Low-Flow Orbital Venous Malformation Masquerading as Rhabdomyosarcoma.

A 15-month-old male was referred for biopsy of presumed rhabdomyosarcoma in the setting of rapidly progressing left-sided proptosis. Examination revealed left periorbital edema and left hypoglobus. MRI revealed a soft-tissue density mass within the left lateral retrobulbar space. Several days later, he developed acute periorbital ecchymosis and increasing edema. With high suspicion for a vascular lesion, a CT scan was performed with dynamic arterial and venous imaging. Central filling was noted in the lateral retrobulbar component with increased enhancement on delayed venous imaging in the middle cranial fossa component favoring the diagnosis of a low-flow orbital venous malformation. In the setting of spontaneous orbital hemorrhage and risk of future vision loss, the decision was made to proceed with a combined neurosurgical approach treating the intracranial component and debulking the orbital component. This case highlights the importance of thorough radiographic evaluation prior to proceeding with a surgical procedure in the appropriate clinical context.