Adamantinomas are rare primary malignant bone tumors that in the vast majority of cases occur in the tibia of young patients.

In the past, ameloblastomas, which are benign, locally aggressive bone tumors of the mandible, were also known as adamantinomas of the mandible. The two entities are histologically unrelated, and for this reason, adamantinomas are no longer subcategorised as those of the mandible and those of long bones.

Typically presents in the 2nd to 3rd decades as a locally aggressive mass 3 to 15 cm in diameter. There is a slight male predilection (1.3:1). Patients usually present with dull pain of gradual onset.

The occurrence is almost exclusively confined to the tibial diaphysis (especially the anterior cortex) 2,5. Since it is a low-grade malignancy, it has the propensity to metastasise to distant locations including lung, bone, lymph nodes, pericardium, and liver.

Typically, it appears as a multilocular or slightly expansile osteolytic cortical lesion. This may be visualized as areas of lysis interspersed with areas of sclerosis 3. Lesions tend to have an eccentric epicentre 4 and a lack of periosteal reaction. There may be locally aggressive disease at presentation.

Some authors have distinguished two morphologic patterns 2:

  • solitary lobulated focus 
  • multiple small nodules in one or more foci 

In some patients separated tumor foci may be seen, defined as foci of high signal intensity on either T2- or contrast-enhanced T1-weighted images, interspersed with normal-appearing cortical or cancellous bone 2. A fluid-fluid level may occasionally be seen.

  • C+ (Gd): tends to show intense and homogeneous static enhancement, although there is no uniform dynamic enhancement pattern 2

Surgical, en bloc resection is often performed. It is a locally aggressive tumor with distant metastases reported in around 15% of cases 1

Adamantinoma is derived from the Greek word 'adamantinos', which means 'very hard'. It was first observed in the shaft of an ulna in 1900 by C Maier 8, who believed it was a carcinoma, although the term 'adamantinoma' was coined by B Fisher in 1913 9.

Imaging differential considerations include 6:

Bone tumours

The differential diagnosis for bone tumors is dependent on the age of the patient, with a very different set of differentials for the pediatric patient.

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Article information

rID: 9599
Synonyms or Alternate Spellings:
  • Adamantinomas of long bones
  • Long bone adamantinoma

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