Rare Presentation in Late Adulthood of a Heterozygous Autosomal Recessive PKD Carrier with Liver and Unilateral Kidney Involvement

Introduction: Autosomal recessive polycystic kidney disease (ARPKD) is a rare genetic disease, predominantly caused by PKHD1 mutations. This ciliopathy of renal tubules and hepatic bile ducts leads to collecting duct malformation, microcyst development, bilateral renal enlargement, and hepatobiliary disease. ARPKD in utero and the perinatal period confers high mortality. Heterozygous carriers of pathogenic PKHD1 variants are not expected to develop ARPKD. However, a subset of ARPKD carriers develop mild cystic kidney and/or liver disease and nephrocalcinosis. We present a heterozygous ARPKD carrier with hepatic and unilateral renal cysts but preserved organ function diagnosed in late adulthood, highlighting ARPKD phenotypic variability. Case Description: A woman with long-standing hypertension and chronic NSAID use presented at age 62 for incidental left renal cysts in 2011, contributing to a size discrepancy between right and left kidneys of 9.8 cm and 15.8 cm, respectively. CT imaging in 2019 showed left kidney cyst stability, but now noted numerous small liver cysts (Figure 1). Genetic testing in 2022 revealed a pathologic heterozygous PKHD1 gene variant (c.107C>T, p.T36M), consistent with ARPKD carrier status. She presently maintains stable kidney and liver function, bland urinalysis, no proteinuria or albuminuria, and radiographic stability (Figure 2). Discussion: Our case contributes to the limited reports of ARPKD manifestations in heterozygous carriers. Unilateral kidney involvement with liver cysts and intact liver function is unusual, possibly representing mosaicism with loss of normal PKHD1 function in the impacted kidney and liver.CT Abdomen and Pelvis (A) coronal and (B) axial views.MRI Abdomen (A) Mixed Bosniak I and II left renal cysts. (B) Numerous small liver cysts.