von Hippel-Lindau (VHL) disease is an inheritable multisystem tumor syndrome 
characterized by multiple benign and malignant tumors affecting multiple organs. 
VHL is the result of a germline mutation in the VHL tumor suppressor gene. 
Molecular genomic analysis routinely confirms the clinical diagnosis. However, 
the use of molecular diagnostic methods can often be insufficient for the 
detection of mosaic germline VHL mutations, making the diagnosis of some cases 
of VHL difficult. Here, we report the case of a VHL mosaic patient with 
bilateral renal lesions in the absence of other VHL-associated lesions. A VHL 
mutation was not originally detected by routine molecular testing. Nonetheless, 
the detection of a heterozygous c.194C>G (p.Ser65Trp) VHL mutation in the 
patient's daughter prompted further genetic assessment and eventually resulted 
in the finding of a mosaic c.194C>G (p.Ser65Trp) VHL mutation in the patient. 
The mutation rate was 18.8 ± 3.84% in peripheral leukocytes. As the frequency of 
VHL mosaicism remains underdetermined, the possibility of a diagnosis of mosaic 
VHL should be considered in patients with both typical and atypical 
VHL-associated manifestations.