Patient 1 The first patient had no familial history of VHL disease and was 21 years old when he experienced a sudden right hearing loss. The resulting cophosis was irreversible. The radiological work-up revealed an osteolytic mass of the right temporal bone of heterogeneous signal on both T1- and T2-weighted images (Fig. 1), consistent with the diagnosis of endolymphatic sac tumor. The tumor invaded the otic capsule and the petrous apex but did not extend in the cerebellopontine angle. Its mean tumor diameter (MTD) at diagnosis was approximately 2.6 cm (formula—MTD = (length×width×height)1/3MTD = (length×width×height)1/3 {\hbox{MTD = }}{\left( {{\hbox{length}} \times {\hbox{width}} \times {\hbox{height}}} \right)^{{1/3}}} ) [16]. The rest of the neurological exam was normal and a conservative management was decided. During follow-up, the patient suffered from other manifestations of VHL disease: retinal and central nervous system hemangioblastomas, pheochromocytoma, renal tumors, and pancreatic cysts. The germline mutation of the VHL gene was also identified (c.337C>T, p.Arg113X). After 20 years of radiological surveillance, the size of his endolymphatic sac tumor remains stable (Fig. 2). Apart from his deafness, the patient does not suffer from any vestibular symptoms and his facial function is normal (House and Brackmann grade I).

Patient 1 The first patient had no familial history of VHL disease and was 21 years old when he experienced a sudden right hearing loss. The resulting cophosis was irreversible. The radiological work-up revealed an osteolytic mass of the right temporal bone of heterogeneous signal on both T1- and T2-weighted images (Fig. 1), consistent with the diagnosis of endolymphatic sac tumor. The tumor invaded the otic capsule and the petrous apex but did not extend in the cerebellopontine angle. Its mean tumor diameter (MTD) at diagnosis was approximately 2.6 cm (formula—MTD = (length×width×height)1/3MTD = (length×width×height)1/3 {\hbox{MTD = }}{\left( {{\hbox{length}} \times {\hbox{width}} \times {\hbox{height}}} \right)^{{1/3}}} ) [16]. The rest of the neurological exam was normal and a conservative management was decided. During follow-up, the patient suffered from other manifestations of VHL disease: retinal and central nervous system hemangioblastomas, pheochromocytoma, renal tumors, and pancreatic cysts. The germline mutation of the VHL gene was also identified (c.337C>T, p.Arg113X). After 20 years of radiological surveillance, the size of his endolymphatic sac tumor remains stable (Fig. 2). Apart from his deafness, the patient does not suffer from any vestibular symptoms and his facial function is normal (House and Brackmann grade I).