Birt-Hogg-Dubé syndrome: a case report and a review of the literature

A Novel Mutation as a Rare Cause of Pneumothorax in a Soldier

Birt-Hogg-Dube (BHD) is a rare cause of spontaneous pneumothorax caused by an autosomal-dominant mutation in the folliculin gene (FLCN). The syndrome can have widely variable presentations and is associated with recurrent pneumothorax, cystic lung disease, characteristic skin lesions, and renal tumors. Lung cysts have been described in over 80% of cases, and roughly 24 to 38% of patients have at least one pneumothorax and over 75% have multiple pneumothoraces. One of the defining features of this condition is fibrofolliculomas, which are benign tumors of the hair follicle. Given its rarity, the diagnosis is often missed and/or delayed for many years. This delay has clinical implications as screening for renal cancer is recommended in both the patient and affected family members. Increased recognition of this syndrome can lead to more patients receiving definitive treatment for their first pneumothorax, and being screened for renal cancers. We present a rare case of Birt-Hogg-Dubé with a never before described mutation in the FLCN gene, leading to spontaneous pneumothorax in an active duty male soldier.

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.

[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.

Birt-Hogg-Dubé syndrome: Another mTOR phenomenon

Birt-Hogg-Dubé syndrome is an uncommon autosomal dominant systemic disorder with cutaneous findings notable for fibrofolliculomas or trichodiscomas on the scalp, face, neck, and trunk. These cutaneous signs are associated with bilateral renal cell carcinoma, benign renal cysts, pulmonary cysts, and spontaneous pneumothorax. Given its autosomal dominant inheritance pattern, the successful diagnosis of Birt-Hogg-Dubé syndrome (BHDS) may elucidate a diagnosis in family members. BHDS results from a mutation in the FLCN gene encoding the folliculin protein, a transcriptional regulator of the mammalian target of rapamycin signaling pathway. Like tuberous sclerosis, BHDS's clinical features may subside with the use of oral rapamycin for mammalian target of rapamycin inhibition, a theoretical concept meriting exploration. Although its prevalence in the general population has been estimated at 2 cases per million, BHDS has been detected in a few patients from the nearby Portuguese-lineage quarter of the city of Newark, a disproportionate prevalence possibly explained by the founder effect.

Frequency of truncating FLCN variants and Birt-Hogg-Dubé-associated phenotypes in a health care system population

PURPOSE

Penetrance estimates of Birt-Hogg-Dubé syndrome (BHD)-associated cutaneous, pulmonary, and kidney manifestations are based on clinically ascertained families. In a health care system population, we used a genetics-first approach to estimate the prevalence of pathogenic/likely pathogenic (P/LP) truncating variants in FLCN, which cause BHD, and the penetrance of BHD-related phenotypes.

METHODS

Exomes from 135,990 patient-participants in Geisinger's MyCode cohort were assessed for P/LP truncating FLCN variants. BHD-related phenotypes were evaluated from electronic health records. Association between P/LP FLCN variants and BHD-related phenotypes was assessed using Firth's logistic regression.

RESULTS

P/LP truncating FLCN variants were identified in 35 individuals (1 in 3234 unrelated individuals), 68.6% of whom had BHD-related phenotype(s), including cystic lung disease (65.7%), pneumothoraces (17.1%), cutaneous manifestations (8.6%), and kidney cancer (2.9%). A total of 4 (11.4%) individuals had prior clinical BHD diagnoses.

CONCLUSION

In this health care population, the frequency of P/LP truncating FLCN variants is 60 times higher than the previously reported prevalence. Although most variant-positive individuals had BHD-related phenotypes, a minority were previously clinically diagnosed, likely because cutaneous manifestations, pneumothoraces, and kidney cancer were observed at lower frequencies than in clinical cohorts. Improved clinical recognition of cystic lung disease and education concerning its association with FLCN variants could prompt evaluation for BHD.

A Unique Presentation of Birt-Hogg-Dube Syndrome

Birt-Hogg-Dube (BHD) syndrome is a rare autosomal dominant condition identified by the triad of cutaneous fibrofolliculomas, pulmonary cysts, and renal cell carcinoma. The vast majority of patients with BHD syndrome initially present with spontaneous pneumothorax. This unique case describes a patient with BHD syndrome who presented with sebaceous cysts and perifollicular fibromas. The evaluation by dermatology is what led to his diagnosis. Expanding the clinical presentation of BHD syndrome to encompass a variety of skin findings could help with recognizing these patients before they suffer the serious complications of renal carcinoma and pneumothorax.

