Adamantinoma

Clinically, adamantinoma often displays a protracted clinical behavior and gradually enlarges in size. The main complaint is a slow-growing swelling with or without pain. [13] Bone deformity and pathological fracture are other features which lead the patient to seek medical attention. The patient might also present with neurological deficits when the spine is involved. [3]

Plain radiograph:

On x-ray, the tumor is typically well-circumscribed, cortical, multi-lobulated and osteolytic. Intra-lesional opacities, septation, and peripheral sclerosis may also be seen. Multifocality within the same bone is regularly observed. The multifocal radiolucencies which are surrounded by ring-shaped densities produce the characteristic ''soap-bubble'' appearance. [14] The lesion commonly remains intracortical and extends longitudinally, but may also destroy the cortex and invade the medullary cavity or surrounding periosteum and soft tissue. This situation is usually accompanied by a lamellar or solid periosteal reaction.

Computed tomography scan:

Computed tomography scan demonstrates the soft tissue extension and cortical involvement when they exist. However, it does not depict the intraosseous extension of adamantinomas. CT scan plays a role in the routine work-up of adamantinomas and is useful in detecting pulmonary metastases. [3]

Magnetic resonance imaging:

MRI plays a crucial role in locoregional staging since it depicts distant cortical foci, intramedullary and soft tissue extension. MRI is also a useful tool for the determination of tumor-free margins as well as the strategy for reconstructive surgery. [15]

Two morphological patterns of adamantinoma are described on MRI:

• Multiple small nodules in one or more foci
• A solitary lobulated focus

Adamantinomas usually show a low signal intensity on T1-weighted images and a high signal on T2-weighted images. However, these findings are nonspecific. [3][15][3]

The most effective treatment of adamantinoma is wide excision with clear margins [16]. After en block wide resection, reconstruction of the limb can be performed with distraction allografts, osteogenesis,  non-vascularized autogenous bone grafts vascularized autografts and metallic segmental replacement. [7] Amputation for adamantinoma does not improve survival rates compared to limb-preserving surgery [7]. Because of the high rate of recurrence, curettage is not recommended. [5] Radiotherapy and chemotherapy are not effective in the treatment of adamantinoma. [17]

Several authors have pointed to the close relationship between differentiated adamantinoma (osteofibrous dysplasia-like adamantinoma) and osteofibrous dysplasia, which can cause differential diagnostic problems due to similar histological and radiological appearance and typical location in the tibia. [18] Clinically, radiologically and histologically adamantinoma can resemble several bone tumors including bone cysts, giant cell tumor and malignant tumors (chondrosarcoma, angiosarcoma, and metastases). [3]

Adamantinoma is a locally aggressive neoplasm with the potential to metastasize. After inadequate surgery, recurrence of the tumor is frequent.

The risk factors for recurrent or metastatic disease are [19]: 

• Symptoms of less than 5 years duration
• Male sex 
• Young age less than 20 years
• Pain at presentation
• Initial treatment by curettage or resection 
• Lack of squamous differentiation of the tumor
• An increase in the epithelium-to-stroma ratio

Adamantinoma metastasizes in about 15-30% of cases by a hematogenous or lymphatic route to other sites of the body, frequently to the lungs or lymph nodes, less frequently to the bones and abdominal viscera. [3]

According to the literature, the recurrence rate of adamantinoma is as high as 30%-35% [19]. The mortality rate is 6%-18%. [20]

Metastasis to the lung or lymph nodes is as high as 12%-29%. [20]

• Orthopedics
• Oncology
• Surgical oncology

Patients with signs and symptoms of bone pain, soft tissue swelling, or any subjective palpable mass should seek early intervention. 

Adamantinoma is ideally managed by an interprofessional team that consists of orthopedists, radiologists, surgical oncologists, oncologists, and pathologists as well as specialty trained nurses, and pharmacists. Correlation between gross, radiographic, and microscopic features of the lesion is crucial to establish the definitive diagnosis of adamantinoma. Despite its rarity, it is essential to recognize this bone tumor since adequate treatment in early stages result in a better prognosis. Postoperatively, patients require long term follow-up due to the possibility of tumor recurrence and distant metastases. Patients and families require ongoing coordinated education by the clinician and specialty-trained oncology nurse. They should be taught to recognize the signs and symptoms of recurrence or complications. The nurse should assist in coordinating follow-up care and be available for questions. For the best outcomes, a coordination interprofessional open communication approach will lead to the best. [Level V]