Case report

Chronic multifocal non-bacterial osteomyelitis in hypophosphatasia mimicking malignancy

Hermann J Girschick¹ , Etienne Mornet² , Meinrad Beer³ , Monika Warmuth-Metz⁴ and Peter Schneider⁵

¹  Children's Hospital, University of Würzburg, Germany

²  Université de Versailles, Saint Quentin en Yvelines Batiment Fermat Versailles Cedex, France

³  Dept. of Radiology, Section of Pediatric Radiology, University of Würzburg, Germany

⁴  Dept. of Radiology, Section of Neuroradiology, University of Würzburg, Germany

⁵  Clinic for Nuclear Medicine, University of Würzburg, Germany

author email corresponding author email

BMC Pediatrics 2007, 7:3doi:10.1186/1471-2431-7-3

Published:	23 January 2007

Abstract

Background

Hypophosphatasia (HP) is characterized by a genetic defect in the tissue-nonspecific alkaline phosphatase (TNSALP) gene and predominantly an autosomal recessive trait. HP patients suffer from reduced bone mineralization. Biochemically, elevated concentrations of substrates of TNSALP, including pyridoxal-5'-phosphate and inorganic pyrophosphate occur in serum, tissues and urine. The latter has been associated with chronic inflammation and hyperprostaglandinism.

Case presentation

We report on 2 affected children presenting with multifocal inflammatory bone lesions mimicking malignancy: A 6 years old girl with short stature had been treated with human growth hormone since 6 months. Then she started to complain about a painful swelling of her left cheek. MRI suggested a malignant bone lesion. Bone biopsy, however, revealed chronic inflammation. A bone scan showed a second rib lesion. Since biopsy was sterile, the descriptive diagnosis of chronic non-bacterial osteomyelitis (CNO) was established. The diagnostic tests related to growth failure were repeated and subsequent analyses demonstrated a molecular defect in the TNSALP gene. The second girl (10 years old) complained about back pain after she had fallen from her bike. X rays of her spine revealed compressions of 2 thoracic vertebrae. At first these were considered trauma related, however a bone scan did show an additional lesion in the right 4^th rib. A biopsy of this rib revealed a sterile lympho- plasmocytoid osteomyelitis suggesting multifocal CNO. Further analyses did show a decreased TNSALP in leukocytes and elevated pyridoxal phosphate in plasma, suggesting a heterozygous carrier status of HP.

Conclusion

Chronic bone oedema in adult HP and chronic hyper-prostaglandinism in childhood HP do suggest that in some HP patients bone inflammation is present in conjunction with the metabolic defect. Sterile multifocal osteomyelitis could be demonstrated. Non-steroidal anti-inflammatory treatment achieved complete remission. These cases illustrate chronic inflammation of the bone as a new feature of HP.