Definition
adamantinoma of long bones,a rare tumor of limb bones,
usually the tibia, that microscopically resembles an ameloblastoma;
the histogenesis is uncertain.
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Radiographic Appearance
Adamantinoma appears as an
eccentric, well-circumscribed, and lytic lesion on plain x-ray. The
lesion usually has several lytic defects separated by sclerotic bone
which gives a "soap-bubble" appearance. There is cortical thinning
but little periosteal reaction. The lesion may break through the
cortex and extend into soft tissue. MRI helps demonstrate the
intraosseus and extraosseous involvement. The differential diagnosis
radiologically includes osteofibrous dysplasia, fibrous dysplasia,
ABC, chondromyxoid fibroma and chondrosarcoma .
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Pathology
Adamantinoma of the long
bones, or extragnathic adamantinoma, is an extremely rare, low-grade
malignant tumor of epithelial origin. It is not related to
adamantinoma or ameloblastoma of the mandible and maxilla which is
derived from Rathke's pouch. Adamantinoma is a locally aggressive
osteolytic tumor that is found 90% of the time in the diaphysis of
the tibia with the remaining lesions found in the fibula and long
tubular bones. The tumor usually occurs in the second to fifth
decade of life but may affect patients from ages 3 to 73. In 20% of
cases there are metastases late in the course of the disease.There
is often a history of trauma associated with adamantinoma but its
role in the development of this lesion remains unclear. The patient
usually has swelling that may be painful. The duration of symptoms
can vary from a few weeks to years.
Treatment
Adamantinoma is treated by wide
surgical excision. This tumor is insensitive to radiation and may
metastasize to lungs, lymph nodes and abdominal organs by both
hematogenous and lymphatic routes. Chemotherapy is not used.
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