Rare inborn error of metabolism

Etiology: excessive amounts of oxalic acid combine with calcium and deposit throughout body (kidneys, soft tissue, bone)

• hyperoxaluria = urinary excretion of oxalic acid >50 mg/ day
• progressive renal failure
• osteoporosis = cystic rarefaction + sclerotic margins in tubular bones on metaphyseal side, may extend throughout diaphysis
• erosions on concave side of metaphysis near epiphysis (DDx: hyperparathyroidism)
• bone-within-bone appearance of spine
• nephrocalcinosis (2° HPT: subperiosteal resorption, rugger jersey spine, sclerotic metaphyseal bands)

Cx: pathologic fractures