredictable clinical course and for which there is still no resolutive cure. Therefore, a personalized therapeutic approach directed at improving the symptomatology as well as the search for new pharmacological strategies for the management of neurofibromatosis represents a priority for positive outcomes for affected patients. The coronavirus disease 2019 (COVID-19) pandemic has severely affected health systems around the world, impacting the provision of medical care and modifying clinical surveillance along with scientific research procedures. COVID-19 significantly worsened exchanges between healthcare personnel and neurofibromatosis patients, precluding continuous clinical monitoring in specialized clinic centers. In this new scenario, our article presents, for the first time, a comprehensive literature review on the clinical challenges for neurofibromatosis clinical care and research during the COVID-19 pandemic health emergency. The review was performed through PubMed (Medline) and Google Scholar databases until December 2021.

Spatial Distribution and Long-Term Alterations of Peripheral Nerve Lesions in Schwannomatosis

Purpose To examine the spatial distribution and long-term alterations of peripheral nerve lesions in patients with schwannomatosis by in vivo high-resolution magnetic resonance neurography (MRN). Methods In this prospective study, the lumbosacral plexus as well as the right sciatic, tibial, and peroneal nerves were examined in 15 patients diagnosed with schwannomatosis by a standardized MRN protocol at 3 Tesla. Micro-, intermediate- and macrolesions were assessed according to their number, diameter and spatial distribution. Moreover, in nine patients, peripheral nerve lesions were compared to follow-up examinations after 39 to 71 months. Results In comparison to intermediate and macrolesions, microlesions were the predominant lesion entity at the level of the proximal (p < 0.001), mid- (p < 0.001), and distal thigh (p < 0.01). Compared to the proximal calf level, the lesion number was increased at the proximal (p < 0.05), mid- (p < 0.01), and distal thigh level (p < 0.01), while between the different thigh levels, no differences in lesion numbers were found. In the follow-up examinations, the lesion number was unchanged for micro-, intermediate and macrolesions. The diameter of lesions in the follow-up examination was decreased for microlesions (p < 0.01), not different for intermediate lesions, and increased for macrolesions (p < 0.01). Conclusion Microlesions represent the predominant type of peripheral nerve lesion in schwannomatosis and show a rather consistent distribution pattern in long-term follow-up. In contrast to the accumulation of nerve lesions, primarily in the distal nerve segments in NF2, the lesion numbers in schwannomatosis peak at the mid-thigh level. Towards more distal portions, the lesion number markedly decreases, which is considered as a general feature of other types of small fiber neuropathy.

Shear-Wave-Elastography in Neurofibromatosis Type I

Ultrasound shear wave elastography (SWE) is an increasingly used imaging modality that expands clinical ultrasound by measuring the elasticity of various tissues, such as the altered elasticity of tumors. Peripheral nerve tumors are rare, have been well-characterized by B-mode-ultrasound, but have not yet been investigated with SWE. Given the lack of studies, a first step would be to investigate homogeneous peripheral nerve tumors (PNTs), histologically neurofibromas or schwannomas, which can occur in multiple in neurofibromatosis type 1 and 2 (NF1 and 2), respectively. Hence, we measured shear wave velocity (SWV) in 30 PNTs of 11 patients with NF1 within the median nerve. The SWV in PNTs ranged between 2.8 ± 0.8 m/s and correlated with their width and approximate volume but not with their length or height. Furthermore, we determined the extent to which PNTs alter the SWV of the median nerve for three positions of the wrist joint: neutral (zero-degree), individual maximal flexion and maximal extension. Here, SWV was decreased in NF1 patients compared to age- and sex-matched controls (p = 0.029) during maximal wrist extension. We speculate that the presence of PNTs may have a biomechanical impact on peripheral nerves which has not been demonstrated yet.

Intradural Extramedullary Lesions in the Cervical Spine in Neurofibromatosis

BACKGROUND Neurofibromatosis (NF) is categorized into 3 diseases: neurofibromatosis type 1, type 2, and schwannoma. NF2 is associated with a mutation in gene 22q11.2. It is present in about 1/25 000 to 33 000 births, and it is passed in an autosomal dominant fashion. Diagnosis is made based on clinical and radiological features. A few clinical features have been characterized and included in the Manchester criteria. A few neurofibromatosis type 2 patients have been diagnosed with over 25 cervical lesions. We report a case of an intradural extramedullary cervical lesion in a patient later diagnosed with neurofibromatosis type 2. CASE REPORT The patient was 30-year-old man admitted through the emergency unit, presenting with gradual onset and progressive spastic quadriparesis of 6 months duration. An MRI spine showed intradural extramedullary masses in the right side of C4 and left side of C6. He underwent cervical intradural excision of 2 masses under general anesthesia with neuromonitoring. The tumor was sent to histopathology and reported as neurofibromatosis 2. CONCLUSIONS Neurofibromatosis is a common entity, but the diagnosis of a cervical mass is judicious to avoid any misfortune in neurological function. It requires a multidisciplinary approach and screening modalities.

