Histiocytosis X, Eosinophilic Granuloma

Michael P. D'Alessandro, M.D.
Peer Review Status: Internally Peer Reviewed

Etiology/Pathophysiology:
Etiology unknown. Is a nondisseminated form of histiocytosis with localized proliferation of histiocytes. localized to the skeletal system. Good prognosis.

Pathology:
See an abnormal proliferation of histiocytes throughout the reticuloendothelial system.

Imaging Findings:
Usually monostotic. See a well defined intramedullary defect in tubular and flat bones without sclerosis around it and a circumferential cortical reaction without evidence of cortical destruction or soft tissue mass although if it gets big enough it can have sclerotic periosteal reaction around it. In the spine, it classically presents as vertebral body collapse (platyspondyly).

DDX:
Tumor like lesions of bone producing lytic defects with well defined margins:

• Aneurysmal bone cysts
• Chondroblastoma
• Chondromyxoid fibroma
• Nonossifying fibroma
• Unicameral bone cysts

References:
See References Chapter.

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See related Provider Topics Bone Cancer, Bones, Joints and Muscles or Cancers.

See related Patient Topics Bones, Joints and Muscles or Cancers.

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