Sinonasal mucosal melanoma in The Netherlands between 2001 and 2021: a clinical and epidemiological overview of 320 cases.

PURPOSE: Sinonasal mucosal melanoma (SNMM) is a rare malignancy, characterised by high (local) recurrence rates and poor survival. Comprehensive understanding of tumour etiology is currently lacking, which complicates adequate tumour treatment. Besides examining trends in incidence, this study aims to assess the association between clinical characteristics, treatment practices and patient outcomes, with the objective of establishing a baseline from which SNMM management can be enhanced. METHODS: All newly diagnosed SNMM cases in The Netherlands between 2001 and 2021 were included using data from The Netherlands Cancer Registry (NCR). RESULTS: A total of 320 patients were included. The annual incidence rate for the overall population was stable over the inclusion period with an annual percentage change (APC) of only - 0.01%. The 5-year overall survival (OS) and relative survival (RS) were 24.5 and 32.4%, respectively. Relative survival did not increase over time. The addition of adjuvant radiotherapy to surgery was not associated with a higher OS and RS compared to surgery alone. CONCLUSION: Sinonasal mucosal melanoma is a rare disease with stable incidence rates in the Netherlands between 2001 and 2021. There has been no improvement in survival over the course of the inclusion period. The study reaffirms that adjuvant radiotherapy does not seem to improve patient outcomes. Given the generally poor outcomes for SNMM patients, novel therapeutic options ought to be considered in order to improve care.

Squamous cell carcinoma of the nasal vestibule in the Netherlands: A clinical and epidemiological review of 763 cases (2008-2021).

BACKGROUND: Squamous cell carcinoma of the nasal vestibule (SCCNV) is a rare disease, distinctly different in presentation, treatment, and outcome from squamous cell carcinoma (SCC) of the nasal cavity and paranasal sinuses. However, these are often not analyzed separately. METHODS: The Netherlands Cancer Registry (NCR) and pathology reports from the Dutch Nationwide Pathology Databank (PALGA) were used to identify all newly diagnosed SCCNV cases in the Netherlands between 2008 and 2021. RESULTS: A total of 763 patients were included. The yearly incidence rate displayed a significant downward trend with an annual percentage change (APC) of -3.9%. The 5-year overall survival (OS) and disease-free survival were 69.0% and 77.2%, respectively. The 5-year relative survival was 77.9% and improved slightly over the inclusion period. OS for patients who were staged cT3 appeared to be worse than those staged cT4a, calling the applicability of the TNM-classification into question. CONCLUSION: SCC of the nasal vestibule is rare, with declining incidence rates. Introducing a specific topography code for SCCNV is recommended to enhance registration accuracy. The TNM classification seems poorly applicable to SCCNV, suggesting the need to explore alternative staging methods.

The Additional Value of Somatostatin Receptor Positron Emission Computed Tomography ([68Ga]Ga-DOTATOC PET/CT) Compared with Magnetic Resonance Imaging of the Head and Neck Region in Paraganglioma Patients: A Pilot Study.

The Dutch guideline for patients suspected of head and neck paragangliomas (HNPGLs) recommends magnetic resonance imaging (MRI) and/or computed tomography (CT) of the head and neck area. Additionally, it suggests considering additional nuclear imaging. The aim of this study was to evaluate the outcomes of [68Ga]Ga-DOTATOC PET/CT compared to MRI in patients with suspected HNPGLs and carriers of genetic variations. METHODS: In this single-center pilot study, retrospective data were obtained from consecutive patients between 2016 and 2023. Both MRI and [68Ga]Ga-DOTATOC PET/CT were performed within 12 months. The primary outcome was the location of HNPGLs. RESULTS: A total of 25 consecutive patients were included, and 7 patients (28.0%, p = 0.5) showed differences between the imaging modalities, of whom 5 patients had unexpected localizations with additional uptake by somatostatin receptors (SSTR) on the [68Ga]Ga-DOTATOC PET/CT. CONCLUSIONS: The authors recommend performing baseline imaging with [68Ga]Ga-DOTATOC PET/CT (if available) in variant carriers and using MRI/CT for follow-up according to the regional protocol, thereby shifting the gold standard for baseline imaging from MRI/CT to [68Ga]Ga-DOTATOC PET/CT.

Diagnostic and Treatment-Related Challenges in Sinonasal Teratocarcinosarcoma: A Report of Three Cases.

