Differential Diagnosis of Autosomal Dominant Polycystic Kidney Disease

ABSTRACT

Autosomal dominant polycystic kidney disease (ADPKD) is the most common life-threatening hereditary disorder characterized by cyst formation and enlargement in the kidney and other organs. There are two known mutations in ADPKD: PKD1 (85% of cases), whose clinical manifestations are the earliest and most rapidly evolving; and PKD2 (15% of cases). PKD1 is a large and complex gene encoding polycystin-1, whereas PKD2 is smaller and encodes polycystin-2. There are a few patients reported in the literature who will not fit into any of these subgroups, leading clinicians to question the exact diagnosis, for example, patients without either of these mutations or patients with predominant development of hepatic cysts. The differential diagnosis between ADPKD and other cystic kidney diseases depends on the age of the patient, family history and the presence of associated manifestations. In adult patients in the absence of a family history of ADPKD, doctors should exclude: multiple benign simple cysts; localised or acquired renal cystic disease; medullary sponge kidney; bilateral parapelvic cysts; autosomal recessive polycystic kidney disease (ARPKD); tuberous sclerosis complex (TSC); von Hippel-Lindau disease; autosomal dominant medullary cystic disease; autosomal dominant polycystic liver disease; and X-linked dominant orofaciodigital syndrome type I. In young children, in the absence of family history of ADPKD, it is important to distinguish from ARPKD, contiguous PKD1-TSC2 syndrome or Meckel-Gruber syndrome. This chapter will review the challenges in the diagnosis of multiple kidney cysts in adults, pointing out the most important signs which doctors should be aware of to reach an appropriate diagnosis in this condition.