Renal imaging in 199 Dutch patients with Birt-Hogg-Dubé syndrome: Screening compliance and outcome

Renal Cell Tumor and Cystic Lung Disease: A Genetic Link for Generalists to Be Aware of

Birt-Hogg-Dubé syndrome (BHDS) is a rare autosomal dominant condition characterized by multiple pulmonary cysts, fibrofolliculomas, and renal cell carcinoma. The typical presentations leading to diagnosis include fibrofolliculomas and spontaneous pneumothoraxes. We present a case of a 52-year-old Chinese male who was diagnosed with BHDS after the incidental pickup of an echogenic heterogenous lesion on an abdominal ultrasound done to investigate an abnormal liver function test. The presence of renal cell carcinoma with cystic pulmonary disease should prompt the clinician to consider the diagnosis of BHDS. Knowledge of extrapulmonary findings of common cystic lung diseases may contribute to improved diagnosis of this condition.

Outstanding Characteristics of Birt-Hogg-Dube Syndrome in Korea

Birt-Hogg-Dube (BHD) is a rare genetic disorder characterized by multiple lung cysts, typical skin manifestations, and renal tumors. We prospectively enrolled thirty-one subjects from four South Korean institutions with typical lung cysts, and next-generation sequencing was conducted. We prospectively enrolled thirty-one subjects from four Korean institutions with typical lung cysts. Next-generation sequencing was performed to investigate mutations in the following genes: FLCN, TSC1, TSC2, CFTR, EFEMP2, ELN, FBLN5, LTBP4, and SERPINA1. BHD was diagnosed in 11 of the 31 enrolled subjects (35.5%; FLCN mutations). Notably, we identified three novel mutations (c.1098G>A, c.139G>T, and c.1335del) that have not been previously reported. In addition to FLCN mutations, we also observed mutations in CFTR (16.1%), LTBP4 (9.7%), TSC2 (9.7%), TSC1 (3.2%), ELN (3.2%), and SERPINA1 (3.2%). According to a systematic review of 45 South Korean patients with BHD, the prevalence of pneumothorax (72.7%) was greater in South Korea than in the rest of the world (50.9%; p = 0.003). The prevalence of skin manifestations (13.6%) and renal tumors (9.1%) was lower in Korea than in the rest of the world, at 47.9% [p < 0.001] and 22.5% [p = 0.027], respectively). This study confirmed a significant prediction model for BHD based on age, number of lung cysts (>40), and maximal diameter of lung cysts (>2 cm) regardless of skin manifestations and renal tumors. Importantly, three novel mutations (c.1098G>A, c.139G>T, and c.1335del) were identified. In conclusion, South Korean patients with BHD display characteristics that are different from those observed in patients of other nationalities. Detailed characterization of lung cysts is needed to define BHD, especially in South Korea, even if patients do not present with skin or renal lesions.

The world of rare interstitial lung diseases

The world of rare interstitial lung diseases (ILDs) is diverse and complex. Diagnosis and therapy usually pose challenges. This review describes a selection of rare and ultrarare ILDs including pulmonary alveolar proteinosis, pulmonary alveolar microlithiasis and pleuroparenchymal fibroelastosis. In addition, monogenic ILDs or ILDs in congenital syndromes and various multiple cystic lung diseases will be discussed. All these conditions are part of the scope of the European Reference Network on rare respiratory diseases (ERN-LUNG). Epidemiology, pathogenesis, diagnostics and treatment of each disease are presented.

Characteristic Chest Computed Tomography Findings for Birt-Hogg-Dube Syndrome Indicating Requirement for Genetic Evaluation

Background: Chest computed tomography (CT) findings are important for identifying Birt−Hogg−Dube (BHD) syndrome. However, the predictive power of classical criteria for chest CT findings is weak. Here, we aimed to identify more specific chest CT findings necessitating genetic examination for FLCN gene mutations. Methods: From June 2016 to December 2017, we prospectively enrolled 21 patients with multiple bilateral and basally located lung cysts on chest CT with no other apparent cause, including cases with and without spontaneous primary pneumothorax. All enrolled patients underwent FLCN mutation testing for diagnosis confirmation. Results: BHD was diagnosed in 10 of 21 enrolled patients (47.6%). There were no differences in clinical features between the BHD and non-BHD groups. Maximal cyst diameter was significantly greater in the BHD group (mean ± standard deviation; 4.1 ± 1.1 cm) than in the non-BHD group (1.6 ± 0.9 cm; p < 0.001). Diversity in cyst size was observed in 100.0% of BHD cases and 18.2% of non-BHD cases (p = 0.001). Morphological diversity was observed in 100.0% of BHD cases and 54.6% of non-BHD cases (p = 0.054). Areas under the receiver operating characteristic curves for predicting FLCN gene mutations were 0.955 and 0.909 for maximal cyst diameter and diversity in size, respectively. The optimal cut-off value for maximal diameter FLCN mutations prediction was 2.1 cm (sensitivity: 99%; specificity: 82%). Conclusions: Reliable chest CT features suggesting the need for FLCN gene mutations screening include variations in cyst size and the presence of cysts > 2.1 cm in diameter, predominantly occurring in the bilateral basal lungs.