Background: Sinonasal teratocarcinosarcoma is a rare, aggressive malignancy located almost exclusively in the nasal cavity, paranasal sinuses, or anterior skull base. Histopathological diagnosis can be challenging due to the heterogeneous composition. Methods: Retrospective analysis of 3 patients with sinonasal teratocarcinosarcoma diagnosed and treated at the University Medical Center Utrecht was conducted. Results: Patients presented with nasal obstruction, epistaxis, headaches, or behavioral changes. All three patients had locally advanced disease, and one had lymph node metastases. Two patients underwent surgery followed by radiotherapy, and one underwent neoadjuvant chemotherapy followed by surgery. The follow-up duration ranged from 3 to 32 months. All three patients died due to progression of their disease. Conclusion: Sinonasal teratocarcinosarcoma is characterized by rapid, aggressive local expansion. The prognosis is poor due to a high risk of metastases and locally recurrent disease. Multimodality treatment consisting of surgery, followed by (chemo)-radiotherapy, is essential for optimizing outcomes. Neoadjuvant therapy offers a promising treatment option.

Evaluation of Staging Systems for Cancer of the Nasal Vestibule.

Squamous cell carcinoma of the nasal vestibule is reported to account for less than one percent of all head and neck malignancies. It lacks a designated WHO ICD-O topography code, and multiple systems are available for the staging of this disease, which results in unwanted variability and the subsequent poor reliability of data. The aim of this study was to evaluate the currently available staging systems for cancer of the nasal vestibule, including the recently introduced classification by Bussu et al., which built on Wang's original concept but with clearer anatomical cutoffs. Different staging systems for cancer of the nasal vestibule (UICC nasal cavity, UICC skin cancer of the head and neck, Wang and Bussu et al.) were evaluated via a retrospective analysis of 148 patients. The staging system, per Bussu et al., had the most balanced allocation of patients among the stages. When using the Wang classification as a reference, stage migration occurred less frequently with the Bussu classification. The widespread adoption of a single staging system, as well as the introduction of a designated topography code for cancer of the nasal vestibule, could lead to more uniformity in data reporting and improve an understanding of the incidence and disease outcome. The newly proposed carcinoma of the nasal vestibule classification by Bussu et al. has the potential to improve the staging and allocation among stages. Further analysis of survival data is needed to assess which classification system is best suited for nasal vestibule carcinoma.

Oncological outcome of vocal cord-only radiotherapy for cT1-T2 glottic laryngeal squamous cell carcinoma.

PURPOSE: Early-stage glottic cancer can be treated with radiotherapy only. Modern radiotherapy solutions allow for individualized dose distributions, hypofractionation and sparing of organs at risk. The target volume used to be the entire voice box. This series describe the oncological outcome and toxicity of individualized vocal cord-only hypofractionated radiotherapy for early stage (cT1a-T2 N0). METHODS: Retrospective cohort study with patients treated in a single center between 2014 and 2020. RESULTS: A total of 93 patients were included. Local control rate was 100% for cT1a, 97% for cT1b and 77% for cT2. Risk factor for local recurrence was smoking during radiotherapy. Laryngectomy-free survival was 90% at 5 years. Grade III or higher late toxicity was 3.7%. CONCLUSION: Vocal cord-only hypofractionated radiotherapy appears to be oncologically safe in early-stage glottic cancer. Modern, image-guided radiotherapy led to comparable results as historical series with very limited late toxicity.

Long-term oncological follow-up after mold-based pulsed dose rate brachytherapy for early stage squamous cell carcinoma of the nasal vestibule: A single center experience of 68 patients over a 17-year period.

PURPOSE: Cancer of the nasal vestibule is a rare type of malignancy constituting less than one percent of all head and neck cancers. These tumors are typically diagnosed at an early stage. Both surgery and radiotherapy provide excellent oncological results, but esthetic results are better after radiotherapy. The aim of this study was to evaluate the long-term oncological follow-up after brachytherapy for early stage squamous cell carcinoma of the nasal vestibule. METHODS AND MATERIALS: Retrospective analysis of patients with carcinoma of the nasal vestibule who were treated with primary brachytherapy in the Utrecht University Medical Center. RESULTS: In this single center experience over a 17-year period 68 patients with early stage squamous cell carcinoma of the nasal vestibule were treated with brachytherapy. Two patients had lymph node metastases at first clinical presentation. Median follow-up duration was 46.5 months. Five-year locoregional recurrence-free survival, disease-specific survival, and overall survival were 91.1%, 96.1%, and 66.2%, respectively. All recurrences occurred within the first 3 years of follow-up. CONCLUSIONS: Brachytherapy offers excellent oncological outcomes and is a safe and effective treatment for early stage carcinoma of the nasal vestibule. Recurrences typically occur within 3 years after treatment.