A Novel FLCN Intragenic Deletion Identified by NGS in a BHDS Family and Literature Review

Birt–Hogg–Dubé syndrome (BHDS, MIM #135150), caused by germline mutations of FLCN gene, is a rare autosomal dominant inherited disorder characterized by skin fibrofolliculomas, renal cancer, pulmonary cysts and spontaneous pneumothorax. The syndrome is considered to be under-diagnosed due to variable and atypical manifestations. Herein we present a BHDS family. Targeted next generation sequencing (NGS) and multiplex ligation-dependent probe amplification (MLPA) revealed a novel FLCN intragenic deletion spanning exons 10-14 in four members including the proband with pulmonary cysts and spontaneous pneumothorax, one member with suspicious skin lesions and a few pulmonary cysts, as well as two asymptomatic family members. In addition, a linkage analysis further demonstrated one member with pulmonary bullae to be a BHDS-ruled-out case, whose bullae presented more likely as an aspect of paraseptal emphysema. Furthermore, the targeted NGS and MLPA data including our previous and present findings were reviewed and analyzed to compare the advantages and disadvantages of the two methods, and a brief review of the relevant literature is included. Considering the capability of the targeted NGS method to detect large intragenic deletions as well as determining deletion junctions, and the occasional false positives of MLPA, we highly recommend targeted NGS to be used for clinical molecular diagnosis in suspected BHDS patients.

Clinical, Histopathological, and Management Challenges of Multiple Familial Trichoepithelioma: A Case Report of a Patient Presenting with Multiple Facial Papules

Trichoepitheliomas (TE) are benign skin tumours of the pilosebaceous apocrine unit with follicular differentiation. Multiple familial trichoepithelioma (MFT) is a considerably rare condition inherited in an autosomal dominant pattern. We present a case of a 15-year-old male who presented with multiple papulo-nodular lesions in the central face and a family history of a similar type of lesions from his mother. Significance of consideration of various clinical differential diagnoses with serious pathological outcomes, strategies followed in the diagnosis including histopathological evaluation aided by immunohistochemical investigations, and subsequent challenges that may be faced in the management of MFT in light of the presentation with multiple facial papules are documented in this case report.

A Case of Birt-Hogg-Dubé Syndrome and Multiple Intracranial Aneurysms

Birt-Hogg-Dubé (BHD) syndrome is a rare autosomal dominant condition that is associated with fibrofolliculomas, pulmonary cysts, renal cysts, and renal cancer. There have been few reports in the literature of intracranial vascular pathology in patients with BHD syndrome, and intracranial vascular pathology is currently not a part of the diagnostic criteria. Given the rarity of this disease, there has not been enough evidence for a definitive link between BHD syndrome and intracranial vascular abnormalities. We present a case of a patient with BHD syndrome and multiple cerebral aneurysms.

Hereditary Leiomyomatosis and Renal Cell Cancer

Hereditary leiomyomatosis and renal cell cancer is a genodermatosis with an autosomal dominant inheritance pattern. It is a tumour predisposition syndrome characterized by cutaneous and uterine leiomyomas, and increased susceptibility to develop renal cell carcinoma. There are 200-300 families with hereditary leiomyomatosis and renal cell carcinoma reported worldwide, but the syndrome is believed to be underdiagnosed. Cutaneous leiomyomas are small smooth muscle tumours that tend to grow over time. Larger lesions, in particular, can cause pain or itching. Uterine leiomyomas have a high penetrance in women with hereditary leiomyomatosis and renal cell cancer. They frequently cause symptoms, and surgical intervention is often necessary. Hereditary leiomyomatosis and renal cell cancer-associated renal cell carcinomas have a high potential to metastasize. Patients are diagnosed by genetic testing if a pathogenic mutation is demonstrated in the gene encoding fumarate hydratase. Immunohistochemistry may be a useful diagnostic approach in patients without a detectable pathogenic mutation. Diagnosed patients should be monitored for renal tumours in a lifelong surveillance programme.

Birt-Hogg-Dubé syndrome presenting with spontaneous pneumothorax and extensive pulmonary cysts in the absence of skin lesions or renal pathology

Birt-Hogg-Dubé (BHD) syndrome is an autosomal dominant condition which classically manifests with skin lesions such as fibrofolliculomas, pulmonary cysts that predispose to spontaneous pneumothorax and an increased risk of developing renal cell carcinoma. We describe the case of a patient who presented with a spontaneous pneumothorax on a background of multiple lung cysts, in the absence of cutaneous fibrofolliculomas and renal tumours. A germline mutation in the folliculin FLCN gene was subsequently identified, confirming BHD syndrome. Our case highlights the importance of considering a broad differential diagnosis for the cause of a spontaneous pneumothorax in the presence of unexplained cystic lung disease and emphasises the value of maintaining a high index of clinical suspicion for inherited causes of pneumothoraces.

Prosthetic Aortic Valve Endocarditis in a Patient With Birt-Hogg-Dube Syndrome due to Lactobacillus paracasei

Various causative organisms and predisposing factors were implicated in the pathogenic process behind prosthetic valve endocarditis. Lactobacillus paracasei, a classic constituent of probiotics, rarely causes infections in humans and was reported only in few case reports. The use of probiotics was hypothesized to be a risk factor for these infections; however, no causative relationship could be drawn. We describe a 75-year-old woman with history of Birt-Hogg-Dube syndrome and bioprosthetic aortic valve replacement who presented with worsening dyspnea was found to have Lactobacillus paracasei bacteremia and evidence of bacterial vegetations noted on transesophageal echocardiography (TEE) along with evidence of severe aortic insufficiency. Based on antibiotics sensitivity profile, she was treated with penicillin and gentamycin, which resulted in bacterial clearance on repeat blood cultures, and the patient was transferred to a different facility to undergo replacement of the prosthetic aortic valve. Although Lactobacillus paracasei is rarely involved in human infections, it should be suspected in patients with underlying structural heart/valvular disease, recent antibiotic exposure or recent probiotic use who are presenting with evidence of infective endocarditis. Combination antibiotics including beta lactams, aminoglycosides and clindamycin are suggested treatment of choice for this organism.

