Birt-Hogg-Dubé syndrome (BHDS) is a rare hereditary autosomal dominant condition characterized by benign cutaneous lesions, lung cysts, and increased risk of spontaneous pneumothorax and renal cancer. We report a case of a young Indian boy with bilateral pneumothorax as the first symptom of BHDS. Detailed history examination and investigation showed multiple facial lesions; his computerized tomography was suggestive of renal angiomyolipoma, hepatic angiomyolipoma, pulmonary cyst with pneumothorax, and small bilateral subependymal soft tissue density lesion with calcification in the brain, all of which were collectively suggestive of BHDS. Identification of the above commonly presented clinical features as a syndrome is important for even a primary care physician so as to ensure the timely management and if required referral to a higher center.

The characteristics of the pulmonary cysts on the high-resolution computed tomography (HRCT) chest images are an important diagnostic clue to distinguish among cystic lung diseases. The diagnostic accuracy of HRCT was reported to be as high as 90% by experienced pulmonologists and radiologists. Herein, we report the case of an elderly woman with Birt-Hogg-Dubé syndrome (BHDS) whose HRCT images displayed lymphangioleiomyomatosis-like features of the pulmonary cysts, rendering it difficult for us to diagnose BHDS. This case illustrates the significance of a thorough anamnesis, physical examination, and skin biopsy of facial papules to establish an accurate diganosis.

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.

Birt-Hogg-Dubé syndrome (BHD) is an inherited autosomal dominant condition caused by germline mutations in the FLCN gene, mapped to chromosome 17p11.2. Typical manifestations include pulmonary cysts, spontaneous pneumothorax, fibrofolliculomas, and kidney neoplasms. This report details the case of a 56-year-old female non-smoker diagnosed with multiple pulmonary cysts, presenting with a history of recurrent spontaneous pneumothorax. A computed tomography (CT) scan of her daughter revealed similar pulmonary cysts, raising suspicion of BHD. Further abdominal enhanced CT revealed a left renal tumour and cutaneous fibrofolliculomas on her daughter\'s neck. Consequently, whole-exome sequencing confirmed an FLCN germline mutation in the patient and three relatives, establishing a diagnosis of BHD. This case highlights the importance of familial pulmonary cysts as a clue for diagnosing BHD, providing crucial insights into comparable clinical presentations.

Familial kidney tumors represent a rare variety of hereditary cancer syndromes, although systematic gene sequencing studies revealed that as many as 5% of renal cell carcinomas (RCCs) are associated with germline pathogenic variants (PVs). Most instances of RCC predisposition are attributed to the loss-of-function mutations in tumor suppressor genes, which drive the malignant progression via somatic inactivation of the remaining allele. These syndromes almost always have extrarenal manifestations, for example, von Hippel-Lindau (VHL) disease, fumarate hydratase tumor predisposition syndrome (FHTPS), Birt-Hogg-Dubé (BHD) syndrome, tuberous sclerosis (TS), etc. In contrast to the above conditions, hereditary papillary renal cell carcinoma syndrome (HPRCC) is caused by activating mutations in the MET oncogene and affects only the kidneys. Recent years have been characterized by remarkable progress in the development of targeted therapies for hereditary RCCs. The HIF2aplha inhibitor belzutifan demonstrated high clinical efficacy towards VHL-associated RCCs. mTOR downregulation provides significant benefits to patients with tuberous sclerosis. MET inhibitors hold promise for the treatment of HPRCC. Systematic gene sequencing studies have the potential to identify novel RCC-predisposing genes, especially when applied to yet unstudied populations.

Although very uncommon, severe injury and death can occur during scuba diving. One of the main causes of scuba diving fatalities is pulmonary barotrauma due to significant changes in ambient pressure. Pathology of the lung parenchyma, such as cystic lesions, might increase the risk of pulmonary barotrauma.
Birt-Hogg-Dubé syndrome (BHD), caused by pathogenic variants in the FLCN gene, is characterized by skin fibrofolliculomas, an increased risk of renal cell carcinoma, multiple lung cysts and spontaneous pneumothorax. Given the pulmonary involvement, in some countries patients with BHD are generally recommended to avoid scuba diving, although evidence-based guidelines are lacking. We aim to provide recommendations on scuba diving for patients with BHD, based on a survey of literature on pulmonary cysts and pulmonary barotrauma in scuba diving.
In our opinion, although the absolute risks are likely to be low, caution is warranted. Given the relative paucity of literature and the potential fatal outcome, patients with BHD with a strong desire for scuba diving should be informed of the potential risks in a personal assessment. If available a diving physician should be consulted, and a low radiation dose chest computed tomography (CT)-scan to assess pulmonary lesions could be considered.