PRAME Staining in Sinonasal Mucosal Melanoma: A Single-Center Experience.

BACKGROUND: Sinonasal mucosal melanoma (MM) is a rare, aggressive melanoma subtype. Complete surgical excision, with or without adjuvant radiotherapy, remains the cornerstone of treatment and yields adequate locoregional control. Metastatic MM is managed similarly to metastatic cutaneous melanoma but with poorer survival. PReferentially expressed Antigen in MElanoma (PRAME) has been identified as a potential diagnostic marker and therapeutic target in the treatment of cutaneous melanoma. METHODS: Retrospective analysis of the clinical characteristics and immunohistochemical features of all sinonasal MM patients referred to the department of Head and Neck Surgical Oncology, UMC Utrecht Cancer Center, between 2011 and 2021 was performed. Single nucleotide polymorphism (SNP) array and next-generation sequencing (NGS) were performed in selected cases. RESULTS: A total of 26 patients with an MM were included. The median follow-up duration was 15 months. At the end of follow-up, 13 patients had died due to progression of their disease, and one patient died of intercurrent disease. PRAME immunohistochemistry was performed in 23 out of 26 cases, all displaying PRAME expression. In two cases PRAME expression was present both within the melanoma cells and in melanocytes in adjacent mucosa. SNP array showed ≥ 5 copy number variants (CNV) in all tested cases, with a median of 29.5 CNVs (IQR 23.25-40). The three most common mutations identified by NGS were NRAS (7 cases) and NF1 (2 cases). CONCLUSION: We show that expression of PRAME is common in sinonasal MM, making PRAME a useful ancillary diagnostic tool and a potential therapeutic target in sinonasal MM. The demonstrated occurrence of extensive presence of PRAME-positive melanocytes in the surrounding mucosa of sinonasal MM might explain the multifocal nature of melanoma in the (sinonasal) mucosa, and would be an extra argument for a PRAME targeting treatment in preventing local disease recurrence.

Validation of the "Rome" Classification for Squamous Cell Carcinoma of the Nasal Vestibule.

Squamous cell carcinoma of the nasal vestibule is considered a rare malignancy that differs from other sinonasal malignancies in many respects. Four staging systems currently exist for this disease, the most recent addition being the "Rome" classification. This study assesses the use of this new classification and its prognostic value regarding various outcome measures. A retrospective multicenter cohort study of patients with a primary squamous cell carcinoma of the nasal vestibule who were treated in three tertiary head and neck oncology referral centers was conducted. A total of 149 patients were included. The median follow-up duration was 27 months. Five-year locoregional control (LRC), disease-specific survival (DSS), and overall survival (OS) were 81.6%, 90.1, and 62.5% respectively. A statistically significant association was observed between the Rome classification and all survival outcomes in both univariable and multivariable analyses. Moreover, it appeared to perform better than the Union for International Cancer Control TNM classification for tumors of the nasal cavity and paranasal sinuses. The new Rome classification can be used effectively and is associated with LRC, DSS, and OS. However, it requires further validation in a larger (prospective) study population.

Application and accuracy of ultrasound-guided resections of tongue cancer.

