You are in: eMedicine Specialties > Radiology > MUSCULOSKELETAL AdamantinomaArticle Last Updated: Mar 19, 2008AUTHOR AND EDITOR INFORMATIONSection 1 of 10
  Author: Christopher D Smelser, DO, Staff Physician, Department of Radiology, William Beaumont Army Medical Center Christopher D Smelser is a member of the following medical societies: American Osteopathic Association Coauthor(s): Robert D Stoffey, DO, Director of Women's Imaging, Department of Radiology, Chief of Mammography Section, William Beaumont Army Medical Center; B Wade Mahaney, MD, Staff Physician, Department of Radiology, William Beaumont Army Medical Center; Sean C Keenan, MD, Staff Physician, Department of Radiology, William Beaumont Army Medical Center; Gary E Simmons, MD, Chief, Department of Radiology, William Beaumont Army Medical Center Editors: Michael A Bruno, MD, Associate Professor, Departments of Radiology and Medicine, Pennsylvania State University College of Medicine; Director, Radiology Quality Management Services, Milton S Hershey Medical Center, Pennsylvania State University College of Medicine; Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand; Murali Sundaram, MBBS, FRCR, FACR, Consulting Staff, Department of Diagnostic Radiology, The Cleveland Clinic Foundation; Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute; Felix S Chew, MD, MBA, EdM, Professor, Department of Radiology, Vice Chairman for Radiology Informatics, Section Head of Musculoskeletal Radiology, University of Washington Author and Editor Disclosure Synonyms and related keywords: long bone tumors, classic adamantinomas, differentiated adamantinomas, adamantinomous tumors, primary adamantinomas INTRODUCTIONSection 2 of 10
  BackgroundAdamantinoma is a rare tumor, and its origin remains controversial. Fischer first described the tumor in 1913,7 and since then, only approximately 200 cases have been reported. The tumor occurs almost exclusively in the long bones; tumors in the tibia account for more than 80% of cases. The diaphyseal region is the area most commonly affected. Adamantinomas are classified into 2 distinct types: classic and differentiated. Classic adamantinomas usually occur in patients older than 20 years, whereas differentiated adamantinomas occur almost exclusively in patients younger than 20 years. In addition, the 2 classifications of adamantinomas have distinct radiographic and histologic differences. Patients with adamantinomas present with variable signs and symptoms; most commonly, they report pain and swelling. The tumor is slow growing, and patients may describe discomfort lasting months to years. Although ascertaining accurate mortality statistics is difficult because of the extremely rare nature of this tumor, the 10-year survival rate is believed to be 10%. Treatment options for adamantinoma are surgical and include either marginal or en bloc resection. Unfortunately, neither radiation therapy nor chemotherapy has been proven effective in the treatment of this insidious tumor.1, 2 PathophysiologyAlthough adamantinomas can cause a variety of pathologic and histologic abnormalities, the tumors are usually lobular and well defined. Generally, adamantinomas remain intracortical; however, when prior surgery has been performed or when the tumor is of the classic type, the lesions may extend beyond the periosteum. The histologic features of adamantinomas have a multitude of variations that are present not only among patients but also among different areas of the same tumor. The histologic features of differentiated adamantinomas are predominantly characterized by a pattern of osteofibrous dysplasia. Conversely, in classic adamantinomas, the cells form a tubular, basaloid, squamoid, or spindled pattern. As a result of the variety of manifestations of the tumor, multiple biopsies must often be performed to obtain a representative sample for study. Adamantinomas typically range from 3-15 cm in size, and metastases occur in approximately 15-20% of patients. Metastases generally appear in the lungs and local lymph nodes. Adamantinomas can be found in many other bones in addition to their usual location in the tibia. The humerus, ulna, femur, fibula, and radius are other possible locations in the long bones. Occasionally, the tumor occurs in the spine. Adamantinomas are locally aggressive and extremely slow growing. FrequencyUnited StatesBecause only approximately 200 well-documented cases of adamantinoma have been identified in the almost 100 years since the tumor has been classified, it can be described only as extremely rare. InternationalAdamantinomas are extremely rare. Mortality/MorbidityDespite their slow-growing nature, adamantinomas can cause significant morbidity and mortality. The 10-year survival rate is estimated to be approximately 10%. In addition, painful bowing deformity of the tibia is not an infrequent occurrence in this condition. RaceTo the authors' knowledge, no racial comparative studies have been performed because of the infrequent occurrence of the tumor and because of the difficult and technologically sophisticated diagnosis. Knowing how many cases have been missed in the less developed regions of the world is impossible, just as knowing how many cases remain undiagnosed in industrialized Western nations is difficult. SexAdamantinomas have a male predominance, with an approximate male-to-female ratio