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Tumor biology and incidence

  • Primary low-grade, locally aggressive, malignant bone tumor of unknown histogenetic origin
    • Current opinion suggests may be epithelial in origin
  • Slow-growing tumors with limited propensity for metastasis and local recurrence; usually amenable to curative resection
  • May arise from osteofibrous dysplasia
  • Very rare neoplasm; estimated 0.1-0.5% of all primary bone tumors
    • First reported example attributed to Maier in 1900; Fischer in 1913 named lesion "primary adamantinoma of the tibia" due to its resemblance of mandibular amelobastoma
  • Location is predominantly in the tibial diaphysis, but can occur in the fibula and other long tubular bones


  • Most commonly occurs in the second to fifth decades
  • Median patient age 25-35 years; range, 2 to 86 years
  • Rarely occurs in children


M:F = 1:1


  • Initial symptoms often indolent and nonspecific; depend on location and extent of disease
  • Insidious onset, slow progressive character; patients often tolerate symptoms for many years before seeking medical attention
  • Lesion may be discovered incidentally on radiographs after patient experiences trauma to involved extremity
  • May present with complaints of dull ache or nonspecific bone pain present for months to years

Physical findings

  • Pretibial soft tissue swelling with or without pain
  • Possibly bowing deformity of tibia due to involvement of anterior tibial surface
  • Pathological fracture may be present in nearly to one quarter of patients
  • Spinal lesions may be manifested by neurologic symptoms in addition to pain

Plain films

  • Classic location in the tibial diaphysis (90% of cases)
    • Appears as a central or eccentric, multilocular, slightly expansile, sharp or poorly delineated osteolytic lesion
    • Metaphyseal extension or isolated involvement may occur
  • Other sites of involvement (in order of decreasing frequency): humerus, ulna, femur, fibula, innominate bones, ribs, spine, small bones of hand/foot.

Varying sizes; typical range, 3-15 cm

Tumor effect on bone
  • Multiple osteolytic defects of varying sizes
  • Bony expansion common
  • Lesions typically geographic and well defined
    • More aggressive lesions may have moth-eaten borders
Bone response to tumor
  • Eccentric lucencies with surrounding reactive bony sclerosis
  • Cortex may be eroded; well organized periosteal expansion

Osteolytic; variable regions of mixed ground glass density


Anterior cortically based lesion in tibia

Soft tissue mass

May be present

Bone scan and chest CT

  • Necessary for systemic staging
  • Bone scan Will likely show increased blood flow in the region of the tumor, increased blood pooling, and increased accumulation of technetium-99m methylene diphosphate
    • May also show coexisting fibular involvement

CT scan

  • Not specific in the differentiation of adamantinoma from other conditions
  • Shows cortical involvement and soft tissue extension when it exists


  • Best for local staging of intra- and extra-osseous tumor extent
  • Not specific in the differentiation of adamantinoma from other conditions
  • Depicts distant cortical foci, soft tissue, and intramedullary extension; therefore, useful for determination of tumor-free margins and preoperative planning for reconstructive surgery

Differential diagnosis

  • Osteofibrous dysplasia
  • Fibrous dysplasia
  • Aneurysmal bone cyst
  • Unicameral bone cyst
  • Chondromyxoid fibroma
  • Giant cell tumor
  • Eosinophilic granuloma
  • Nonossifying fibroma
  • Hemangioendothelioma of bone
    • Will also present with multiple separate regions of bone involvement
  • Osteomyelitis
  • Chondrosarcoma
  • Metastases


  • Gross: Varies, but most often tumor is yellow-gray or gray-white and fleshy or firm in consistency
    • Epithelial and osteofibrous components; intermingled in various proportions and differentiating patterns
  • Microscopic: Neoplastic cells ranging from small to large in size, with finely dispersed chromatin and overall bland appearance; mitotic figures usually infrequent
    • Several patterns of growth: tubular, basaloid (classic), squamous, spindle-cell, osteofibrous dysplasia-like variant
  • Classified into 2 distinct types: classic and differentiated (osteofibrous dysplasia-like)
    • Regardless of histologic subtypes, all adamantinomas uniformly stain positive for keratins 14 and 19
  • IHC: Epithelial cells show coexpression of keratin and vimentin
  • Cytogenetic analysis has revealed extra copies of chromosomes 7, 8, 12, 19, and/or 21 in classic and differentiated adamantinomas

Natural history

  • Locally aggressive but extremely slow growing
  • Have the potential to metastasize (lung, lymph nodes, bone, abdominal viscera)
    • Metastases occur in about 15-30% of cases, by both hematogenous and lymphatic routes
  • Recurrence frequent after inadequate treatment (ie, marginal resection)
    • Recurrent neoplasm behaves more like a sarcoma
    • Local recurrence rates vary from 18-32%
  • No correlation between tumor histology and clinical course
    • Unfavorable clinical outcomes associated with other factors, such as intralesional treatment, male gender, pain at presentation, short duration of symptoms, young age (<20 years), and lack of squamous differentiation of the tumor
  • Determining mortality statistics difficult due to rarity of adamantinomas; however, mortality rates of 13-18% have been reported

Diagnosis and treatment

  • Biopsy, in consultation with a musculoskeletal oncologist
  • Adamantinoma highly radioresistant, and chemotherapy has not been shown to be effective
  • Surgery is current standard of care: amputation or en bloc resection with wide margins and limb salvage
    • Wide margins associated with a significantly lower risk of local recurrence
    • En bloc resection with wide margins and limb salvage has 10-year survival rate of 82% (Qureshi et al)
    • Amputation not shown to improve survival when compared with limb-preserving surgery
  • Limb reconstruction can be performed with distraction osteogenesis, allografts, vascularized fibular autografts, nonvascularized autografts, and metallic segmental replacement
    • Intercalary reconstruction appears to be most successful method; no consensus in literature, however, regarding which is superior form of fixation


Reconstruction-related complications: nonunion, fracture, infection

Recommended reading

Qureshi et al  Current Trends in the Management of Adamantinoma of Long Bones  JBJS August 2000: Vol 82 A, No. 8, pg 1122-1131

Jain et al  Adamantinoma: A clinicopathological review and update  Diagnostic Pathology Feb 2008, 3:8

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