Renal histology and MRI findings in a 37-year-old Japanese patient with autosomal recessive polycystic kidney disease .

A 37-year-old Japanese man with a serum creatinine level of 2.5 mg/dL and hepatomegaly was admitted to our hospital for investigation of renal failure. Magnetic resonance imaging (MRI) showed hepatomegaly with small cystic lesions that had high signal intensity on T2-weighted images. There was no splenomegaly, and the kidneys were nearly normal in size with a few small cystic lesions. Renal biopsy revealed that interstitial fibrosis and tubular atrophy affected 60% of the cortex. There was cystic tubular dilation, mainly affecting the distal loop of Henle and distal tubules, since immunohistochemical staining of the dilated tubules was positive for cytokeratin 7 and Tamm-Horsfall protein but was negative for aquaporin 3 and CD10. Immunofluorescence microscopy and electron microscopy did not demonstrate any immune deposits. Genetic analysis identified two different heterozygous missense variants of <italic>PKHD1</italic>, while the patient's asymptomatic parents were each heterozygous for a single <italic>PKHD1</italic> mutation. Accordingly, autosomal recessive polycystic kidney disease (-ARPKD) due to compound heterozygous <italic>PKHD1</italic> mutation was diagnosed. The renal biopsy findings of this patient may be nonspecific, but they were different from the typical renal histology of infantile ARPKD. In conclusion, the renal features of adult-onset ARPKD may differ from those of infantile disease.
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