Findings: PA and lateral views of the chest demonstrate diffusely increased skeletal radiodensity. In addition, the vertebral endplates are markedly increased in density, which on the lateral film gives the "sandwich" vertebral body appearance.

Diagnosis: Osteopetrosis.

Discussion: Osteopetrosis is the general name for a heterogeneous group of disorders characterized by increased bone mass and increased skeletal radiopacity. The different forms of osteopetrosis are all characterized by failure of osteoclast to resorb bone, with resultant increase in the amount of bone.

Osteopetrosis is generally subdivided into a precocious type (which is usually lethal), and a delayed type which may be relatively asymptomatic. The precocious type presents in infancy with the patient developing cranial nerve dysfunction, anemia, hepatosplenomegaly, and failure to thrive. The anemia is secondary to obliteration of the marrow cavity. Radiographs demonstrate diffuse osteosclerosis with uniformly dense vertebral bodies. Although called the lethal form of osteopetrosis, patients may actually live for a few years. The delayed form of osteopetrosis follows a somewhat more benign course. The disease may manifest itself because of a pathologic fracture, anemia, or cranial nerve dysfunction. The bones are diffusely sclerotic with the delayed form of osteopetrosis. In addition, the cortex is thickened and the vertebral endplate demonstrates markedly increased density giving the characteristic "sandwich" appearance. An unusual form of osteopetrosis is the osteopetrosis with tubular acidosis or alternatively "marble brain", or Slys disease. This rare entity consists of 1) osteopetrosis 2) renal tubular acidosis, and 3) cerebral calcifications. Progressive improvement in the radiographic abnormalities is characteristic of this syndrome.

References:
Kovanlikaya A. Pathogenesis of Osteosclerosis in Autosomal Dominant
Osteopetrosis. AJR. 1997;168:929-932.

Resnick D. Bone and Joint Imaging . W. B. Saunders, Philadelphia.
1996:1139-1141.

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