Genetically diagnosed Birt–Hogg–Dubé syndrome and familial cerebral cavernous malformations in the same individual: a case report

When faced with an unusual clinical feature in a patient with a Mendelian disorder, the clinician may entertain the possibilities of either the feature representing a novel manifestation of that disorder or the co-existence of a different inherited condition. Here we describe an individual with a submandibular oncocytoma, pulmonary bullae and renal cysts as well as multiple cerebral cavernous malformations and haemangiomas. Genetic investigations revealed constitutional mutations in FLCN, associated with Birt–Hogg–Dubé syndrome (BHD) and CCM2, associated with familial cerebral cavernous malformation. Intracranial vascular pathologies (but not cerebral cavernous malformation) have recently been described in a number of individuals with BHD (Kapoor et al. in Fam Cancer 14:595–597, 10.1007/s10689-015-9807-y, 2015) but it is not yet clear whether they represent a genuine part of that conditions’ phenotypic spectrum. We suggest that in such instances of potentially novel clinical features, more extensive genetic testing to consider co-existing conditions should be considered where available. The increased use of next generation sequencing applications in diagnostic settings is likely to lead more cases such as this being revealed.