Adamantinoma

Adamantinomas are rare indolent malignant bone tumours with a predilection for the tibial diaphysis. Following excision, local recurrence can be problematic and may occur after an interval of decades. Lymphadenopathy and metastases complicate <30% of cases ¹².

Terminology

Ameloblastomas, which are benign locally aggressive bone tumours of the mandible, were previously also known as adamantinomas of the mandible. Although the histology is similar, a common histogenesis is unproven.

Epidemiology

Adamantinomas account for <1% of primary bone tumours and typically present between the 2^nd and 5^th decades. There is a slight male predilection (M:F = 5:4) ¹².

Clinical presentation

as a locally aggressive mass 3-15 cmSymptoms of pain, swelling and tibial bowing deformity are slowly progressive. A history of prior local trauma may be elicited in diameteraround 60%. Paraneoplastic severe hypercalcaemia with coma and pancreatitis have been reported ¹².

Pathology

The histogenesis remains uncertainthe subject of debate. The histology is heterogeneous and epithelial, synovial, endothelial and osseofibrous components have been demonstrated. Extensive sampling of the most radiolucent areas is recommended ¹².

Location

occurrenceOccurrence 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.

Radiographic features

Plain radiograph / CT

Typically, it appears as a multilocular or slightly expansile osteolytic cortical lesion. This may be visualised 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.

MRI

Some authors have distinguished two morphologic patterns ²:

• solitary lobulated focus 

• multiple small nodules in one or more foci 

In some patients separated tumour 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.

• T1 C+ (Gd): tends to show intense and homogeneous static enhancement, although there is no uniform dynamic enhancement pattern ²

Treatment and prognosis

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

History and etymology

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.

Differential diagnosis

Imaging differential considerations include ⁶:

• chondromyxoid fibroma

• fibrous dysplasia

• osteofibrous dysplasia: has a more ground-glass texture on CT