Solitary intraosseous orbital myofibroma in four cases

To report four pediatric cases of a bone-destructive orbital tumor that proved to be a benign solitary intraosseous myofibroma.

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.

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.

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.