Kidney tumors may develop in association with hereditary tumor syndromes. The clinical presentation of these disorders is various, and in some cases, the renal tumor is the first manifestation of the syndrome. Thus, pathologists need to be aware of the gross and histological signs that may suggest the possibility of a tumor syndrome. In this paper, we summarize and illustrate the characteristics of kidney tumors, genetic background along with the extrarenal manifestations in the following diseases: Von Hippel-Lindau syndrome, hereditary papillary renal cell carcinoma syndrome, hereditary leiomyomatosis and renal cell carcinoma syndrome, Birt-Hogg-Dubé syndrome, tuberous sclerosis, hereditary paraganglioma and pheochromocytoma syndrome, and inherited BAP1 tumor syndrome. At the end of the manuscript, we discuss the tumor syndromes with increased risk of Wilms tumors. Such patients require a holistic approach and multidisciplinary care. Our work aims to make those involved in the diagnosis and treatment of kidney tumors aware of these rare diseases that require life-long surveillance. Orv Hetil. 2023; 164(10): 363-375.
A vesedaganatok egy része örökletes tumorszindrómákhoz társultan alakul ki. Ezek klinikai megjelenése változatos, és előfordulhat, hogy a vesedaganat a betegség első manifesztációja, ezért fontos, hogy a patológusok tisztában legyenek azokkal a makroszkópos jelekkel és szöveti elváltozásokkal, amelyek alapján a tumorszindróma lehetősége felvethető. Ebben a közleményben összefoglaljuk és szemléltetjük a kialakuló vesedaganatok jellemzőit, a genetikai hátteret és az extrarenalis eltéréseket a következő kórképekben: Von Hippel–Lindau-szindróma, örökletes papillaris vesesejtes carcinoma szindróma, örökletes leiomyomatosis és vesesejtes carcinoma szindróma, Birt–Hogg–Dubé-szindróma, sclerosis tuberosa, örökletes paraganglioma/phaeochromocytoma szindróma, illetve BAP1-tumorszindróma. A dolgozat végén tárgyaljuk azokat a tumorszindrómákat, amelyekben fokozott a Wilms-tumor kialakulásának kockázata. Az ilyen betegek ellátása holisztikus szemléletet és multidiszciplináris megközelítést igényel, ezért munkánk célja, hogy felhívjuk a vesetumorok ellátásában részt vevő kollégák figyelmét ezekre a ritka, ugyanakkor élethosszig tartó ellátást igénylő betegségekre. Orv Hetil. 2023; 164(10): 363–375.

Birt-Hogg-Dubé syndrome (BHD) is an autosomal dominant disorder caused by germline mutations in the folliculin gene (FLCN) that result in the functional loss of the tumor suppressor folliculin. It is classically associated with cutaneous hamartomas, pulmonary cysts with spontaneous pneumothorax, and various renal cancers. In this case, we present a patient initially diagnosed with chromophobe renal cell carcinoma and subsequently found to have colorectal cancer (CRC). The presence of two separate malignancies in a young patient with a strong family history of CRC (father and paternal grandfather) led to genetic testing, which revealed an FLCN c.1177-5_1177-3del mutation, and a diagnosis of BHD was made. Out of the more than 300 known unique mutations of the FLCN coding region, the c.1285dupC mutation on exon 11 has been the only one convincingly associated with CRC thus far. While larger cohort studies are needed to further clarify this association, we present the first patient with CRC to our knowledge with an FLCN c.1177-5_1177-3del mutation and loss of heterozygosity implicating it as an initiating factor in tumorigenesis. We further explore the studies supporting and refuting the connection between BHD and CRC and highlight the molecular signaling pathways that may play a role in pathogenesis.

BACKGROUND: Birt-Hogg-Dubé (BHD) syndrome is a rare autosomal dominant tumor syndrome caused by Folliculin (FLCN) gene mutation. The clinical manifestations are diverse, and the renal tumor is the most serious.
METHODS: We report the case of a 51-year-old female with multiple space-occupying lesions in both kidneys, as well as bilateral renal cysts and multiple lung cysts. The resected tumors were finally diagnosed as bilateral renal hybrid oncocytic/chromophobe tumor (HOCT) and unilateral chromophobe cell carcinoma. A history of pneumothorax surgery 4 years ago was convinced. All of these strongly suggested the possibility of BHD syndrome. Gene test confirmed a heterozygous germline FLCN nonsense mutation (c.1429C > T, p.Arg477Ter). The patient is still doing well after 20 months of follow-up (cut-off date July 2022).
CONCLUSIONS: This is a case of BHD syndrome presented with bilateral renal tumor, renal cysts, and multiple lung cysts, and confirmed by gene testing. Patients with any combination of one or more of the manifestations should remain alert to the BHD syndrome. Our report will help to deepen the understanding of the clinicopathological features and molecular changes of BHD syndrome.

UNASSIGNED: Birt-Hogg-Dubé syndrome (BHD), also named Hornstein-Knickenberg syndrome, is a rare autosomal dominant disease characterized by lung cysts, recurrent pneumothoraxes, renal cell carcinoma and skin fibrofolliculomas.
UNASSIGNED: This study summarizes the clinical and genetic information of Chinese BHD patients from all available reported cases and explores the relationship between the clinical and genetic spectrum in the hope of improving the prognosis of Chinese BHD patients.
UNASSIGNED: Relative studies were collected by searching PubMed, Cochrane Library, Embase, OVID medicine, SinoMed, Web of Science, China National Knowledge Infrastructure, Wanfang Data and China Hospital Knowledge Database from January 1, 1977 to December 31, 2021. The search strategy included the following term keys: (Birt-Hogg-Dubé syndrome OR Hornstein-Kinckenberg syndrome OR familial pulmonary cysts OR familial spontaneous pneumothorax OR fibrofolliculomas OR trichodiscomas OR inherited renal cancer syndromes OR FLCN) AND (Chinese OR China).
UNASSIGNED: In total, 287 Chinese patients from 143 families described in 31 references were included in this article. Chinese BHD patients tended to present more pulmonary symptoms but fewer skin lesions and renal malignancies, which appeared to be atypical when compared with Caucasian patients. The FLCN mutation spectrum among Chinese BHD patients was established with the mutational hot spot c.1285depC/delC as the most frequent mutation. In addition, this mutation spectrum also showed some differences from other races, with a relatively frequent large deletion c.872-429_1740+1763del (exon 9-14 deletion) reported only in Chinese individuals but no observation of the two mutational hot spots found in Japanese individuals. We also attempted to establish potential pheno-genotype correlations in Chinese BHD patients, but the results were negative.
UNASSIGNED: To improve the prognosis of BHD patients, physicians need to increase their awareness of BHD by focusing on the family history of pneumothorax as well as skin lesions in patients with lung cysts and promptly advising patients on genetic sequencing.