[DIAGNOSIS OF GENETIC VARIANT CARRIERS IN A PATIENT WITH ASYMPTOMATIC BIRT-HOGG-DUBÉ SYNDROME: A CASE REPORT]

Birt-Hogg-Dubé (BHD) syndrome is an autosomal dominant disorder caused by germline mutations in the folliculin gene (FLCN). It is characterized by skin tumors, multiple lung cysts, and renal tumors. Active genetic testing and appropriate periodic examinations of family lines of patients with BHD syndrome have not been widely performed. In this report, we present our experience regarding the diagnosis of asymptomatic family members with BHD syndrome. The proband was a 65-year-old female with a family history of colorectal cancer and spontaneous pneumothorax that affected her father. Computed tomography revealed an approximately 10 cm-sized tumor protruding from the upper pole of the left kidney, a buried tumor approximately 1.5 cm in length in the right kidney, and multiple pulmonary cysts. The patient underwent laparoscopic radical left nephrectomy. Pathological examination indicated that the resected tumor was a chromophobe renal cell carcinoma. After the surgery, there was no evidence of local recurrence or metastasis. The size of the tumor in the right kidney was monitored, but it did not increase. On FLCN genetic examination, targeted next generation sequencing revealed a partial deletion of exon 14, thus confirming the diagnosis of the patient to be BHD syndrome that caused the previously unreported pathogenic variant. Three years after the surgery, we conducted genetic counseling for the proposita and her three children. Genetic examination, performed at the request of the second daughter, confirmed that she carried the same genetic variant as her mother. This diagnosis prompted the second daughter to begin managing her health via periodic imaging tests.

Combined germline pathogenic variants in FLCN and TP53 are associated with early onset renal cell carcinoma and brain tumors

BACKGROUND

We present a family consisting of a father and his two children with an exceptional phenotype of childhood renal cell carcinoma and brain tumors. Extensive genetic testing revealed two inherited tumor predisposition syndromes in all three family members: Birt-Hogg-Dubé syndrome and Li-Fraumeni syndrome. The corresponding genes (FLCN and TP53) are both located on the short arm of chromosome 17.

METHODS

We describe the phenotype and performed single nucleotide polymorphism (SNP)-based loss of heterozygosity (LOH) analysis of the tumors.

RESULTS

All examined tumors showed somatic loss of the wild-type alleles of both FLCN and TP53.

CONCLUSIONS

We hypothesize that a synergistic effect of both mutations caused the unusual phenotype of childhood renal cell carcinoma in this family. This family emphasizes the importance of further genetic testing if a tumor develops at an unexpected young age in an inherited cancer predisposition syndrome.

Phosphoproteomic analysis of FLCN inactivation highlights differential kinase pathways and regulatory TFEB phosphoserines

In Birt-Hogg-Dubé (BHD) syndrome, germline mutations in the Folliculin (FLCN) gene lead to an increased risk of renal cancer. To address how FLCN affects cellular kinase signaling pathways, we analyzed comprehensive phosphoproteomic profiles of FLCN^POS and FLCN^NEG human renal tubular epithelial cells (RPTEC/TERT1). In total, 15744 phosphorylated peptides were identified from 4329 phosphorylated proteins. INKA analysis revealed that FLCN loss alters the activity of numerous kinases, including tyrosine kinases EGFR, MET and the Ephrin receptor subfamily (EPHA2 and EPHB1), as well their downstream targets MAPK1/3. Validation experiments in the BHD renal tumor cell line UOK257 confirmed that FLCN loss contributes to enhanced MAPK1/3 and downstream RPS6K1/3 signaling. The clinically available MAPK inhibitor Ulixertinib showed enhanced toxicity in FLCN^NEG cells. Interestingly, FLCN inactivation induced the phosphorylation of PIK3CD (Tyr524) without altering the phosphorylation of canonical Akt1/Akt2/mTOR/EIF4EBP1 phosphosites. Also, we identified that FLCN inactivation resulted in dephosphorylation of TFEB Ser109, Ser114 and Ser122, which may be caused by fact that FLCN^NEG cells experience oxidative stress. Together, our study highlights differential phosphorylation of specific kinases and substrates in FLCN^NEG renal cells. This provides insight into BHD-associated renal tumorigenesis and may point to several novel candidates for targeted therapies.

