Contributed by Susann Hetze1, MD, Johannes van de Nes2, MD, Sophia Goerike3, MD, Sarah Teuber-Hanselman2, MD, Ulrich Sure1, MD, Neriman Oezkan1, MD
1Department of Neurosurgery, 2Institute of Neuropathology, 3Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Germany
A 33-year-old male patient reported on head and neck pain radiating into the left maxilla, that had already persisted for 5 years presented in the clinic, as he experienced an acute neuralgic pain provoked by physical activity (VAS 8/10 points) as a new symptom. MRI showed a left-sided hypointense, polyglobulated tumor in the left cerebello-pontine angle, with irregular contrast enhancement and hypointensity on T1 and T2 images (Figs. 1a, 1b, 1c). The tumor exerted pressure on the medulla oblongata, resulting in perifocal edema. By cranial CT (Fig. 1d) the tumor had a strong hyperdense signal. The patient complained of no other neurological deficits. The tumor was extirpated microneurosurgically using electro-physiological monitoring via retromastoidal approach and semisitting position of the patient. Since the lesion was adjacent to the brain stem, a thin layer was left (intraoperative pictures of the tumor: Figs. 1e, 1f). Postoperatively, the patient sustained a new facial and glossopharyngeal palsy, which considerably improved at 3 months' follow-up.
The tissue contained multiple pieces, grey white, soft to hard, measuring 8 x 8 x 8 mm. Histological examination showed amorphic tissue that was partly characterized by a lobulated appearance. At the periphery of the lobules cells with epithelioid appearance and a radial orientation, were seen (Fig. 1g). Other areas had fibrohistiocytic tissue with multinucleated cells (Fig. 1h). There was also fibro-osseous metaplasia including osteoclasts and calcifications, surrounded by collagenous fibrovascular strands (Fig. 1i). Adjacent central nervous tissue showed reactive gliosis. There was no necrosis. Immunostains were negative for MNF 116 (pancytokeratin), CK8, GFAP, Synaptophysin, S100 protein, actin, desmin, p53 and IDH-1-R132H mutation. A part of the epithelioid cell elements expressed EMA (Fig. 1j) and KiM1P1 (macrophage marker) (Fig. 1k). The Ki67 proliferation index in those cells was about 5% (Fig. 1l). What is your diagnosis?