Birt-Hogg-Dubé syndrome: clinical and genetic studies of 10 French families.

BACKGROUND: Birt-Hogg-Dubé syndrome (BHDS) is an autosomal dominant genodermatosis predisposing to the development of multiple fibrofolliculomas (FFs), pulmonary cysts, spontaneous pneumothorax and renal neoplasms. The association of BHDS with various nonrenal neoplasms has been reported but remains controversial.

OBJECTIVES: To report the clinical features and germline mutations in 22 patients from 10 unrelated families with BHDS investigated during a 5-year prospective study by the Department of Dermatology at the University Hospital of Montpellier, France. Also, to define more clearly the characteristics of pulmonary, thyroid, renal and colorectal manifestations associated with BHDS.

METHODS: Twenty-two patients with clinical and histological criteria of BHDS confirmed by FLCN (previously BHD) germline mutation were evaluated. Lung cysts and pneumothorax were detected by thoracic computed tomography (CT) scanning. Abdominal magnetic resonance imaging (MRI) or CT scans and/or renal ultrasonography were performed to screen for tumours. Thyroid nodules and goitres were assessed by clinical examination, ultrasound imaging and measurement of serum thyroid-stimulating hormone and thyrocalcitonin.

RESULTS: Eighteen of the 22 individuals affected by BHDS (82%) were diagnosed with five or more FFs. Multiple epidermal cysts, severe facial hyperseborrhoea and oral papules were noted, respectively, in three of 22 (14%), nine of 22 (41%) and nine of 21 patients (43%). Spontaneous pneumothorax was reported in seven affected patients (32%). Cystic lesions were detected in 14 of 20 patients (70%) and mainly displayed a subpleural and basal location. Renal ultrasound, CT scan and/or MRI revealed renal cysts in 10 patients (45%), without renal carcinoma diagnosed thus far. Thyroid nodules and/or cysts were disclosed by ultrasound examination in 13 of 20 cases (65%). No medullary carcinoma or other thyroid carcinomas were detected. Colonoscopy failed to detect colorectal carcinoma.

CONCLUSIONS: We report here the largest series to date of French patients with BHDS. We noted a high prevalence of thyroid nodules and renal cysts. However, the lack of a control group does not allow assessment of whether or not such association with BHDS is fortuitous.