Primary Hyperoxaluria Involving the Liver With Crystal Deposits.

CASE REPORT

A 29-year-old man was known to have multiple bilateral pyelolithotomies for the past 16 years and developed end-stage renal disease 2 years earlier. Molecular genetic testing revealed that he was homozygous for a pathogenic variant of the AGXT gene. Secondary causes of hyperoxaluria were ruled out, given the lack of evidence for malabsorption, high oxalate/low calcium intake in his diet, and lack of prematurity at birth. He was later diagnosed to have hepatitis C virus for the past 6 years, for which no treatment was taken. He was also found to be hepatitis B virus-positive 2 years prior and was on tablet entecavir. His liver function test revealed bilirubin 0.49 g/dL, serum glutamic oxaloacetic transaminase 53 U/L, serum glutamate-pyruvate transaminase 26 U/L, serum alkaline phosphatase 482 U/L, gamma glutamyl transferase 157 U/L, blood urea nitrogen 53 mg/dL, creatinine 7.14 mg/dL, hepatitis B virus DNA 958 IU/mL, and hepatitis C virus antibody 42 IU/mL. He underwent combined liver-kidney transplant for the same. Explant liver showed the presence of birefringent oxalate crystals at several foci within the portal tracts (Figure 1).

Figure 1.

The portal tracts of the liver explants showing (A) oxalate deposits in the portal tracts with hematoxylin and eosin stain (20×) and (B) birefringence noted within oxalate crystals on polarizing microscopy.

Primary hyperoxaluria (PH) is a rare metabolic disorder characterized by inborn errors of glyoxylate metabolism.[1] It has been classified into 3 types. PH type 1 is the most common and is caused by a mutation in the AGXT gene, which leads to a deficiency of the encoded liver-specific peroxisomal enzyme alanine glyoxylate aminotransferase.[2] PH type 2 is caused by a deficiency of glyoxylate reductase/hydroxypyruvate reductase and accounts for about 10% of genetically characterized PH cases. PH type 3 is the rarest type caused by mutation in HOGA1 that encodes the liver-specific mitochondrial enzyme 4-hydroxy-2-oxoglutarate aldolase (HOGA). Each of these mutations leads to overproduction and excretion of oxalate that gets deposited primarily in the kidney. Involvement of liver with oxalate deposits is extremely rare with only 4 cases in the previously reported literature.[1-4] Because the primary enzymatic defect lies in the liver, isolated kidney transplant is not useful in PH and dual organ transplantation is required. In our case, associated comorbidities including chronic hepatitis B and C virus might have precipitated the damage and facilitated crystal deposition.

DISCLOSURES

Author contributions: N. Bansal designed the study, collected and interpreted the data, drafted and critically revised the article, and is the article guarantor. V. Vij designed the study and approved the final version to be published. M. Rastogi designed the study, critically revised the article, and approved the final version to be published.

Financial disclosure: None to report.

Informed consent was obtained for this case report.