Birt‐Hogg‐Dube Syndrome – an Easily Missed Diagnosis

Birt‐Hogg‐Dube (BHD) syndrome is a rare autosomal genodermatosis characterized by the triad of fibrofolliculomas, trichodyscomas and acrochordons. The gene for BHD was localised to chromosome 17p11.2 and a germline insertion/deletion was identified to cause premature truncation of the BHD protein, folliculin. Patients carry increased risk for developing lung cysts, spontaneous pneumothorax, and renal carcinoma. Prompt diagnosis is important for patient clinical management. We encountered a 41 year‐old white male, otherwise healthy, with classic clinical presentation of BHD, i.e. numerous firm, smooth, whitish papules covering his face and neck, which were developed after adolescence. There is no related family history. Nine biopsies were taken during the past 5 years. The following changes are present: markedly dilated hair follicles, telangiectasia in fibrosing stroma, and melanocytic nevus cells. Diagnoses of epidermal inclusion cyst, fibrous papules, and dermal nevus were given. However, some subtle but diagnostic histopathological features for fibrofolliculoma, perifolliculafibroma, and trichodyscoma were overlooked. Correct diagnosis was reached upon review of all the biopsies. Patient is currently undergoing genetic testing and clinical workups. We present this case to update our knowledge on this rare disease, particularly the diagnostic criteria, differential diagnosis, and diagnostic pitfalls, in order to avoid the delay of correct diagnosis.