OBJECTIVES: Surgical removal of squamous cell carcinoma of the tongue (SCCT) with tumour-free margin status (≥5 mm) is essential for loco-regional control. Inadequate margins (<5 mm) often indicate adjuvant treatment, which results in increased morbidity. Ultrasound (US)-guided SCCT resection may be a useful technique to achieve more adequate resection margins compared to conventional surgery. This study evaluates the application and accuracy of this technique. METHODS: Forty patients with SCCT were included in a consecutive US cohort. During surgery, the surgeon aimed for a 10-mm echographic resection margin, while the tumour border and resection plane were captured in one image. Ex-vivo US measurements of the resection specimen determined whether there was a need for an immediate re-resection. The margin status and the administration of adjuvant treatment were compared those of with a consecutive cohort of 96 tongue cancer patients who had undergone conventional surgery. A receiver operating characteristic analysis was done to assess the optimal margin of ex-vivo US measurements to detect histopathologically inadequate margins. RESULTS: In the US cohort, the frequency of free margin status was higher than in the conventional cohort (55% vs. 16%, p < 0.001), and the frequency of positive margins status (<1 mm) was lower (5% vs. 15%, respectively, p < 0.001). Adjuvant radiotherapy was halved (10% vs. 21%), and the need for re-resection was comparable (10% vs. 9%). A cut-off value of 8 mm for ex-vivo measurements prevented histopathologically inadequate margins in 76%. CONCLUSION: US-guided SCCT resections improve margin status and reduce the frequency of adjuvant radiotherapy.

Neuroendocrine neoplasms of the middle ear: Unpredictable tumor behavior and tendency for recurrence.

BACKGROUND: Middle ear adenomatous neuroendocrine tumors (MEANTs) are rare temporal bone tumors. This study evaluates its clinical behavior and therapy outcome. METHOD: Retrospective case review in a tertiary referral center evaluating histopathology, immunohistochemistry, treatment, and outcome. RESULTS: Nine patients were diagnosed with MEANT. One patient presented with locally invasive tumor and underwent extensive en-bloc tumor resection with adjuvant radiotherapy. Seven of eight patients with locally non-aggressive tumor confined to the tympanomastoid space underwent tumor resection. Two patients were disease-free, five presented recurrence, even after apparent successful surgery. All tumors showed neuroendocrine features. Histopathology and immunohistochemistry did not yield prognostic tumor characteristics. CONCLUSION: MEANTs are rare tumors with uncertain biological behavior and subsequent unpredictable clinical course. The preferred treatment is complete surgical tumor resection. They have a high tendency for recurrence, irrespective of negative intermediary surgery. As of yet, there are no prognostic biomarkers, including histopathology and immunohistochemistry.

Time interval between (chemo)radiotherapy and subsequent laryngectomy is not prognostic for post operative complications and survival.

PURPOSE: Pharyngocutaneous fistula (PCF) formation and swallowing difficulties are common and troublesome complications following total laryngectomy (TL). Prior (chemo)radiotherapy ((C)RT) is thought to be a risk factor for these complications, but there is conflicting evidence as to whether the time interval between (C)RT and TL is important. The impact of time interval on these complications and also its impact on overall survival are investigated. METHODS: This is a retrospective case note review of all patients undergoing TL at the University Medical Center, Utrecht, The Netherlands over the 10-year period from January 2008 to December 2017. The cohort was split into those who underwent TL within a year of finishing (C)RT and those longer than 1 year. RESULTS: One hundred and twenty-six patients (108 males, 18 females), with a mean age of 66 underwent total laryngectomy after prior (C)RT in the study period. Overall 5-year survival was 35% with a median follow-up of 30 months. Fifty-four patients underwent laryngectomy within a year of their (C)RT versus 72 patients who had a time interval of more than one year. No differences in PCF rate, risk of dilatation or overall survival could be found between the two groups. CONCLUSIONS: In this modern cohort, time interval between (C)RT and surgery did not impact PCF rate, risk of dilatation or overall survival.

A systematic review on Transoral robotic surgery (TORS) for carcinoma of unknown primary origin: Has tongue base mucosectomy become indispensable?

BACKGROUND: Transoral robotic surgery (TORS) is increasingly used in head and neck surgery and in carcinoma of unknown primary (CUP) origin specifically. Due to the rising incidence of human papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma (OPSCC), there is a rationale for finding ways to de-escalate treatment strategies. This review aims to test the hypothesis that TORS is a meaningful adjunct in the diagnostic (and therapeutic) pathway in CUP in head and neck. METHODS: A structured search of the literature was performed with the search terms 'TORS' and 'Carcinoma of Unknown Primary'. RESULTS: Two hundred and seventy four cases of CUP in which TORS was used were identified for further analysis. Workup for CUP was comparable in all series with regard to physical examination, fine and/or gross needle examination of cervical nodes, fibre optic endoscopy, imaging and robot assisted mucosectomy of the base of tongue (BOT). Identification rate of the primary tumour was 72% on average (range 17%- 90%), and 55%- 96% were HPV positive. Clear margins were achieved in 60% (range 0%-85%) of resected occult tumours. Complication rate of TORS BOT mucosectomy was low with mainly grade I-III sequelae according to Clavien-Dindo. CONCLUSIONS: Transoral robotic surgery seems to be a useful and safe adjunct in the diagnostic and therapeutic pathway in case of CUP in an era of increasing incidence of HPV-positive OPSCC.

