Contributed by Marian C Neidert1, Henning Leske2, Karl Frontzek2, Beata Bode3, David Capper4, Luca Regli1, Elisabeth J Rushing2
1Department of Neurosurgery, University Hospital Zurich, Switzerland
2Institute of Neuropathology, University Hospital Zurich, Switzerland
3Department of Surgical Pathology, University Hospital Zurich, Switzerland
4Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg
A 49-year old female with no significant past medical history except for psoriasis presented to our department complaining of increasing neck pain over 4 weeks accompanied by hoarseness and dysphagia. In addition, she reported general fatigue as well as problems with fine motor skills of her right arm and right leg. On MRI we found a left anterolateral extra-axial space-occupying lesion (45 x 32 x 32 mm) of the foramen magnum that shifted the brain stem to the right, another small para-torcular (8mm) extra-axial lesion over the left cerebellar convexity and an extra-axial mass over the right sylvian fissure (shown in Figs. 1a and 1b). Considering the clinical symptoms of the patients, we opted for surgery of the foramen magnum tumor and the small peritorcular lesion of the left cerebellar convexity due to its proximity. After angioembolization of the supratentorial tumor and foramen magnum mass, a far lateral suboccipital craniotomy was performed on the left side in park bench position. Surgery was complicated by the difficult anatomy with the lower cranial nerves and brain stem perforators of the vertebral artery running on the surface of the tumor. Using a combination of intratumoral ultrasonic aspiration and peritumoral microdissection, the foramen magnum mass could be removed completely and the dural attachment was coagulated (corresponding to a Simpson grade II resection in meningioma surgery). The small para-torcular lesion had a clear arachnoidal plane and could be completely resected without complications. The patient had no new postoperative neurological deficits and the postoperative MRI showed a complete resection of both lesions ( Figs. 1a and 1b). At three months follow-up, the preoperative symptoms recovered completely. The foramen magnum mass was diagnosed as a WHO grad I meningothelial meningioma - the diagnosis of the smaller cerebellar para-torcular mass is discussed below in detail.
The resected specimen was firm and gray and measured 1.3 x 0.7 x 0.7 cm. Microscopically, the richly vascular tumor displayed rudimentary whorls and was composed of uniform, bland, oval to spindle cells with abundant eosinophilic cytoplasm. In many areas, tumor cells surrounded a small vascular lumen. In other areas, ectatic, hemangiopericytoma-like vascular channels interrupted the neoplastic proliferation (Figs. 1c, 1d, 1e and 1f). Mitotic figures were not observed. Immunohistochemically, there was patchy staining for caldesmon (Fig. 1g), but the tumor cells were negative for EMA (Fig. 1h) and CD34 (Fig. 1i) as well as Epstein-Barr virus and BRAF-V600E mutation. However, the tumor cells also uniformly expressed small muscle actin (SMA) (Fig. 1j). The MIB1 proliferation index was less than 1%. What is your diagnosis?