Author(s)

Ek. Tavernaraki, M. Pantziara, M. Stassinopoulou, E. Andriotis, A.Tavernaraki

Patient

male, 23 year(s)

The patient presented with local pain, swelling , tenderness of the thigh, and loose teeth. There were not any systemic signs or symptoms.

The patient presented with local pain, swelling , tenderness of the thigh, and loose teeth. There were not any systemic signs or symptoms.

Plain radiographs of the skull showed large lesions, giving the appearance of "geographic skull" and "floating teeth". Radiographs of the femur and pelvis showed multiple lytic lesions with ill-defined borders, including one lesion of the acetabulum.

Computer tomography of the pelvis and femur showed lytic leasions with disruption of the cortex and small soft tissue mass.

MRI of the hips and femur showed isotense lesions on T1-weighted images, which showed enhacement with gadolinium, and high signal areas of bone replacement on T2-weighted images.

Hand-Schuller-Christian disease is a chronic disseminated form of histiocytosis X, in which idiopathic non-neoplastic proliferation of histiocytes occurs. It may involve any bone, but preferred sites are the skull, mandible, spine and long bones. The lesions may be well defined or poorly defined with or without associated sclerotic borders. A variable amount of periosteal reaction can be present, ranging from a thick solid type to lamellated.

In the skull, lesions usually have sharply defined borders with uneven involvement of the inner and outer table. At the centre of the lytic process a button sequestrum may appear. Large lesions give the appearance of "geographic skull". In the mandible and maxilla, bone destruction may produce the appearance of "floating teeth".

In the spine, typically, there is lysis of affected vertebrae leading to progressive collapse (vertebra plana) with preservation of adjacent disc space, which usually allows distinction from infection.

In the long bones, lesions usually arise in the diaphysis or metaphysis and are centred in the medullary cavity causing endosteal scalloping and eventually cortical penetration. The lesions may also appear as permeative lesions with ill-defined borders and periosteal reaction. Bone scintigraphy is of limited usefulness. CT may be useful to define the extent of the process. On MRI examination, T1-weighted images reveal a lesion isointense to adjacent tissue and T2-weighted images reveal high signal areas of marrow replacement.

The differential diagnosis includes:

• Skull lesions: osteomyelitis, epidermoid cyst.
• Long bones (aggressive form): round cell lesions, Ewing's sarcoma, osteosarcoma, leukaemia, acute osteomyelitis.
• Long bones (less aggressive form): simple cysts, fibrous dysplasia, chronic osteomyelitis.
• Vertebra plana: leukaemia, metastatic neuroblastoma, idiopathic osteonecrosis.

Finally, the disease may involve the liver, spleen, lymph nodes, skin, and lungs. The classic triad is exophthalmos, diabetes insipidus and skull lesions.