Adamantinoma is a primary low-grade, malignant bone tumor that is predominantly located in the mid-portion of the tibia. The aetiology of the tumor is still a matter of debate. Histologically, classic adamantinoma is a biphasic tumor characterized by epithelial and osteofibrous components that may be intermingled with each other in various proportions and differentiating patterns.

We report here a particular morphologic variant of adamantinoma characterised by the loss of classic epithelial differentiation. A 17 year-old teenager presented with a long history of a tumor in the left leg. Explorations revealed an osteolytic lesion of the middle shaft of the left tibia with a huge mass invading soft tissues. An intra medullar bone lesion with benign appearance was observed in the right tibia. CT of the chest revealed lung metastases. Histologically, we observed in the left side a pattern of spinde-celled high grade sarcoma without any evident differentiation. Spindle-shaped tumor cells express cytokeratins and vimentin. Ultrasturctural study showed tonofibrils and desmosomes and was helpful to recognize the epithelial nature of the tumour. The diagnosis of dedifferentiated adamantinoma was retained. In the right tibia biopsy revealed fibrous dysplasia. Amputation above the knee was performed followed by chemotherapy. One year later, the patient is still alive with multiple lung metastases.

In our study, we discussed the clinico-pathologic features of this particular pattern of adamantinoma as well as its association with fiobrous dysplasia in this case. A review of literature was done.

Clear cell meningioma is a rare subtype of meningiomas graded II according to the World Health Organisation classification. In spite of its benign appearance, clear cell meningioma has an aggressive behaviour and it is characterized by its inordinately tendency to metastasize.

The purpose of this study is to discuss the clinico-pathological features of this subtype of meningiomas as well as the metastatic pathways.

We wish to report a rare case of a clear cell meningioma metastasizing to the sacrum 17 years after the removal of the primary tumour. A 26 year-old man was referred to our centre for low back pain related to a lytic lesion of the sacrum. He had a history of a tumour of the forth cervical vertebra that was removed when he was 9 year-old. CT scan revealed an osteolysis of the entire sacrum invading the intrapelvic organs and the sacro-iliac joints. Open biopsy revealed a clear cell meningioma. That was the same pattern of the tumour removed 17 years earlier. Chest CT showed lung metastases. The patient was managed conservatively by palliative radiation therapy. One year later, he experienced improvement of pain and walk. The mass was stable.

Clear ell meningioma is an aggressive tumour with a potential to spread via cerebro-spinal fluid and haematologically. Patients with such a tumour should be closely followed for a long time.