How is Birt-Hogg-Dubé syndrome diagnosed?

TL;DR: Birt-Hogg-Dubé syndrome is primarily diagnosed through genetic testing that confirms a pathogenic variant in the FLCN gene. Because clinical symptoms like skin papules and lung cysts can be subtle, diagnosis often involves a multidisciplinary evaluation including dermatological, pulmonary, and renal imaging assessments.

How is Birt-Hogg-Dubé syndrome diagnosed in clinical practice?

The diagnostic process for Birt-Hogg-Dubé syndrome typically begins when a physician identifies the clinical triad of skin lesions, pulmonary cysts, or renal tumors. Because the condition is rare and symptoms often manifest at different life stages, the process is rarely straightforward. Diagnosis is confirmed through molecular genetic testing, which identifies a germline mutation in the FLCN gene located on chromosome 17p11.2. If genetic testing is unavailable or inconclusive, clinicians may utilize established clinical diagnostic criteria, which require either one major criterion (e.g., multiple fibrofolliculomas) or multiple minor criteria (e.g., recurrent pneumothorax or renal cell carcinoma).

What tests and examinations are required?

Because Birt-Hogg-Dubé syndrome affects multiple organ systems, a comprehensive diagnostic workup includes several specific evaluations to assess systemic involvement:

• Genetic Testing: Sequencing of the FLCN gene to identify pathogenic variants.


• Dermatological Exam: A skin biopsy of suspected fibrofolliculomas, trichodiscomas, or acrochordons.


• Pulmonary Imaging: High-resolution computed tomography (HRCT) of the chest to identify characteristic bilateral, basal-predominant lung cysts.


• Renal Imaging: Annual abdominal MRI or CT scans to screen for renal cell carcinoma or oncocytomas, which can occur in approximately 15–30% of individuals with Birt-Hogg-Dubé syndrome.

Why is the "diagnostic odyssey" so common for this condition?

Many of the 114 members of the DiseaseMaps community who live with Birt-Hogg-Dubé syndrome have shared experiences of being misdiagnosed or waiting years for an accurate clinical picture. This "diagnostic odyssey" occurs because the skin symptoms are often mistaken for common acne or skin tags, and lung cysts may be attributed to smoking or asthma. It is not uncommon for patients to see a dermatologist, a pulmonologist, and a urologist separately before a single provider connects the systemic nature of the syndrome. If you feel unheard, please know that your frustration is valid; the rarity of Birt-Hogg-Dubé syndrome often means general practitioners lack exposure to the condition.

Which specialists should be involved in the diagnosis?

Given the complexity of Birt-Hogg-Dubé syndrome, diagnosis is most effectively managed by a multidisciplinary team. This team typically includes a clinical geneticist to coordinate testing, a dermatologist to evaluate cutaneous findings, and a urologist or nephrologist to monitor renal health. Because of the risk of spontaneous pneumothorax, a pulmonologist should also be part of the long-term care plan. Seeking out specialists at a major academic medical center or a center of excellence for rare kidney or genetic diseases can significantly reduce the time to an accurate diagnosis.

What conditions are in the differential diagnosis?

Clinicians must distinguish Birt-Hogg-Dubé syndrome from other genetic conditions that present with similar skin or renal manifestations. These include Tuberous Sclerosis Complex, Cowden syndrome, and BAP1 tumor predisposition syndrome. Accurate genetic testing is the only definitive way to differentiate these conditions, ensuring that patients receive the correct surveillance protocol tailored to their specific genetic profile.

Next steps

• Consult with a clinical geneticist to discuss whether FLCN gene testing is appropriate for you or your family members.


• If you have a history of multiple spontaneous pneumothoraces or renal tumors, request a referral to a center specializing in rare genetic tumor syndromes.


• Join the Birt-Hogg-Dubé syndrome community at DiseaseMaps.org to connect with others who have navigated the diagnostic process.


• Keep a detailed medical diary of your skin findings and respiratory history to share with new specialists.

Medical disclaimer: This content is for informational purposes only and does not constitute professional medical advice, diagnosis, or treatment; always seek the advice of your physician or other qualified health provider with any questions regarding a medical condition.

References

• NIH Genetic and Rare Diseases Information Center (GARD): Birt-Hogg-Dube syndrome.


• Orphanet: Birt-Hogg-Dube syndrome (ORPHA:123).


• OMIM (Online Mendelian Inheritance in Man): Folliculin; FLCN (Entry #607273).


• The BHD Foundation: Clinical resources and patient support information.