Intraconal hybrid neurofibroma ‐ schwannoma of the orbit

Abstract

PurposeAmong peripheral nerve sheet tumors, an orbital hybrid neurofibroma‐schwannoma has been described twice. We describe a third case of orbital tumor with features of both a neurofibroma and a schwannoma.MethodsCase report. A 39 year old man presents with diplopia and decreased vision (0.6) in the left eye. He has a proptosis of 7 mm, with mechanical restriction of elevation and horizontal eye movements. MRI shows a well‐defined lesion (2,5 x 1,9 x 2,3 cm) in the superotemporal intraconal space, displacing the globe, optic nerve and superior and lateral rectus muscles. The tumor demonstrates heterogeneous contrast enhancement, and is diagnosed as a probable cavernous hemangioma. Through a transconjunctival approach a red‐blueish lesion was found with a thin capsule and without lateral adhesions. The tumor could be extracted in 2 parts and consisted of a yellow/white coherent soft mass.ResultsPatient had complete recovery of visual acuity, and only diplopia in extreme lateral gaze. The pathology revealed a tumor composed of small spindle cells arranged in fascicles. The cells showed no atypia and there was no mitotic activity. There were also less cellular areas with a myxoid component. At places we could recognize a fibrous capsule surrounding the tumor. The tumor cells were strongly and diffuse positive with S100. In a few enclosed axons there was focal reactivity with neurofilament. The image is that of a neural tumor with features of both a neurofibroma and a Schwannoma.ConclusionsThis is the third reported orbital hybrid neurofibroma‐schwannoma. Although this type of tumor elsewhere in the body is often associated with schwannomatosis and neurofibromatosis, our patient did not show signs of systemic involvement.