Role of Radiologists in the Diagnosis of Unsuspected Birt-Hogg-Dubé Syndrome in a Tertiary Clinical Practice

OBJECTIVE. Birt-Hogg-Dubé (BHD) syndrome is considered rare. Growing evidence indicates that it is underdiagnosed. The purpose of this study is to ascertain the impact of radiology reports that suggest the possibility of BHD syndrome on downstream management and a final diagnosis of BHD syndrome. MATERIALS AND METHODS. In this retrospective study, electronic medical records were searched to identify radiology reports suggesting the possibility of BHD syndrome in patients without a known or suspected diagnosis. Clinical and demographic information, the specialty of the ordering clinician, and imaging findings and confidence conveyed in the radiology report (with BHD syndrome listed as the most likely diagnosis versus one among several possibilities but not as the leading diagnosis) were recorded. The resultant downstream evaluations that were captured included referral for genetic evaluation and subsequent diagnosis of BHD. RESULTS. Between 2004 and 2016, radiologists suggested a diagnosis of BHD syndrome in 87 patients. Of these patients, 15% (13/87) underwent genetic evaluation, and 54% of those patients (7/13) had positive findings. Genetic evaluation was more likely for patients with a history of pneumothorax (p = 0.004) or involvement of the lungs and kidneys (p = 0.003). The urology department referred the highest percentage of patients (31% [4/13]) for genetic evaluation. CONCLUSION. Radiologists have a unique opportunity to suggest BHD syndrome, allowing appropriate genetic testing, screening, and counseling of patients and their families. Clinical presentation, including a history of pneumothorax and involvement of both the lungs and kidneys on imaging, may determine which patients are ultimately referred for genetic evaluation. We hope that increasing awareness that BHD syndrome is not so rare may lead to early diagnosis.

Childhood pneumothorax in Birt-Hogg-Dubé syndrome: A cohort study and review of the literature

Background

Birt‐Hogg‐Dubé syndrome (BHD) is an autosomal dominantly inherited cancer predisposition syndrome associated with an increased risk of spontaneous pneumothorax (SP) and renal cell carcinoma in the adult population. Recent studies suggest that BHD accounts for up to 10% of all SP in adults and BHD in children with SP have been reported.

Methods

To explore to what extent BHD is the cause of childhood pneumothorax, we studied a Danish BHD cohort consisting of 109 cases from 22 families. Clinical data was gathered by review of medical records. A systematic literature search concerning childhood and adolescence pneumothorax in BHD was performed and identified publications reviewed.

Results

In our cohort, three of 109 BHD cases experienced childhood pneumothorax, corresponding to a prevalence of 3%. Reviewing the literature, data regarding more than 800 BHD cases were covered. Only seven previously published cases of childhood pneumothorax in BHD were identified.

Conclusion

Our findings suggest that BHD is likely the cause of a larger subset of childhood pneumothoraces than hitherto recognized. Awareness of BHD as a cause of childhood pneumothorax needs to be raised to provide patients and relatives with the possibility of specialized management of SP and regular renal cancer surveillance.

Recurrent renal cancer in Birt-Hogg-Dubé syndrome: A case report

INTRODUCTION

Birt-Hogg-Dubé syndrome (BHDS) is a rare autosomal dominant disease. It is caused by constitutional mutations in the FLCN gene. Since BHDS is a rare syndrome therefore it is unknown to many physicians. However, it is important to identify this rare syndrome at early stages because incidence of renal cancer in BHD patients is very high and its detection at early stages can prevent its metastasis. Hence, we want to present a case of BHDS and draw the attention of the treating physician to this rare inherited disorder and discuss its appropriate diagnosis and management.

CASE PRESENTATION

We present a case of a 50-year old male presented to the consulting clinics of a University Hospital with right flank pain since the last 2 months. The Computed Tomography (CT) and biopsy on the right renal mass indicated clear cell type renal cell carcinoma with significant lymphadenopathy. Past history of cystic lung disease and pneumothorax along with positive finding of renal cell carcinoma on CT and biopsy suggested Birt-Hogg-Dub́e (BHD) syndrome. The patient underwent right radical nephrectomy and lymph node dissection. His 3 months post- surgery follow up CT scan indicated disease recurrence.

CONCLUSION

In conclusion, it is important to identify this rare syndrome at early stages. Diagnosis for the patients with a positive family history for renal cell cancer and pneumothorax should be considered. FLCN sequencing should also be taken into account in patients and their families because incidence of renal cancer in BHD patients is very high and detection at early stages can prevent its metastasis.