PURPOSE: To report four pediatric cases of a bone-destructive orbital tumor that proved to be a benign solitary intraosseous myofibroma. METHODS: Four children, aged 1, 7, 11, and 72 months, developed eyelid fullness or slight proptosis. A solitary intraosseous mass was detected in the inferior (n = 2), superotemporal (n = 1), and supranasal (n = 1) orbital walls. On CT, the mass showed bone destruction. On MRI, the mass appeared circumscribed within a shell of normal surrounding bone and with features of isointensity on T1-weighted images, intense homogeneous gadolinium enhancement, and midrange signal on T2-weighted images. Complete surgical excision of the mass in each case was performed. RESULTS: On histopathologic examination, the tumors were characterized by whorls and bands of plump myoid cells with eosinophilic cytoplasm consistent with myofibroblasts, sometimes associated with a hemangiopericytoma-like vascular pattern. The diagnosis was also supported by immunohistochemical studies showing positive immunoreactivity for vimentin and smooth muscle actin. None of the patients have shown recurrence in follow-up ranging from 6 months to 3 years. CONCLUSIONS: Myofibroma is a benign tumor that can occur in the orbital bony wall of children. It can manifest as a bone destructive mass and can simulate a malignant process.
PURPOSE: To report four pediatric cases of a bone-destructive orbital tumor that proved to be a benign solitary intraosseous myofibroma. METHODS: Four children, aged 1, 7, 11, and 72 months, developed eyelid fullness or slight proptosis. A solitary intraosseous mass was detected in the inferior (n = 2), superotemporal (n = 1), and supranasal (n = 1) orbital walls. On CT, the mass showed bone destruction. On MRI, the mass appeared circumscribed within a shell of normal surrounding bone and with features of isointensity on T1-weighted images, intense homogeneous gadolinium enhancement, and midrange signal on T2-weighted images. Complete surgical excision of the mass in each case was performed. RESULTS: On histopathologic examination, the tumors were characterized by whorls and bands of plump myoid cells with eosinophilic cytoplasm consistent with myofibroblasts, sometimes associated with a hemangiopericytoma-like vascular pattern. The diagnosis was also supported by immunohistochemical studies showing positive immunoreactivity for vimentin and smooth muscle actin. None of the patients have shown recurrence in follow-up ranging from 6 months to 3 years. CONCLUSIONS: Myofibroma is a benign tumor that can occur in the orbital bony wall of children. It can manifest as a bone destructive mass and can simulate a malignant process.