An elderly woman presented with fever, dehydration, orbital inflammation, total external and internal ophthalmoplegia and blindness, resembling the clinical appearance at presentation of severe orbital inflammatory disease or mucormycosis. Orbital computed tomography scanning demonstrated a retrobulbar orbital mass. Subsequent B-scan ultrasound examination confirmed the orbital mass but also demonstrated a mass within the eye. At lateral orbitotomy, extrascleral spread of an entirely necrotic intraocular melanoma was demonstrated. As computed tomography scanning may not be able to delineate an entirely necrotic intraocular malignant melanoma, B-scan ultrasonography should be considered in patients with orbital inflammation, especially in the presence of a retrobulbar mass.