Comment on Balsamo et al.: Birt-Hogg-Dubé syndrome with simultaneous hyperplastic polyposis of the gastrointestinal tract: case report and review of the literature

The publication by Balsamo and colleagues describes a patient with Birt-Hogg-Dubé syndrome and hyperplastic polyposis throughout the gastro-intestinal tract. We question whether the diagnosis of BHD in this patient was justified. Using the previously proposed diagnostic criteria for establishing the diagnosis of BHD as a guideline, we systematically describe our concerns. In our opinion, the patient described by Balsamo and colleagues does not meet any of the proposed major and minor criteria for the diagnosis of Birt-Hogg-Dubé syndrome. Therefore, we believe that it is not justified to suggest a possible association between hyperplastic polyposis and Birt-Hogg-Dubé syndrome based on this patient, even though a higher risk for colorectal polyposis in Birt-Hogg-Dubé syndrome has not been excluded so far.

Renal Neoplasms in Young Adults

Renal cell carcinoma (RCC) is usually diagnosed in older adults (the median age of diagnosis is 64 years). Although less common in patients younger than 45 years, RCCs in young adults differ in clinical manifestation, pathologic diagnosis, and prognosis. RCCs in young adults are typically smaller, are more organ confined, and manifest at lower stages of disease. The proportion of clear cell RCC is lower in young adults, while the prevalence of familial renal neoplastic syndromes is much higher, and genetic testing is routinely recommended. In such syndromic manifestations, benign-appearing renal cysts can harbor malignancy. Radiologists need to be familiar with the differences of RCCs in young adults and apply an altered approach to diagnosis, treatment, and surveillance. For sporadic renal neoplasms, biopsy and active surveillance are less often used in young adults than in older adults. RCCs in young adults are overall associated with better disease-specific survival after surgical treatment, and minimally invasive nephron-sparing treatment options are preferred. However, surveillance schedules, need for biopsy, decision for an initial period of active surveillance, type of surgery (enucleation or wide-margin partial nephrectomy), and utilization of ablative therapy depend on the presence and type of underlying familial renal neoplastic syndrome. In this pictorial review, syndromic, nonsyndromic, and newer RCC entities that are common in young adults are presented. Their associated unique epidemiology, characteristic imaging and pathologic traits, and key aspects of surveillance and management of renal neoplasms in young adults are discussed. The vital role of the informed radiologist in the multidisciplinary management of RCCs in young adults is highlighted. Online supplemental material is available for this article. ^©RSNA, 2022.

Birt-Hogg-Dubé syndrome with rare unclassified renal cell carcinoma: A case report

INTRODUCTION

Birt-Hogg-Dubé syndrome (BHDS) is a rare genetic disease. Renal cell carcinoma is the most serious complication of BHDS. The histological types of BHDS-related renal cell carcinoma are mostly mixed chromophobe/eosinophil and chromophobe cell types. BHDS with unclassified renal cell carcinoma is extremely rare.

PATIENT CONCERNS

A 37-year-old man was admitted to the hospital because of lumbago and hematuria.

DIAGNOSIS

Combined with abdominal enhanced CT and pulmonary CT, BHDS complicated with renal cell carcinoma was diagnosed, and right partial nephrectomy was performed. The postoperative pathological diagnosis was unclassified renal cell carcinoma. Gene detection revealed the FLCN frameshift mutation.

OUTCOMES

No signs of recurrence were observed after regular follow-up.

CONCLUSION

The pathogenesis of BHDS has not been fully elucidated, and the pathological type of BHDS with unclassified renal cell carcinoma is extremely rare. Through case presentation and review of related literature, this paper summarizes the diagnosis and treatment of BHDS complicated with unclassified renal cell carcinoma.

