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Adamantinoma is a rare low-grade malignant bone tumor of uncertain histogenesis which occurs commonly in the diaphyses and metaphyses of the tibia. The term adamantinoma has been given to this tumor due to its histological resemblance to ameloblastoma of the jaws[1]. Its histopathology shows biphasic patterns of epithelial cells and osteofibrous components. There are two types of adamantinoma: the classical and the differentiated type, which resembles osteofibrous dysplasia[2]. Despite advances in imaging techniques, the definitive diagnosis of adamantinoma is mainly established by histopathological examination.


The origin of adamantinoma is unknown. The most popular theory is that of displacement of basal epithelial cells of the skin during embryological development. [3] This theory is supported by the fact that the anterior tibia where the enchondral formed bone is closest to the skin surface, is predominantly involved by adamantinoma. Based on immunohistochemical and ultrastructural studies, there is a suggestion that adamantinoma may be of epithelial origin. [3] The possible relationship between adamantinoma and osteofibrous dysplasia is still a matter of debate. The potential link between these two lesions has implications for the diagnosis, prognosis, and treatment. [4][3] 


Adamantinoma is a rare tumor accounting for approximately 0.4% of all primary malignant bone tumors. There is a slight male predominance with a sex-ratio of 5:4. Adamantinomas frequently occur in young to middle-aged adults (20 to 40 years of age) but rarely affect elderly individuals and children. The most common sites involved by adamantinoma are the anterior metaphysis or diaphysis of the tibia. Other sites include the fibula, ulna, femur, humerus, and radius. [5][2]



A recurrent pattern of numerical abnormalities featuring extra copies of chromosomes 7, 8, 12, 19 and 21 have been detected in classic as well as osteofibrous dysplasia-like forms of adamantinoma. [6][7]


Macroscopic findings:

Classic adamantinoma usually presents as a cortical, well-demarcated, yellowish-grey, lobulated tumor of a firm to bony consistency with peripheral sclerosis. It may be a single lesion or occasionally multifocal. Macroscopically detectable cystic spaces are commonly filled with straw-colored or blood-like fluid.

Histological findings:

Classical adamantinomas are characterized by easily recognizable epithelial and osteofibrous components that may be mixed in various proportions and differentiation patterns. The four main differentiating patterns of classic adamantinoma are:

  • Basaloid
  • Tubular
  • Spindle cell
  • Squamous

The first two patterns are most commonly encountered, but all patterns may be present. The spindle-cell component is more often observed in recurrences, lining cystic spaces, and in metastases. The osteofibrous component is composed of storiform-oriented spindle cells. Woven bone trabeculae are usually present in, or next to the center of the lesion prominently rimmed by osteoblasts, and with varying amounts of transformation to a lamellar bone at the periphery of the tumor. Foam cells or myxoid change may be present, and mast cells or multinucleated giant cells are occasionally detected. Mitotic activity is usually low. A fifth histological pattern, the so-called osteofibrous dysplasia-like variant, is characterized by a predominance of osteofibrous tissue, in which small groups of epithelial cells are only encountered by careful search or immunohistochemistry. 

Extensive sampling of adamantinoma is significant especially in the differentiated form where the epithelial component is only focally encountered.

Immunohistochemical study:

The fibrous tissue is positive for vimentin. The epithelial cells show coexpression of keratin, EMA, vimentin, p63, and podoplanin. [8][9] Estrogen, progesterone, and N-cadherins are found in classic, but not in osteofibrous dysplasia-like adamantinoma. [10] In classic adamantinomas, the epithelial component is surrounded by a continuous basement membrane consisting of collagen IV, laminin and galectin 3 [10], whereas less distinct epithelial islands show multiple interruptions or no surrounding basement membrane at all. EGF/EGFR expression is restricted to the epithelial component. FGF2/FGFR1 is present in both parts [11], while in culture, the cells express M-CSF and RANKL, which may contribute to the osteolysis observed. [12]

History and Physical

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. [15][3]

Treatment / Management

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]

Differential Diagnosis

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. [20][16][3]


According to the literature, the recurrence rate of adamantinoma is as high as 30%-35% [21]. The mortality rate is 6%-18%. [22]

Metastasis to the lung or lymph nodes is as high as 12%-29%. [22]


  • Orthopedics
  • Oncology
  • Surgical oncology

Deterrence and Patient Education

Patients with signs of bone pain, swelling of bones or joints, any palpable mass found on the bones, should seek early intervention. 

Enhancing Healthcare Team Outcomes

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]

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Adamantinoma - Questions

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A 33-year-old male presented with a swelling of the right upper leg for the past 3 months. X-ray of the right leg showed a well-defined radiolucent lesion involving the diaphysis of the tibia with cortical sclerosis. En bloc excision of the lesion was done, and the specimen was sent for laboratory diagnosis. Gross examination showed a hard bony mass measuring 5x4x3 cm size. Cut surface revealed a firm, homogeneous whitish mass filling and expanding the medullary cavity. Microscopy showed extensive areas of a fibrous stroma with cell nests. Cells were oval to spindle with peripheral palisading, and focal areas of squamous differentiation with definite intercellular bridges were seen. Atypia or mitotic activity was not present. Epithelial cells showed cytokeratin positivity, and stromal cells showed positivity for vimentin and smooth muscle actin. What is the most likely diagnosis?

