CASE 14946 Published on 18.08.2017

Tibial long-standing lesion

Section

Musculoskeletal system

Case Type

Clinical Cases

Authors

Abreu I., Roriz D., Moreira A., Caseiro-Alves F.

Centro Hospitalar e Universitário de Coimbra,
Radiology;
Portugal.
Patient

14 years, female

Categories
Area of Interest Musculoskeletal bone ; Imaging Technique MR, CT
Clinical History
A 14-year-old female patient was referred to orthopaedics due to long-standing mild pain in the anterior surface of the middle third of the right tibia, with 3 years of evolution. In the past 4 months she noted a swelling in this location and an increase in pain intensity. There were no previous radiology studies.
Imaging Findings
The plain film (Fig. 1) reveals the presence of small cortical lytic lesions with poorly defined margins on the anterior surface of the tibia. CT (Fig. 1) demonstrates also the associated soft tissue component. There is no periosteal reaction.
On MRI the soft tissue component is better demonstrated. This lesion has a bone origin (anterior cortex of the tibial diaphysis) with cortical rupture and a soft tissue mass, which is hypointense on T1WI and hyperintense and heterogeneous on T2WI (Fig. 2). The lesion shows evident enhancement after contrast administration (Fig. 3).
No other lesions are seen in the remaining tibia.
Discussion
Background:
Adamantinoma is a rare malignant neoplasm (0.1 to 0.4% of primary bone tumours) that occurs almost exclusively in the anterior cortex of the tibial shaft. There are cases described in other long bones (humerus, femur, fibula and radius). [1, 2]
This is a low-degree but locally aggressive neoplasia that is characterised by epithelial and osteofibrous components consisting of islands of epithelial cells within a fibrous stroma with peripheral palisading in fibrous stroma with haphazard osteoid deposition. Keratin staining is typically positive. [1, 2]

Clinical Perspective:
It typically presents in the 2nd and 3rd decades of life with a male predilection (M:F ratio of 1.3: 1) with gradual pain with or without a palpable mass. 25% have symptoms for 5 or more years.
This is a low-degree but locally aggressive neoplasia with a cortical origin. In about 15% of the cases there is cortical rupture and soft tissue mass. [1, 3]

Imaging Perspective:
Radiography and CT:
It usually presents as an elongated lytic cortical lesions with poorly defined margins interspersed with sclerotic areas. Lesions tend to have an eccentric epicentre and no aggressive periosteal reaction. [1, 3, 4]

MRI:
Single or multi-focal lesions (importance of MRI) hypointense on T1WI and hyperintense on T2WI. The post-contrast enhancement is variable but usually intense. There may be cortical rupture and soft tissue mass and in some cases liquid-liquid levels. [1]

Outcome:
Good prognosis.
Adamantinoma is a low degree of malignancy but locally aggressive. [1]
Metastatic disease in 15% of cases: lung, bone, liver and lymph nodes.
Treatment: block surgery. Does not respond to QT or RT.
Local recurrence: 8 - 32%. [1, 2]

Take Home Message, Teaching Points:
Diaphysial lesion of the tibia in a young patient - think about adamantinoma, even if it is a rare tumour.
Differential Diagnosis List
Adamantinoma of the anterior tibial diaphysis
Fibrous dysplasia
Osteofibrous dysplasia
Chondromyxoid fibroma
Ewing's sarcoma
Final Diagnosis
Adamantinoma of the anterior tibial diaphysis
Case information
URL: https://eurorad.org/case/14946
DOI: 10.1594/EURORAD/CASE.14946
ISSN: 1563-4086
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