DISCUSSION
There is no standard treatment for advanced-stage HLRCC-related RCC.
However, most cases are diagnosed in advanced stages with dismal
prognosis.3, 6 It is strongly recommended that the
HLRCC patients’ relatives receive genetic counseling and FH gene
mutation screening. For confirmed HLRCC patients with FH gene
mutation, the RCC surveillance program should start at 8–10 years old
based on the age of the youngest case to date.4 Here,
we report a case of a boy who developed HLRCC-related RCC at 7 years
old, which may affect the starting age of the future RCC-surveillance
program for patients with HLRCC.
A clear association between FH gene mutation and renal cyst
formation has been confirmed in mouse model.7Consistent with the mouse model phenotype, the prevalence of renal cysts
in patients with HLRCC has been reported to be significantly higher than
that in the normal population,8 reaching 45%–50% in
adult cases.3, 9 Although it is controversial that
HLRCC carrier with renal cyst developed kidney cancer more frequently
than without cyst,9 pathological examination of
resected renal cysts of HLRCC patients revealed positive
2-succinyl-cysteine immunostaining,10 suggesting a
complete loss of function of the FH gene in renal cysts of HLRCC
patients because of somatic genetic events. In the present case, the
small solid lesions of RCC were located in the right renal cystic
region. Renal cysts in these HLRCC patients may be precancerous lesions
and should be carefully observed.
The present case was initially misdiagnosed with MCDK because of
multiple renal cysts noted on an enhanced CT scan. Although it is rare,
renal cyst formation can be seen in children with
HLRCC.11 HLRCC should be considered an important
differential diagnosis for children with multiple renal cystic lesions
and many other genetic disorders, including MCDK, Von Hippel–Lindau
syndrome, or tuberous sclerosis.
In conclusion, we present a 7-year-old patient with HLRCC-related RCC
with multiple renal cystic lesions. Since this is the youngest reported
case to date, this report may affect the starting age for future
RCC-surveillance programs for patients with HLRCC.