Management of Multiple Secreting Paragangliomas in a Succinate Dehydrogenase Subunit D (SDHD) Variant Carrier.

Management of functional intrathoracic sympathetic paragangliomas in succinate dehydrogenase subunit D (SDHD) mutation carriers is challenging, and there is no uniform guideline for treatment to date. The risks of potential malignant behavior and long-term cardiovascular morbidity have to be weighed against the risks of treatment complications. We report the multidisciplinary and shared decision-making approach that resulted in successful surgical removal of 3 paragangliomas in a SDHD mutation carrier.

[A 4-year-old girl with a recurrent infection in the neck: a familiar picture with a rare cause]. / Een 4-jarig meisje met recidiverende halsinfecties.

BACKGROUND: Infections of the neck are frequently seen in young children and are usually harmless and transient. In the case of atypical symptoms, however, it is important to be alert to the possibility of less common causes requiring specific treatment. CASE DESCRIPTION: A 4-year-old girl was seen in the outpatient clinic with a recurrent, inflamed swelling in the neck. The swelling persisted despite repeated incision and drainage. Further investigation with MRI revealed a primary branchial cleft fistula, Work type 2. The epithelialized cartilaginous fistula tract ran from the external auditory canal to the neck, very close to the facial nerve, but could be surgically removed without damage to the nerve. CONCLUSION: In a child with a recurrent swelling or abscess in the neck, with or without a fistula, an extensive differential diagnosis is required including branchial cleft fistula.

Biochemically Silent Sympathetic Paraganglioma, Pheochromocytoma, or Metastatic Disease in SDHD Mutation Carriers.

CONTEXT: Current guidelines do not consistently recommend imaging beyond the head and neck region in succinate dehydrogenase subunit D (SDHD) mutation carriers as long as catecholamine metabolite levels are within the reference range. PARTICIPANTS: We report a series of 10 patients carrying pathogenic variants in the SDHD gene from five tertiary referral centers for paraganglioma (PGL) in the Netherlands, who presented with a sympathetic PGL (sPGL), pheochromocytoma (PHEO), or metastases outside the head and neck region in the absence of excessive catecholamine production. Two of six patients with a biochemically silent sPGL/PHEO developed metastatic disease. Additionally, four patients were found to have metastases outside the head and neck region from head and neck PGL. The average interval between the initial diagnosis and discovery of the silent lesions was 10 (range, 0 to 32) years. CONCLUSIONS: The absence of excessive catecholamine production does not exclude the presence of manifestations of SDHD outside the head and neck region. These findings suggest that a more extensive imaging strategy in SDHD mutation carriers may be warranted for detection of biochemically silent lesions.

Increased Mortality in SDHB but Not in SDHD Pathogenic Variant Carriers.

Germline mutations in succinate dehydrogenase subunit B and D (SDHB and SDHD) are predisposed to hereditary paraganglioma (PGL) and pheochromocytoma (PHEO). The phenotype of pathogenic variants varies according to the causative gene. In this retrospective study, we estimate the mortality of a nationwide cohort of SDHB variant carriers and that of a large cohort of SDHD variant carriers and compare it to the mortality of a matched cohort of the general Dutch population. A total of 192 SDHB variant carriers and 232 SDHD variant carriers were included in this study. The Standard Mortality Ratio (SMR) for SDHB mutation carriers was 1.89, increasing to 2.88 in carriers affected by PGL. For SDHD variant carriers the SMR was 0.93 and 1.06 in affected carriers. Compared to the general population, mortality seems to be increased in SDHB variant carriers, especially in those affected by PGL. In SDHD variant carriers, the mortality is comparable to that of the general Dutch population, even if they are affected by PGL. This insight emphasizes the significance of DNA-testing in all PGL and PHEO patients, since different clinical risks may warrant gene-specific management strategies.

Estimating the penetrance of pathogenic gene variants in families with missing pedigree information.