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A 34-year-old male patient presented with swelling of the left leg that was gradually increasing for the last two years. The x-ray of the leg showed a diaphyseal cortical erosion image associated with densification of the soft tissue. Computed tomography scan revealed a tumor process with the involvement of the medullary cavity. The histological examination of the biopsy specimen was consistent with the diagnosis of adamantinoma. Which of the following will be the treatment of choice of this tumor?

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Adamantinoma - References


Puchner SE,Varga R,Hobusch GM,Kasparek M,Panotopoulos J,Lang S,Windhager R,Funovics PT, Long-term outcome following treatment of Adamantinoma and Osteofibrous dysplasia of long bones. Orthopaedics     [PubMed]
Jundt G,Remberger K,Roessner A,Schulz A,Bohndorf K, Adamantinoma of long bones. A histopathological and immunohistochemical study of 23 cases. Pathology, research and practice. 1995 Mar;     [PubMed]
Qureshi AA,Shott S,Mallin BA,Gitelis S, Current trends in the management of adamantinoma of long bones. An international study. The Journal of bone and joint surgery. American volume. 2000 Aug;     [PubMed]
Szendroi M,Antal I,Arató G, Adamantinoma of long bones: a long-term follow-up study of 11 cases. Pathology oncology research : POR. 2009 Jun;     [PubMed]
Yoshida S,Murakami T,Suzuki K,Itou S,Watanuki M,Hosaka M,Hagiwara Y, Adamantinoma Arising in the Distal End of the Fibula. Rare tumors. 2017 Mar 24;     [PubMed]
Keeney GL,Unni KK,Beabout JW,Pritchard DJ, Adamantinoma of long bones. A clinicopathologic study of 85 cases. Cancer. 1989 Aug 1;     [PubMed]
Khémiri C,Mrabet D,Mizouni H,Abbes I,Mnif E,Sellami S,Essaddem H, Adamantinoma of the tibia and fibula with pulmonary metastasis: an unusual presentation. BMJ case reports. 2011 Oct 16;     [PubMed]
Houdek MT,Sherman CE,Inwards CY,Wenger DE,Rose PS,Sim FH, Adamantinoma of bone: Long-term follow-up of 46 consecutive patients. Journal of surgical oncology. 2018 Dec;     [PubMed]
Jain D,Jain VK,Vasishta RK,Ranjan P,Kumar Y, Adamantinoma: a clinicopathological review and update. Diagnostic pathology. 2008 Feb 15;     [PubMed]
Dickson BC,Gortzak Y,Bell RS,Ferguson PC,Howarth DJ,Wunder JS,Kandel RA, p63 expression in adamantinoma. Virchows Archiv : an international journal of pathology. 2011 Jul;     [PubMed]
Kashima TG,Dongre A,Flanagan AM,Hogendoorn PC,Taylor R,Athanasou NA, Podoplanin expression in adamantinoma of long bones and osteofibrous dysplasia. Virchows Archiv : an international journal of pathology. 2011 Jul;     [PubMed]
Camp MD,Tompkins RK,Spanier SS,Bridge JA,Bush CH, Best cases from the AFIP: Adamantinoma of the tibia and fibula with cytogenetic analysis. Radiographics : a review publication of the Radiological Society of North America, Inc. 2008 Jul-Aug;     [PubMed]
Kanamori M,Antonescu CR,Scott M,Bridge RS Jr,Neff JR,Spanier SS,Scarborough MT,Vergara G,Rosenthal HG,Bridge JA, Extra copies of chromosomes 7, 8, 12, 19, and 21 are recurrent in adamantinoma. The Journal of molecular diagnostics : JMD. 2001 Feb;     [PubMed]
Van der Woude HJ,Hazelbag HM,Bloem JL,Taminiau AH,Hogendoorn PC, MRI of adamantinoma of long bones in correlation with histopathology. AJR. American journal of roentgenology. 2004 Dec;     [PubMed]
Springfield DS,Rosenberg AE,Mankin HJ,Mindell ER, Relationship between osteofibrous dysplasia and adamantinoma. Clinical orthopaedics and related research. 1994 Dec;     [PubMed]
Van Rijn R,Bras J,Schaap G,van den Berg H,Maas M, Adamantinoma in childhood: report of six cases and review of the literature. Pediatric radiology. 2006 Oct;     [PubMed]
Moon NF,Mori H, Adamantinoma of the appendicular skeleton--updated. Clinical orthopaedics and related research. 1986 Mar;     [PubMed]
Zumárraga JP,Cartolano R,Kohara MT,Baptista AM,Dos Santos FG,de Camargo OP, TIBIAL ADAMANTINOMA: ANALYSIS OF SEVEN CONSECUTIVE CASES IN A SINGLE INSTITUTION. Acta ortopedica brasileira. 2018;     [PubMed]
Maki M,Athanasou N, Osteofibrous dysplasia and adamantinoma: correlation of proto-oncogene product and matrix protein expression. Human pathology. 2004 Jan;     [PubMed]
Bovée JV,van den Broek LJ,de Boer WI,Hogendoorn PC, Expression of growth factors and their receptors in adamantinoma of long bones and the implication for its histogenesis. The Journal of pathology. 1998 Jan;     [PubMed]
Taylor RM,Kashima TG,Ferguson DJ,Szuhai K,Hogendoorn PC,Athanasou NA, Analysis of stromal cells in osteofibrous dysplasia and adamantinoma of long bones. Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc. 2012 Jan;     [PubMed]
Satyanarayana S,Jawed KZ,Sirohi D,Sikdar J, Adamantinoma of Tibia. Medical journal, Armed Forces India. 2002 Oct;     [PubMed]


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