Novel folliculin gene mutations in Polish patients with Birt-Hogg-Dubé syndrome

Background

Birt–Hogg–Dubé syndrome (BHDS) is a rare, autosomal dominant, inherited disease caused by mutations in the folliculin gene (FLCN). The disease is characterised by skin lesions (fibrofolliculomas, trichodiscomas, acrochordons), pulmonary cysts with pneumothoraces and renal tumours. We present the features of Polish patients with BHDS.

Materials and methods

The first case of BHDS in Poland was diagnosed in 2016. Since then, 15 cases from 10 families have been identified. Thirteen patients were confirmed via direct FLCN sequencing, and two according to their characteristic clinical and radiological presentations.

Results

BHDS was diagnosed in 15 cases (13 women and 2 men) from 10 families. The mean ages at the time of first pneumothorax and diagnosis were 38.4 ± 13.9 and 47.7 ± 13 years, respectively. Five patients (33%) were ex-smokers (2.1 ± 1.37 packyears), and 10 (67%) had never smoked cigarettes. Twelve patients (83%) had a history of recurrent symptomatic pneumothorax. Three patients had small, asymptomatic pneumothoraces, which were only detected upon computed tomography examination. All patients had multiple bilateral pulmonary cysts, distributed predominantly in the lower and middle, peripheral, and subpleural regions of the lungs. Generally, patients exhibited preserved lung function. Skin lesions were seen in four patients (27%), one patient had renal angiomyolipoma, and one had bilateral renal cancer. Different mutations of the FLCN gene were identified (mainly in exon 6), with two novel heterozygous variants: c.490delA p.(Arg164GlyTer13) and c.40delC p.(His14ThrsfTer41).

Conclusions

All analysed patients with BHDS presented with lung lesions and with less frequent skin and renal lesions than previously reported in other populations. In addition, more frequent mutations located in exon 6 were detected, and two novel FLCN gene mutations were identified.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-021-01931-0.

Concurrent Birt-Hogg-Dubé Syndrome and Hereditary Paraganglioma-Pheochromocytoma Syndrome Presenting as Metastatic Renal Cell Carcinoma in a 25-Year-Old Man: A Case Report

INTRODUCTION

Birt-Hogg-Dubé syndrome and hereditary paraganglioma-pheochromocytoma syndrome are rare genetic cancer syndromes that predispose patients to renal neoplasia. We report a case of a 25-year-old man with both Birt-Hogg-Dubé syndrome and hereditary paraganglioma-pheochromocytoma syndrome who presented with painless gross hematuria and was found to have metastatic clear cell renal carcinoma.

CASE PRESENTATION

A previously healthy, 25-year-old man presented to his outpatient primary care physician with painless gross hematuria. Urinalysis results demonstrated hemoglobinuria, and serum chemistry results demonstrated a creatinine level of 1.61 mg/dL (baseline of 0.96 mg/dL). A computed tomography scan showed that the patient had a left renal mass, renal vein thrombosis with inferior vena cava extension, and nodal and hepatic metastasis. Biopsy specimens of the left renal mass and liver demonstrated clear cell carcinoma. The patient underwent cytoreductive nephrectomy, caval thrombectomy, and partial colectomy with reanastomosis. He received palliative therapy with 1 mg/kg of ipilimumab and 3 mg/kg of nivolumab for 4 cycles.

CONCLUSION

To our knowledge, this is the first known case report to date documenting a patient with concurrent Birt-Hogg-Dubé syndrome and hereditary paraganglioma-pheochromocytoma syndrome. This case demonstrates the exceptionally young presentation of metastatic renal cell carcinoma with this genotype.

Loss of FLCN-FNIP1/2 induces a non-canonical interferon response in human renal tubular epithelial cells

Germline mutations in the Folliculin (FLCN) tumor suppressor gene cause Birt–Hogg–Dubé (BHD) syndrome, a rare autosomal dominant disorder predisposing carriers to kidney tumors. FLCN is a conserved, essential gene linked to diverse cellular processes but the mechanism by which FLCN prevents kidney cancer remains unknown. Here, we show that disrupting FLCN in human renal tubular epithelial cells (RPTEC/TERT1) activates TFE3, upregulating expression of its E-box targets, including RRAGD and GPNMB, without modifying mTORC1 activity. Surprisingly, the absence of FLCN or its binding partners FNIP1/FNIP2 induces interferon response genes independently of interferon. Mechanistically, FLCN loss promotes STAT2 recruitment to chromatin and slows cellular proliferation. Our integrated analysis identifies STAT1/2 signaling as a novel target of FLCN in renal cells and BHD tumors. STAT1/2 activation appears to counterbalance TFE3-directed hyper-proliferation and may influence immune responses. These findings shed light on unique roles of FLCN in human renal tumorigenesis and pinpoint candidate prognostic biomarkers.

