Ultrasound diagnosis of orbital histiocytofibromas

Summary

Fibrous histiocytomas are not rare. The diagnosis of fibrous histiocytoma might be evoked in case of a well circumscribed, heterogenous tumor, with bony deformation and no bony erosion. New B-mode equipment with high energetic, high resolution good gray scale probes proved to be very helpful, giving as much information as Standardised A-mode. It is always possible to differentiate such a tumor from cavernous hemangioma. Unfortunately, differential diagnosis with hemangiopericytoma and peripheral nerve sheath tumors is not always possible.

Fibrous and connective tissue tumors are rare. They include fibromas, fibrosarcomas and fibrous histiocytomas (hystiocytofibromas).

Pure fibromas are extremely rare. One mainly sees angiofibromas, fibrolipomas and fibromyosarcomas. Fibromas have to be differentiated from nodular fasciitis and from fibrosarcoma. Fibrosarcoma has been reported mostly in children, most frequently after irradiation for retinoblastoma.

Fibrous histiocytoma (histiocytofibroma, fibroxanthoma) is the most common mesenchymal orbital tumor. It was frequently misdiagnosed by the pathologists. This explains the very low frequency of the cases reported in two large series [1, 2] of orbital tumors. Nevertheless, the orbit is a site of predilection for this tumor.

They usually are benign lesions, well circumscribed and cystic myxoid and hemorrhagic areas may also be noted. Usually hemorrhage is seen in malignant tumors. Recurrence of the lesion is linearly related to the aggressivity and the malignancy of the tumor. Microscopically, there is variable admixture of spindle-shaped fibroblast like cells and hystiocytic cells.

We report 4 cases of fibrous histiocytoma. They all happened in an adult: 3 intraconal lesions and 1 extraconal inferolateral lesion. All the lesions were well delineated. The good limitation of the anteriorly situated lesion was more difficult to appreciate.