Myxofibrosarcoma of the orbit: an underrecognized entity? Case report and review of the literature.

Purpose: To describe the clinicopathologic and immunohistochemical features of a rare case of myxofibrosarcoma (MFS) involving the orbit.

Design: Retrospective interventional case report and review of literature.

Methods: The clinical history, systemic imaging studies, and histopathologic results of the orbital biopsy are reviewed.

Main Outcome Measures: Clinical, radiologic, and histologic features of MFS.

Results: A 63-year-old Chinese male sought treatment for a history of rapidly progressive proptosis associated with decreased vision in the left eye over 10 days. Magnetic resonance imaging of the orbit revealed a homogenous mass extending to the optic canal. The mass was excised partially and was submitted for histologic and ultrastructural examination. Histologic testing revealed features of MFS with characteristic diffuse proliferation of atypical, spindle-shaped fibroblasts with prominent myxoid stroma. Tumor cells were reactive for vimentin. Ultrastructural examination revealed spindle-shaped tumor cells, rich in dilated rough endoplasmic reticulum and prominent vacuoles.

Conclusions: For historical reasons, MFS involving the orbit is likely to be underrecognized and categorized erroneously as malignant fibrous histiocytoma or other soft tissue sarcoma. Although orbital MFS is an extremely rare diagnosis, ophthalmologists should be aware of the possibility and consider a diagnosis of MFS when an adult seeks treatment for an orbital tumor with aggressive growth.