HypophosphatasiaJoseph Junewick, MD FACR

05/06/2010

History6 year old female with short stature.

DiagnosisHypophosphatasia

Additional ClinicalAlkaline phosphatase 47 IU/L (normal 100-300 IU/L)

DiscussionHypophosphatasia is related to insufficient tissue-nonspecific alkaline phosphatase which leads to theinability to process phosphate compounds. As a result, cartilage and osteoid mineralization isdeficient. On laboratory evaluation, alkaline phosphatase is low and urinary phospoethanolamine ishigh.Phenotypically, 4 variations of hypophosphatasia are known: perinatal, infantile, childhood and adult.Perinatal and infantile forms are autosomal recessive and often fatal related to respiratoryinsufficiency and myelophhthisic anemia. Childhood and adult forms are autosomal dominant andoften present with extremity pain stiffness and weakness.Perinatal form is characterized by severe lack of mineralization (even more pronounced thanosteogenesis imperfecta). With the infantile form, metaphyseal demineralization predominates with anon-uniform rachitic pattern; localized "chewed out" segments of the metaphyses are a classicfinding. Craniosynostosis is common with prominent convolutional markings and enlarged sellatursica. The adult pattern is similar to osteomalacia with coarsened trabeculae, Looser's zones(although Looser's zones are typically lateral in hypophosphatasia compared to osteomalacia wherethey are usually medial)and insufficiency fractures.

FindingsCR-1) Craniosynostosis with secondary findings of accentuated convolutional markings and enlargedsella tursica, 2) Metaphyseal flaring, irregular periphyseal regions with large "chewed out"metaphyseal lucencies, 3) Osteopenia with thin cortices, and 4) Mildly bowed tibias.MR-Axial T2 images of the orbits show intraosseous invagination of cerebral tissue (related toincreased intracranial pressure and osteomalacia).

ReferenceShore RM. Metabolic Bone Disease. Caffey's Pediatric Diagnositic Imaging. Mosby-Elsivier 11th Ed(2008).ContributorAnne Oostendorp, MD

Sponsored By

DisclaimerThis teaching site is partially funded by an educational grant from GE Healthcare and Advanced Radiology Services, PC. The material on this site isindependently controlled by Advanced Radiology Services, PC, and GE Healthcare and Spectrum Health have no influence over the content of this siteContent Download AgreementThe cases and images on this website are owned by Spectrum Health. Permission is granted (for nonprofit educational purposes) to download and printmaterials to distribute for the purpose of facilitating the education of health professionals. The authors retain all rights to the material and users arerequested to acknowledge the source of the material. Site DisclaimerThis site is developed to reach healthcare professionals and medical students. Nothing this site should be considered medical advice.Only your own doctor can help you make decisions about your medical care. If you have a specific medical question or are seeking medical care, pleasecontact your physician.The information in this website is provided for general medical education purposes only and is not meant to substitute for the independent medicaljudgment of a physician relative to diagnostic and treatment options of a specific medical condition.The viewpoints expressed in these cases are those of the authors. They do not represent an endorsement. In no event will Advanced RadiologyAssociates, PC, Spectrum Health Hospitals (Helen Devos Children's Hospital) or GE Healthcare be liable for any decision made or action taken inreliance upon the information provided through this website.