Accurate assessment of the age-dependent disease risk conferred by germline variants in disease susceptibility genes is often hampered by the way the data are collected. Cohort-based data sets frequently contain an overrepresentation of patients (i.e. carriers of the gene variant of interest affected with the associated disease), and an underrepresentation of disease-free carriers. In order to overcome this problem, penetrance estimates can be based on family-based study designs, through the evaluation of index patients and their family members. This approach facilitates the identification of asymptomatic germline variant carriers. By adjusting for the way these family data are ascertained, an estimate for the penetrance of the pathogenic gene variant can be obtained. However, the family structure is often incomplete or missing. This complicates the estimation of the penetrance, because full adjustment of the likelihood is not possible. We present a conditional likelihood for the estimation of the penetrance of pathogenic gene variants, based on a cohort of multiple families comprising index patients, disease-free and affected non-index carriers, but with missing information on pedigree structure. The proposed estimator corrects for the ascertainment in a robust way and is shown to be more accurate than the frequently used Kaplan-Meier estimator of the penetrance function.

Evaluation of vascular features of vocal cords proposed by the European Laryngological Society.

A newly proposed classification by the European Laryngological Society (ELS) of glottic lesions by narrow-band imaging (NBI) divides their vascular patterns into longitudinal and perpendicular ones. The latter are further subdivided into the wide and narrow patterns. The longitudinal, wide, and narrow patterns are characteristic of benign disease, papilloma, and malignancy, respectively. The aim of the study was to investigate the diagnostic effectiveness of the classification. Forty patients with glottic lesions underwent microlaryngoscopy. The vascular patterns of all vocal cords were defined with NBI. The affected vocal cords were histologically analysed and comprised the arm (A). Unaffected vocal cords were not histologically analysed but followed-up and comprised the arm (B) and were regarded as true negatives if no suspicious changes appeared during the follow-up. The vocal cords from the arm A were categorised into the benign and malignant group according to the histologic result. The ratio of vascular patterns was determined and the groups were statistically compared using the Chi-square test and Fisher's exact test. Perpendicular changes were observed in 36.6% (9/26) of benign diseases and in 100% (23/23) of cancer conditions (p < 0.001). Wide perpendicular changes appeared only in papillomas (6/6) while narrow ones mostly in malignancies (23/26) and also in benign conditions (3/26) (p < 0.001). The sensitivity, specificity, positive and negative predictive values, and accuracy were 100, 95, 88, 100 and 96%, respectively. The new ELS classification can be used effectively and safely to differentiate malignant from benign disease.

The phenotype of SDHB germline mutation carriers: a nationwide study.

OBJECTIVE: Succinate dehydrogenase B subunit (SDHB) gene germline mutations predispose to pheochromocytomas, sympathetic paragangliomas, head and neck paragangliomas and non-paraganglionic tumors (e.g. renal cell carcinoma, gastrointestinal stromal tumor and pituitary neoplasia). The aim of this study was to determine phenotypical characteristics of a large Dutch cohort of SDHB germline mutation carriers and assess differences in clinical phenotypes related to specific SDHB mutations. DESIGN: Retrospective descriptive study. METHODS: Retrospective descriptive study in seven academic centers. RESULTS: We included 194 SDHB mutation carriers consisting 65 (33.5%) index patients and 129 (66.5%) relatives. Mean age was 44.8 ± 16.0 years. Median duration of follow-up was 2.6 years (range: 0-36). Sixty persons (30.9%) carried the exon 3 deletion and 46 (23.7%) the c.423 + 1G > A mutation. Fifty-four mutation carriers (27.8%) had one or multiple head and neck paragangliomas, 4 (2.1%) had a pheochromocytoma and 26 (13.4%) had one or more sympathetic paragangliomas. Fifteen patients (7.7%) developed metastatic paraganglioma and 17 (8.8%) developed non-paraganglionic tumors. At study close, there were 111 (57.2%) unaffected mutation carriers. Statistical analyses showed no significant differences in the number and location of head and neck paragangliomas, sympathetic paragangliomas or pheochromocytomas, nor in the occurrence of metastatic disease or other tumors between carriers of the two founder SDHB mutations (exon 3 deletion vs c.423 + 1G > A). CONCLUSIONS: In this nationwide study of disease-affected and unaffected SDHB mutation carriers, we observed a lower rate of metastatic disease and a relatively high number of head and neck paragangliomas compared with previously reported referral-based cohorts.