Low grade myxofibrosarcoma in the orbit: A case report

A case of low-grade myxofibrosarcoma in the orbit is described. A 52- year-old woman with a soft mass on the left eyelid was first operated on in 1988. The pathological diagnosis was fibrolipoma. She revisited our clinic for swelling of the eyelid and exophthalmos 4 years later. Reduction of the tumor was performed and the diagnosis was myxoid-neurofibroma even though it looked recurrent. A residual tumor gradually grew up over a 4 year period resulting in severe exophthalmos. A third reducing operation was performed in 1998 for improving her figure and the exophthalmos. The tumor invading the ocular muscles was an unclearly-clearly-circumscribed myxoid mass without detectable capsulation or nodular formation. Microscopically, the tumor was characterized by the proliferation of sparsely distributed spindle cells, well-developed capillary vessels, and myxoid stroma. It demonstrated mild pleomorphism without mitotic figures. There was no lipoblast. Immunohistochemically, the tumor cells were positive for vimentin, but negative for alpha-smooth muscle actin (IA-4) and muscle specific actin (HHF 35). For S100 protein, the cells were stained slightly, but the axon like structures were neither stained nor detected. Therefore, we concluded that this tumor was a low-grade myxofibrosarcoma instead of a chance nodular formation. We re-examined the specimens obtained in the previous two operations and found cells similar to those shown in the final specimen. Low- grade myxofibrosarcoma, which is commonly mistaken as benign, has a tendency for histological and biological progression in local recurrence. Especially, in head and neck lesions, it is important that accurate diagnosis and wide surgical excision of the primary lesion are performed at the first operation.