Congenital malformations - Edocr

Chapter 41
Renal Cystic Diseases
PRAVEEN KUMAR
INTRODUCTION
The term renal cystic disease encompasses a
common and heterogeneous group of conditions
that can present in fetal life, childhood, or
later in adult life. Renal cysts in the perinatal period
represent abnormal dilatation of a part of
the renal tubule as a result of hereditary or nonhereditary
developmental disorders, and depending
on the underlying process, either one
or both kidneys can be affected. Renal cysts can
present as the sole manifestation of disease, can
accompany other renal/extrarenal anomalies, or
can be part of a systemic disorder or syndrome.
With the widespread use, better resolution, and
increasing expertise in the use of antenatal and
postnatal ultrasound, these lesions are increasingly
being detected prenatally and in early
neonatal period.
Over the years, many different classifications
have been proposed for renal cystic diseases.
One of the earliest classifications was proposed
by Osathanondh and Potter in 1964 and classified
renal cystic disease of the newborn in the
following four groups: type I included autosomal
recessive polycystic kidney disease (ARPKD);
type II cystic kidneys included dysplastic and
multicystic kidneys and could be unilateral or bilateral;
type III represented autosomal dominant
polycystic kidney disease (ADPKD); and type IV
included cystic kidneys due to an obstruction of
the outflow tract. 1 In 1987, The Committee on
Classification, Nomenclature, and Terminology
of the American Academy of Pediatrics Section
on Urology proposed an expanded classification
to include all causes of renal cystic diseases
(Table 41-1). 2
EPIDEMIOLOGY
ADPKD is one of the most common hereditary
disorders in humans and accounts for 5% of the
end stage renal disease patients in the United
States. 3 It affects 1 in 400 to 1 in 1000 live births
but only a small percentage of all affected patients
present during the perinatal period. The
most common cause of renal cystic disease in a
newborn is multicystic dysplastic kidney (MCDK)
and the incidence of this disorder is reported to
range from 1 in 1000 to 1 in 4500 live births.
The estimated prevalence of ARPKD, a rare type
of renal cystic disease with common perinatal
presentation, is 1 in 20,000 live births with a
heterozygote frequency of 1 in 70. 3,4 Other renal
cystic diseases of the newborn are encountered
only rarely. The overall birth prevalence
of renal cysts in the newborn has been reported
to range from 0.05 to 0.5 per 1000 live births in
population based congenital anomaly birth
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