SPR Unknown #56 -- FINAL

Joanna Rossi, MD

St. Francis Hospital

Andrew K. Poznanski, MD

Children's Memorial Hospital

Abstract

3 y/o male. At birth, parents noticed unusual appearance of chin. Patient was later found to have hypercalcemia and developed failure to thrive.

Keywords

Jansen Type Metaphyseal Chondrodysplasia 1635 SPR unknown 56


Publication Date: 2010-07-22

History

3 y/o male. At birth, parents noticed unusual appearance of chin. Patient was later found to have hypercalcemia and developed failure to thrive.

Findings

In the extremities, the metaphyseal regions are expanded with abnormal widening between the epiphyses and the metaphyses. Within these regions, there are bizarre chondroid calcifications. These findings are most prominent in the proximal humeri, proximal distal femurs, and proximal tibias, but are also noted in the small tubular bones of the hands and feet. Findings of the hyperparathyroid effect are also suggested with subperiosteal bone resorption, which is most evident in the humeri, forearm bones, and small tubular bones.

The skull base is sclerotic, especially in the region of the sphenoid wings. There are extensive postoperative changes in the calvarium from craniosynostosis repair.

Diagnosis

Jansen Type Metaphyseal Chondrodysplasia

DDx

In infancy, Jansen Type Metaphyseal Chondrodysplasia can be mistaken for hyperparathyroidism, rickets, or hypophosphatasia.

Discussion

Jansen type metaphyseal chondrodysplasia is an autosomal dominant disorder that represents the most severe form of metaphyseal chondrodysplasia. This metaphyseal chondrodysplasia is associated with a mutation of the receptor for PTH and PTHrP that causes continuous receptor activation. As a result, even in the absence of PTH or PTHrP, the kidney and bone are affected as though if PTH was increased. The PTH/PTHrP receptor inhibits endochondral ossification, and in infancy results in a large distance between the epiphysis and ossifying osseous shaft. As skeletal maturation occurs, the abnormal cartilage in the widening metaphyseal regions demonstrates dysplastic, abnormal calcification. Bone growth is also stunted, which results in dwarfism.

Age of clinical presentation varies. In the neonatal period it may present with hypercalcemia or other findings which imply severe hyperparathyroidism. Usually, presentation occurs in late infancy. Clinical manifestations may include short stature, waddling gait, lower extremity bowing, contracture deformity of joints, short clubbed fingers, hypertelorism, exophthalmos, nephrocalcinosis, hypercalcemia, hypophosphatemia, and hearing loss.

On radiographs, extremities demonstrate significant expansion of all metaphyseal regions, which are markedly irregular. The hands often reveal wide separation of the metaphyses and epiphyses. Craniofacial findings include pronounced basilar thickening and sclerosis, brachycephaly, platybasia, underdevelopment of paranasal sinuses, prominent supraorbital and zygomatic arches, and hypoplasia of the mandible. The ribs may show irregular expansion anteriorly. Generalized osteopenia, pathologic fracture, or subperiosteal bone formation may also occur. In infancy and childhood, the metaphyses are cupped with a wide zone of abnormal calcification. Long bones demonstrate diffuse radiolucency with abnormal cortical outline. Epiphyses tend to be large and rounded but are otherwise normal. Irregular mineralization of acetabular and glenoid regions, sternal end of clavicles, pubic symphysis, and ischiopubic junction may also be seen. In adult life, notable improvement of metaphyseal bone texture can occur. Bowing of the ulna, radius, tibia, and fibula has also been observed in adults.

References

  1. Charrow J, Poznanski AK. Jansen type of metaphyseal chondrodysplasia: confirmation of dominant inheritance and review of radiographic manifestations in the newborn and adult. Am J Med Genet 1984;18:321-327.
  2. Holthusen W, Holt JF, Stoeckenius M. The skull in metaphyseal chondrodysplasia type jansen. Pediatr Radiol 1975;3:137-144.
  3. Lachman RS. Taybi and Lachman’s Radiology of Syndromes, Metabolic Disorders, and Skeletal Dysplasias. 5th edition. Philadelphia: Mosby, 2007.
  4. Slovis TL. Caffey’s Pediatric Diagnostic Imaging. 11th edition. Philadelphia: Mosby, 2008.

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