The clinical characteristics of East Asian patients with Birt-Hogg-Dubé syndrome

Background

Birt-Hogg-Dube (BHD) syndrome is an autosomal dominant disease that has been characterized by skin lesions, multiple pulmonary cysts, spontaneous pneumothorax, and renal tumors, but the patients in Asian countries may show fewer symptoms. We aimed to explore and summarize the clinical features of BHD patients in East Asia to facilitate early diagnosis and timely interventions.

Methods

We collected and analyzed the clinical data of patients diagnosed with BHD in our hospital by reviewing medical records. We performed a systematic literature search regarding the presenting clinical features in BHD patients from China, Japan, and Korea and then reviewed the publications that were identified.

Results

In our hospital, 10 patients were diagnosed with BHD from April 2015 to September 2019. After reviewing the literature, we recruited 38 articles, including 12, 20, and 6 reports from China, Japan, and Korea, respectively. A total of 166 patients were included in this study, and 100 of them (60.2%) were females. Multiple pulmonary cysts were present in 145 patients (87.3%), and 124 patients (74.7%) had a history of pneumothorax on at least one occasion. Skin biopsy confirmed fibrofolliculomas (FFs) alone in 22 patients (13.3%), trichodiscomas (TDs) alone in 3 patients (1.8%), and both FFs and TDs in 7 patients (4.2%). Renal carcinoma only occurred in 12 (7.2%) patients. The most frequent genetic mutations in East Asian patients were c.1285delC on exon 11 (18.4%), c.1285dupC on exon 11 (18.4%), and c.1347_1353dupCCACCCT on exon 12 (8.2%).

Conclusions

Our findings suggested that pulmonary cysts are the most frequent radiological findings, and pneumothorax is the most common symptom in East Asian patients with BHD, and that skin lesions and kidney involvement are less frequent. To make an early diagnosis and minimize the severity of complications, careful observation, and timely genetic examination of the FLCN gene is essential.

Birt-Hogg-Dubé syndrome

Birt–Hogg–Dubé syndrome (BHD) is a rare inherited autosomal dominant disorder caused by germline mutations in the tumour suppressor gene FLCN, encoding the protein folliculin. Its clinical expression typically includes multiple pulmonary cysts, recurrent spontaneous pneumothoraces, cutaneous fibrofolliculomas and renal tumours of various histological types. BHD has no sex predilection and tends to manifest in the third or fourth decade of life. Multiple bilateral pulmonary cysts are found on chest computed tomography in >80% of patients and more than half experience one or more episodes of pneumothorax. A family history of pneumothorax is an important clue, which suggests the diagnosis of BHD. Unlike other cystic lung diseases such as lymphangioleiomyomatosis and pulmonary Langerhans cell histiocytosis, BHD does not lead to progressive loss of lung function and chronic respiratory insufficiency. Renal tumours affect about 30% of patients during their lifetime, and can be multiple and recurrent. The diagnosis of BHD is based on a combination of genetic, clinical and/or skin histopathological criteria. Management mainly consists of early pleurodesis in the case of pneumothorax, periodic renal imaging for tumour detection, and diagnostic work-up in search of BHD in relatives of the index patient.

Birt–Hogg–Dubé syndrome is a rare genetic disorder characterised by multiple lung cysts, recurrent pneumothoraces, skin lesions and kidney tumours. As the presenting symptoms may be respiratory, chest physicians should be able to identify this disease.https://bit.ly/2xsOTuk

Cystic lung disease in Birt-Hogg-Dubé syndrome. A case series

Birt-Hogg-Dubé syndrome (BHDS) is a rare autosomal dominant inherited disease caused by mutations in the folliculin (FLCN) gene. It is characterized by lung cysts, skin fibrofolliculomas and an increased risk for the development of renal cancer, especially chromophobe. Lung cysts in the context of BHDS are typically lower lobe predominant, paramediastinal, in relation to the fissures and often elliptical shaped. Skin manifestations can easily go unnoticed. Respiratory physicians need to have a high degree of vigilance as they can be the first to suspect the disease in the setting of diffuse cystic lung disease. Meticulous skin examination and referral to a dermatologist is of utmost importance as it can establish the diagnosis in the least invasive way. Correct diagnosis is crucial as it may allow for genetic counseling to the affected family and the implementation of a monitoring strategy for early detection of renal cancer.