BHD Summer Case Reports

This summer saw the publication of two new Birt-Hogg-Dubé Syndrome (BHD) case reports. A case report is a published research paper discussing one patient’s story. This is particularly beneficial for rarer conditions such as BHD as clinicians can learn from these cases and potentially reach a diagnosis more easily.

In the first case, a 52-year-old Caucasian man presented to the dermatologist with multiple skin complaints. For several years he had been developing sebaceous cysts which required minor surgery to remove. He also had numerous 0.2-0.4cm white facial bumps on his nose, jaw and forehead; they neither caused him discomfort nor had been previously commented on in his medical records. However, it was these bumps that raised the possibility to the dermatologist that there may be a genetic basis to this condition, and a skin biopsy showing fibrofolliculomas followed by genetic testing confirmed BHD.

Although there was now an answer for the fibrofolliculomas the cause of the recurrent sebaceous cysts was uncertain. Sebaceous cysts are rarely seen in BHD but they can occur, raising the question of whether sebaceous cysts are a less common skin manifestation of BHD. A case study is not able to answer this question because you need several patients to determine whether a symptom is a correlation (occurs at the same time as the syndrome but is not caused by the syndrome) or causation (the syndrome directly causes the symptom). This is why we are very excited to get the BHD registry up and running, where data can be collected from lots of BHD individuals, and we can answer questions such as ‘Are sebaceous cysts a symptom of BHD?’. 

The second case was a 26-year-old Asian woman with a history of recurrent pneumothorax. After the 5^th pneumothorax in 8 months and the discovery that it ran in the family, she was investigated further. A scan showed cystic changes in the lung and examination of the skin showed multiple white-domed bumps on the neck and ears in keeping with fibrofolliculomas. It has been previously noted that the skin manifestations of BHD are less common in the Asian community compared with the Caucasian community and whether it is under-diagnosed or there is a genetic difference is yet to be determined.  Nevertheless, the patient and her family underwent genetic testing which showed a mutation in her FLCN gene inherited from her mother's side. She and her family members were diagnosed with BHD.

Both these cases highlight just how important it is for respiratory physicians and dermatologists to have the tools to recognise and diagnose BHD. In the first case, the patient had no symptoms of BHD except for the fibrofolliculomas and no significant family history. Therefore this diagnosis was dependent on the dermatologists recognising the skin symptoms alone. In the second case, it was the recurrent pneumothorax that led the respiratory physicians questioning why they continued to reoccur and genetic testing.