Leiomyoma and leiomyosarcoma of the orbit.

Comparison of the clinical and pathologic features of two orbital leiomyomas, two leiomysarcomas, and one embryonal rhabdomyosarcoma showed the leiomyomas occurred in young individuals and the leiomyosarcomas in older patients. The histopathologic diagnosis rested on the intense cytoplasmic eosinophilia and nostriated longitudinal cytoplasmic filaments demonstrated by means of the trichrome stain. The leiomyosarcomas disseminated 15 months and seven years after their orbital presentations. The treatment of both leiomyoma and leiomyosarcoma is surgical. Leiomyomas are encapsulated growths that may have small satellite nodules projecting from the main tumor mass; thus, a margin of normal tissue should also be excised, lest a small lobulation be left behind to serve as the seed for a late recurrence. Once the diagnosis of leiomyosarcoma has been made, and no evidence of metastasis has been found after a thorough systemic evaluation, the orbit should be exenterated, because the tumor is unencapsulated and liable to widespread dissemination. Rhabdomyosarcoma has a much more fulminant course than leiomyosarcoma, and especially more so than that of leiomyoma of childhood. The histopathologic diagnosis of a malignant smooth muscle tumor in a child should always be questioned, since embryonal rhabdomyosarcoma is a much more likely diagnosis.