of 1.25:1. AgeThe more common classic adamantinoma usually occurs in individuals older than 20 years, whereas the differentiated form of the tumor almost exclusively occurs in those younger than 20 years. However, the tumors have occurred in individuals aged 10-70 years.3 AnatomyThe tibia is by far the most commonly affected bone; tibial tumors account for 80-85% of primary adamantinomas. Other long bones are also commonly affected; occasionally, primary involvement of the spine occurs. Clinical DetailsPatients present with complaints such as a dull ache or bone pain that has been present for months to years. Another common complaint is localized swelling. Often, a history of trauma may be elicited. A palpable mass may be firm or soft; its diameter is usually in the range of 3-15 cm.4 Preferred ExaminationPlain radiography, CT, and MRI may all be used to help assess suspected adamantinomous tumors. However, CT and MRI are not specific in the differentiation of this tumor from other conditions; findings often overlap with those of other tumors and tumor-like lesions. A variety of tumors and tumor-like lesions can mimic an adamantinoma. Histologic examination is key to the identification of an adamantinoma; the histologic features of these tumors have many variations.5, 6 Limitations of TechniquesLimitations of plain-film radiography include the relatively long list of differential diagnoses for adamantinoma. Many pathologic conditions that are as rare as or more common than adamantinoma demonstrate similar characteristics on plain radiographs, as well as CT scans and MRIs. This fact, coupled with the limited experience that most radiologists (and physicians in general) have in dealing with this tumor, makes the diagnosis and treatment of adamantinomas challenging. DIFFERENTIALSSection 3 of 10
Aneurysmal Bone Cyst Chondromyxoid Fibroma Chondrosarcoma Fibrous Dysplasia Other Problems to Be ConsideredEosinophilic granuloma
RADIOGRAPHSection 4 of 10
FindingsIn its early stages, an adamantinoma appears as an elongated linear lucency on plain radiographs, and no periosteal reaction is noted in the surrounding bone. In later stages, cortical sclerosis becomes apparent on plain radiographs [see Image 1]. The most common location is in the diaphyseal region of long bones, especially the tibia. A periosteal reaction and fracture are less common late-term sequelae of adamantinomas that can also be depicted on plain radiographs. The differentiation of adamantinoma from fibrous dysplasia and osteofibrous dysplasia may be difficult by using plain radiographs alone. When questions arise in the diagnosis of the tumor, the histologic and clinical features must be included to narrow the differential diagnosis. Degree of ConfidenceBecause of the extremely rare nature of this tumor, the degree of confidence has not been determined. False Positives/NegativesFalse-positive findings include fibrous dysplasia, osteofibrous dysplasia, fibroma (nonossifying or ossifying), bone cyst (aneurysmal or simple), chondrosarcoma, chondromyxoid fibroma, eosinophilic granuloma, and hemangioendothelioma. Because of the extremely rare nature of this tumor, a list of false-negative findings has not been adequately formulated. CT SCANSection 5 of 10
FindingsCT scans often are used to study adamantinomas, but the findings are not specific. CT scans of the lower extremity often reveal a hypoattenuating sclerotic region in the tibial diaphysis [see Image 2]. Degree of ConfidenceDegrees of confidence have not been accurately determined because of the rarity of this tumor. False Positives/NegativesFalse-positive findings include fibrous dysplasia, osteofibrous dysplasia, fibroma, bone cyst, and chondromyxoid fibroma. MRISection 6 of 10
FindingsMRI often is used to image adamantinomas, but the findings are nonspecific. When MRI is used to study adamantinomas, the tumors demonstrate low signal intensity on T1-weighted spin-echo images and high signal intensity on T2-weighted images. Because these appearances are also typical of most tumors, these findings are nonspecific. Degree of ConfidenceBecause of the rarity of this tumor, the degree of confidence cannot be accurately determined at this time. False Positives/NegativesFalse-positive findings include fibrous dysplasia, osteofibrous dysplasia, fibroma, bone cyst, and chondrosarcoma. NUCLEAR MEDICINESection 7 of 10
FindingsUse of nuclear medicine to study adamantinomas is a relatively new undertaking; therefore, few data regarding the tumors have been collected. However, the following findings are believed to correspond to adamantinomous lesions: increased blood flow in the region of the tumor, increased blood pooling, and increased accumulation of technetium-99m methylene diphosphate in the area of the tumor. INTERVENTIONSection 8 of 10
The only intervention that has been shown to be effective in these tumors is a surgical approach. Neither radiation therapy nor chemotherapy has been proven effective. Treatment options for adamantinoma are surgical and include either marginal or en bloc resection. Marginal resection of the tumor has been shown to be effective in less than one half of the cases studied; however, en bloc resection generally prevents local recurrence of the tumor. MULTIMEDIASection 9 of 10
REFERENCESSection 10 of 10
Article Last Updated: Mar 19, 2008 | |||||||||||||||||||||