Complications of Neurofibromatosis 1 (NF1) in an Adult With Multiple Comorbidities

Neurofibromatosis (NF) is an autosomal genetic disorder with three types, including NF1, NF2, and schwannomatosis. It is characterized by bulging and deforming masses arising from multiple nerves involving skin folds and connective tissues. Prompt diagnosis and provision of care for NF1 patients by clinicians aware of the diverse clinical features of this disorder are needed for optimum patient care and management. A 65-year-old African American female with a past medical history significant for multiple neurofibromas covering more than 95% of her total body surface area (TBSA), presented to a primary care clinic with an enlarged ulcerated neurofibroma of the right elbow. She reported associated pulsating, sharp pain, which was radiating to her entire right upper extremity. For most of her adult life, the lesion has been present and began as the rest of the neurofibromas on her body but gradually enlarged with eventual ulceration three months before the visit. The patient reported a failed surgical resection for the same neurofibroma several years ago. She also reported diffuse tenderness of the lesion, which severely impaired her daily living activities and limited her sleep ability. She acknowledged using multiple over-the-counter analgesics, prescription hydrocodone/acetaminophen 5/325 mg as needed, and gabapentin 300 mg orally twice daily but denied significant symptom alleviation. The patient was started on oral clindamycin hydrochloride 300 mg every six hours for 10 days and a topical mupirocin ointment 2% three times daily for five days. Subsequent visits showed no improvement of the ulcer, which necessitated a referral to wound care. After multiple wound care visits without progress, the patient was referred to a plastic surgeon for evaluation for repeat ulcer resection. NF1 patients develop multiple tumors (neurofibromas); approximately 8%-15% percent of them present with malignant peripheral nerve sheath tumors (MPNST) within the patient's lifetime. Tumor ulceration is a rare but possible complication of NF1. Due to the acute ulcerated fibromas' complications, previous unsuccessful cosmetic management, and ambiguity about NF1 disorder, the patient's quality of life was impaired. The physical and emotional pain the patient experienced impacted her activities of daily living and likely contributed to or exacerbated her diagnoses of substance use disorder and major depressive disorder. NF1 is incurable and can be associated with complications that deteriorate the quality of life, depending on symptom severity. The condition impacts patients' bodies, minds, and spirits, as seen in this patient who had diagnoses of substance use disorder and major depressive disorder, as well as a history of suicidal ideation and suicide attempts. The treatment of conditions related to NF1 is best managed in centers equipped with doctors experienced in treating patients with NF1. A multidisciplinary management approach is ideal. Preferably, for the management of chronic pain and beyond, the osteopathic holistic approach, targeting the body, mind, and spirit, in combination with other innovative non-pharmacotherapies and pharmacotherapy methods, would be beneficial.

[Spinal deformity in neurofibromatosis type 1]

BACKGROUND

With a prevalence of up to 60%, spinal deformity represents the most common skeletal manifestation of neurofibromatosis type 1. The deformity can occur as a non-dystrophic or as a less common dystrophic type. This distinction is of great relevance because the therapeutic strategy is completely different in each case.

NON-DYSTROPHIC TYPE

The non-dystrophic type can be treated like idiopathic scoliosis due to the comparable behavior of both entities. However, care must be taken regarding the so-called modulation. Modulation describes the formation of dysplasias of the spine. This will result in a progression behavior as known from the dystrophic type.

DYSTROPHIC TYPE

For the dystrophic type, different spinal dysplastic changes are typical. These lead to a rapid progression of deformity and a lack of response to conservative treatment. If untreated, severe and grotesque deformities can arise. This type of deformity requires early surgical intervention, even in childhood. The knowledge about the peculiarities of this disease in general, as well as the typical changes of the spine are prerequisites to managing these often-challenging situations.

[Imaging of tumor predisposition syndromes]

CLINICAL ISSUE

Tumor predisposition syndromes (TPS) are a heterogeneous group of genetic cancers. About 10% of the approximately 2200 malignancies in the childhood in Germany develop due to an inherited disposition, whereby TPS may be underdiagnosed. The focus of this review is set on imaging of Li-Fraumeni syndrome, neurofibromatoses, tuberous sclerosis, overgrowth, and neuroendocrine syndromes.

STANDARD RADIOLOGICAL METHODS

In order to detect tumors at an early stage, screening at specific time intervals for each TPS are required. Ultrasonography and magnetic resonance imaging (MRI), especially whole-body MRI, are particularly important imaging modalities.

METHODOLOGICAL INNOVATIONS

Innovative MRI techniques can increase image quality and patient comfort. MRI acquisition time can be significantly reduced through optimized acceleration factors, motion robust radial sequences and joint acquisition and readout of multiple slices during excitation. Thus, shorter MRI examinations can be performed in younger children without anesthesia.

PRACTICAL RECOMMENDATION

Regular screening with ultrasound and MRI can reduce the morbidity and mortality of the patients affected with TPS.

Unusual Pain Disorders - What Can Be Learned from Them?

Pain is common in many different disorders and leads to a significant reduction in quality of life in the affected patients. Current treatment options are limited and often result in insufficient pain relief, partly due to the incomplete understanding of the underlying pathophysiological mechanisms. The identification of these pathomechanisms is therefore a central object of current research. There are also a number of rare pain diseases, that are generally little known and often undiagnosed, but whose correct diagnosis and examination can help to improve the management of pain disorders in general. In some of these unusual pain disorders like sodium-channelopathies or sensory modulation disorder the underlying pathophysiological mechanisms have only recently been unravelled. These mechanisms might serve as pharmacological targets that may also play a role in subgroups of other, more common pain diseases. In other unusual pain disorders, the identification of pathomechanisms has already led to the development of new drugs. A completely new therapeutic approach, the gene silencing, can even stop progression in hereditary transthyretin amyloidosis and porphyria, ie in pain diseases that would otherwise be rapidly fatal if left untreated. Thus, pain therapists and researchers should be aware of these rare and unusual pain disorders as they offer the unique opportunity to study mechanisms, identify new druggable targets and finally because early diagnosis might save many patient lives.