Cranial manifestations of hypophosphatasia in childhood nephrotic syndrome

A 7-year-old boy was referred to the children's hospital because of gross oedema and tiredness. Massive proteinuria was found and the condition was diagnosed as a childhood nephrotic syndrome. Concomitantly, pathologically low levels of serum alkaline phosphatase were recorded, and this, together with generalized osteoporosis and premature synostosis of cranial sutures, led to a second diagnosis: hypophosphatasia. The patient's family history further confirmed this condition of a heritable defect of metabolism. Dental inspection revealed very carious teeth with characteristically enlarged pulp chambers in molars. Histological examination of an extracted tooth revealed an unusually wide zone of predentine with some other dentinal irregularities. No cement layer was found. The skeletal age and exfoliation of primary teeth, however, were normal, unlike most reported cases of hypophosphatasia. The patient's renal disease was treated mainly with corticosteroids. There is no treatment for hypophosphatasia.