Adamantinoma
Synonyms and keywords:

# Overview
- Adamantinoma was first discovered by Fischer in 1913. Adamantinoma is classified into 2 distinct types: classic and differentiated (Osteofibrous dysplasia (OFD) - like). Adamantinoma is a low grade, malignant bone tumor. This tumor is predominantly located in tibia ( most in mid-portion of tibia). Most locations of the tumor include tibia, ipsilateral fibula, humerus, ulna, femur, fibula. It is a Yellow gray or grayish white tumor. In microscopic examination admixture of both epithelial and osteofibrous component can be seen. Adamantinoma may be caused by displacement of basal epithelium of skin during embryogenesis, traumatic implantation. Adamantinoma is a rare bone cancer ( 0.10.5% of all primary bone tumors ). Risk factors in the development of adamantinoma may include benign osteofibrous dysplasia. If left untreated, 15-30% of patients with adamantinoma may metastasize to other parts of the body such as lungs or nearby lymph nodes. The diagnosis of adamantinoma is based on the findings of radiologic studies such as x-ray, CT, and MRI. The most common symptoms of adamantinoma include swelling with or without pain. Less common symptoms of adamantinoma include pathological fracture. Adamantinoma may present with bowing deformity of the tibia. There is no medical therapy for adamantinoma. Radiation therapy and chemotherapy are not effective. Surgery is the mainstay of treatment for adamantinoma.

# Historical Perspective
Adamantinoma was first discovered by Fischer in 1913.

# Classification
Adamantinoma is classified into 2 distinct types: classic and differentiated (Osteofibrous dysplasia (OFD) - like)

# Pathophysiology
Adamantinoma is a low grade, malignant bone tumor. This tumor is predominatly located in tibia ( most in mid-portion of tibia).  It is a biphasic tumor including epithelial and osteofibrous components..
Most locations of the tumor include:
- Tibia ( 80 to 85 percent of cases)
- Ipsilateral fibula (10 to15% of cases)
- Humerus
- Ulna
- Femur
- Fibula
- Radius
- Ribs
- Spine
- Small bones of the hand and foot
- Yellow gray or grayish white tumor
- Fleshy or firm in consistency
- Some OFD like adamantinomas are solid
- Macroscopic cysts containing blood like fluid, occasionally
- Admixture of both epithelial and osteofibrous component, most commonly solid nests of basaloid cells in classic adamantinoma
- Nuclear atypia in a few cases
- Several patterns of growth including
Tubular
Basaloid
Squamous
Spindle-cell
Osteofibrous dysplasia-like variant
- Tubular
- Basaloid
- Squamous
- Spindle-cell
- Osteofibrous dysplasia-like variant
- A few cases from a large series have exhibited nuclear atypia
- Foci of calcification, giant cells 
- Foci of xanthoma and spindle cells
- Positives for keratins 14 and 19

# Causes
Adamantinoma may be caused by: 
- Displacement of basal epithelium of skin during embrogenesis
- Traumatic implantation
- Synovial origin

# Differentiating Adamantinoma from Other Diseases
Adamantinoma must be differentiated from aneurrysmal bone cyst, unicameral bone cyst, fibrous dysplasia,  chondromyxoid fibroma, eosinophilic granuloma, giant cell tumor, chondromyxoid fibroma, osteomyelitis, chondrosarcoma, epithelial metastasis, hemangioendothelioma, nonossifying fibromas, angiosarcoma.

# Epidemiology and Demographics
Adamantinoma is a rare bone cnacer ( 0.10.5% of all primary bone tumors ).
The prevalence of Adamantinoma is approximately 0.11 per 100000 individuals in Europe.
The incidence of Adamantinoma was estimated to be less than 300 cases worldwide.
Patients of all age groups may develop adamantinoma. The median age at diagnosis is  25 to 35  years.
Men are more commonly affected by adamantinoma than women. The men to women ratio is approximately 5 to 4.

# Risk Factors
Risk factors in the development of adamantinoma may include benign osteofibrous dysplasia. It maybe a precursor of adamantinoma.

# Screening
There is insufficient evidence to recommend routine screening for adamantinoma.

# Natural History, Complications, and Prognosis
If left untreated, 15-30% of patients with adamantinoma may metastasize to other parts of the body such as lungs or nearby lymph nodes. . Adamantinoma has mortality rate of 13%to 18%. 
Complications of adamantinoma include metastases to the lungs.
Prognosis is generally good. Male patint, short duration of symtoms, young age ( less than 20 years) and lack of squamous differentiantion of tumor are related with unfavorable clinical outcome. 

# Diagnosis

## Diagnostic Study of Choice
The diagnosis of adamantinoma is based on the findings of radiologic studies such as x-ray, CT, and MRI.

## History and Symptoms
The initial symptoms of adamantinoma are often nonspecific. The most common symptoms of  adamantinoma include swelling with or without pain. Less common symptoms of adamantinoma include pathological fracture( 23% of patients)  and neurological symptoms in spinal lesions.

## Physical Examination
Adamantinoma may present with bowing deformity of the tibia.
Spinal lesions may be manifested by neurologic symptoms in addition to pain.

## Laboratory Findings
Paraneoplastic hypercalcemia can be seen in tibial adamantinoma and pulmonary metastasis

## Electrocardiogram
There are no ECG findings associated with adamantinoma.

## X-ray
An x-ray may be helpful in the diagnosis of adamantinoma. Findings on an x-ray suggestive of adamantinoma include central or eccentric, multilocular lesion in tibia. The tumor is found in the diaphyseal location. Metaphyseal extention or only involvement of metaphysis is seen occationally. The lesions are well circumscribed surrounded ring-shaped densities ( soap -bubble appearance). The lesion are more intra-cortical, but if they destroy cortex, extracortical soft tisuue invasion can be seen. The periosteal reaction can be minimal to prominnet.

## Echocardiography or Ultrasound
There are no echocardiography/ultrasound  findings associated with adamantinoma.

## CT scan
CT scan may be helpful in the diagnosis of adamantinoma. Findings on CT scan suggestive of adamantinoma include cortical involvement and the soft tissue extension if it exist.
Chest CT scan can detect pulmonary metastasis. 

## MRI
MRI is helpful in the diagnosis of adamantinoma. It is useful in detection distant cortical foci, soft tissue, and intramedullary extension. MRI is a very important diagnostic study for stating of tumor and tumor-free margins. Findings on MRI suggestive of adamantinoma include a solitary lobulated focus or multiple small nodules in one or more foci. Tumors demonstrate low signal intensity on T1-weighted images and high signal on T2-weighted images.

## Other Imaging Findings
Bone scan may be helpful in the diagnosis of adamantinoma. Findings on a nuclear medicine suggestive of  adamantioma include:
- Increased blood flow in the region of the tumor
- Increased accumulation of technetium-99m methylene diphosphate in the area of the tumor

## Other Diagnostic Studies
There are no other diagnostic studies associated with adamantinoma.

# Treatment

## Medical Therapy
There is no medical therapy for adamantinoma. Radition therapy and chemotherapy are not effective. 

## Surgery
Surgery is the mainstay of treatment for adamantinoma.
- Tumor resection with wide operative margins and then limb reconstruction 
- Amputation

## Primary Prevention
There are no established measures for the primary prevention of adamantinoma.

## Secondary Prevention
There are no established measures for the secondary prevention of adamantinoma.