Actualización en el síndrome Birt-Hogg-Dubé

A case report of Birt-Hogg-Dubé syndrome associated with severe airway obstruction in a 62-year-old female smoker

Birt-Hogg-Dubé syndrome (BHD) typically does not manifest airway obstruction despite the presence of multiple lung cysts. However, the long-term effects of cigarette smoking on lung function among individuals with BHD are unknown. We report a case of a smoking individual diagnosed with BHD syndrome complicated by spontaneous pneumothorax and severe airway obstruction. The patient presented with chronic dyspnea and productive cough. Further work-up revealed severe obstructive airflow limitation, and multiple lung cysts in both lungs, accompanied centrilobular emphysematous changes. Genetic testing confirmed a heterozygous deletion of exons 6-8 in the folliculin gene, confirming the diagnosis of BHD.

Update of penetrance estimates in Birt-Hogg-Dubé syndrome

BACKGROUND

Birt-Hogg-Dubé (BHD) syndrome is a rare genetic syndrome caused by pathogenic or likely pathogenic germline variants in the FLCN gene. Patients with BHD syndrome have an increased risk of fibrofolliculomas, pulmonary cysts, pneumothorax and renal cell carcinoma. There is debate regarding whether colonic polyps should be added to the criteria. Previous risk estimates have mostly been based on small clinical case series.

METHODS

A comprehensive review was conducted to identify studies that had recruited families carrying pathogenic or likely pathogenic variants in FLCN. Pedigree data were requested from these studies and pooled. Segregation analysis was used to estimate the cumulative risk of each manifestation for carriers of FLCN pathogenic variants.

RESULTS

Our final dataset contained 204 families that were informative for at least one manifestation of BHD (67 families informative for skin manifestations, 63 for lung, 88 for renal carcinoma and 29 for polyps). By age 70 years, male carriers of the FLCN variant have an estimated 19% (95% CI 12% to 31%) risk of renal tumours, 87% (95% CI 80% to 92%) of lung involvement and 87% (95% CI 78% to 93%) of skin lesions, while female carriers had an estimated 21% (95% CI 13% to 32%) risk of renal tumours, 82% (95% CI 73% to 88%) of lung involvement and 78% (95% CI 67% to 85%) of skin lesions. The cumulative risk of colonic polyps by age 70 years old was 21% (95% CI 8% to 45%) for male carriers and 32% (95% CI 16% to 53%) for female carriers.

CONCLUSIONS

These updated penetrance estimates, based on a large number of families, are important for the genetic counselling and clinical management of BHD syndrome.

Birt-Hogg-Dubé Syndrome - report of two cases with two new mutations

INTRODUCTION

Birt-Hogg-Dubé syndrome (BHDS) is a rare autosomal dominant genodermatosis characterized by cutaneous fibrofolliculomas and/or trichodiscomas, lung cysts, spontaneous pneumothorax and renal tumors. However, its clinical expression is highly variable. This syndrome is caused by germline mutations in the folliculin gene (FLCN) on chromosome 17p11.2.

MAIN OBSERVATIONS

Two men, 60 and 39-year-old, presented with a several year history of asymptomatic whitish papules scattered over the face and neck. Skin biopsies revealed fibrofolliculomas. The clinical diagnosis of BHDS was corroborated by identification of new heterozygotic mutations in FLCN gene, in exon 6 (C.573_574delinsT) and in exon 9 (c.1015C>T), respectively. Computed tomography scan of the thorax and abdomen showed pulmonary cysts with no suspicious kidneys lesions, and, in the case of the second patient, a mass in left adrenal gland. Laparoscopic left adrenalectomy was performed and histopathological examination was compatible with a malignant perivascular epithelioid cell tumor.

CONCLUSIONS

The presence of multiple fibrofolliculomas should raise the suspicion of BHDS. Patients with this syndrome, regardless of the detected mutation, should be carefully monitored to ensure that potentially serious disease-related conditions can be detected early.

Structured assessment and followup for patients with hereditary kidney tumour syndromes

INTRODUCTION

Optimal clinical assessment and subsequent followup of patients with or suspected of having a hereditary renal cell carcinoma syndrome (hRCC) is not standardized and practice varies widely. We propose protocols to optimize these processes in patients with hRCC to encourage a more uniform approach to management that can then be evaluated.

METHODS

A review of the literature, including existing guidelines, was carried out for the years 1985-2015. Expert consensus was used to define recommendations for initial assessment and followup.

RESULTS

Recommendations for newly diagnosed patients' assessment and optimal ages to initiate followup protocols for von Hippel Lindau disease (VHL), hereditary papillary renal cancer (HPRC), hereditary leiomyomatosis with renal cell carcinoma (HLRCC), Birt-Hogg-Dubé syndrome (BHD), familial paraganglioma-pheochromocytoma syndromes (PGL-PCC), and tuberous sclerosis (TSC) are proposed.

CONCLUSIONS

Our proposed consensus for structured assessment and followup is intended as a roadmap for the care of patients with hRCC to guide healthcare providers. Although the list of syndromes included is not exhaustive, the document serves as a starting point for future updates.

Simultaneous Bilateral Spontaneous Pneumothorax Revealed Birt-Hogg-Dubè Syndrome

Simultaneous bilateral spontaneous pneumothorax is a very rare clinical event, comprising approximately 1% of all spontaneous pneumothoraces. Clinical signs and symptoms may vary from mild chest pain and dyspnea to severe respiratory failure; nevertheless immediate treatment is mandatory as this condition can deteriorate and progress to tension pneumothorax. An underlying lung disease has been commonly described; in most istances primary or secondary tumors, interstitial diseases, and infectious diseases. Birt-Hogg-Dubè syndrome is a rare inherited disorder clinically characterized by multiple fibrofolliculomas, renal tumors, lung cysts, and, in ~24% of the patients, occurrence of spontaneous pneumothorax. In this case, we firstly report the concurrence of these rare conditions, as a patient presenting a simultaneous bilateral spontaneous pneumothorax was diagnosed with Birt-Hogg-Dubè syndrome based on the typical radiological findings and genetic testing of the folliculin gene located on chromosome 17.

Birt-Hogg-Dubé syndrome. State-of-the-art review with emphasis on pulmonary involvement

BACKGROUND

Birt-Hogg-Dubé syndrome (BHDS) is a rare, inherited autosomal-dominant disorder characterized by the development of cutaneous lesions, renal tumors, pulmonary cysts, and spontaneous pneumothorax. The gene responsible for BHDS is located on the short arm of chromosome 17 (17p11.2) and codes for the protein folliculin, which is believed to be an oncogene suppressor protein.

METHODS

We reviewed currently published literature on the main characteristics of BHDS.

RESULTS

Pulmonary cysts and spontaneous pneumothorax are often the presenting manifestations that lead to a final diagnosis in family members affected by the syndrome.

CONCLUSIONS

Certain imaging characteristics of pulmonary cysts, including size and location, can suggest the diagnosis of BHDS based on chest computed tomography alone. The main concern in patients with BHDS is the increased risk of renal carcinoma. The aim of this review is to describe the main pathological, clinical, and imaging aspects of BHDS, ranging from its genetic basis to treatment, with emphasis on pulmonary involvement.