Contributed by Julia Velz1,2, David Bellut1,2, Niklaus Krayenbühl1,2, Sebastian Winklhofer2,3, Elisabeth Rushing2,4, Katrin Frauenknecht2,4
1Department of Neurosurgery, 2University of Zurich, 3Department of Neuroradiology, 4 Institute of Neuropathology, University Hospital Zurich, CH-8091 Zurich, Switzerland
In 2002, a 55-year old male patient was referred for neurosurgical consultation after two episodes of speech arrest and a newly diagnosed mass lesion in the superior left temporal gyrus extending to the insula. The patient underwent a pterional craniotomy with partial resection of the tumor. Histopathological examination revealed an oligodendroglioma (WHO II). A follow-up MRI in 2007 demonstrated significant growth of the residual tumor mass (Fig. A-D). Accordingly, the patient was started on standard therapy with Temozolomide. In 2011, MRI showed tumor progression, which prompted additional tumor resection. Histological examination revealed features of anaplastic oligodendroglioma with co-deletion of 1p/19q. Postoperative treatment included adjuvant radiotherapy (32 x 1.8 Gy = 57.6 Gy). In June 2015, follow-up MRI revealed a local recurrence consistent with tumor progression. Meanwhile, the patient had undergone surgical resection of an adenocarcinoma of the colon, diagnosed in 2015, and treated with adjuvant chemotherapy (FOLFOX4). The decision was made to suspend further treatment and to follow the patient with MRI. Of note, regression of the tumor mass was observed in the parahippocampal gyrus.
In September 2016, 14-years after the initial diagnosis of oligodendroglioma, follow-up MRI of the liver was performed according to the staging protocol for metastatic adenocarcinoma. MRI of the abdomen revealed the incidental finding of an intradural tumor attached to the conus medullaris. MRI of the lumbar spine showed a circumscribed, intradural, extramedullary tumor (11 x 13 x 24 mm). The tumor occupied the spinal canal between Th12-L1, shifting the conus to the left, as well as infiltrating the fibers of the cauda equina (Fig. E-H). Clinical examination revealed mild paresis of the right leg, in particular, the right hip and foot flexors (M4/5).
Laminoplasty was performed at Th12-L1 and the intradural, intramedullary lesion was resected. The postoperative course was uneventful and the patient did not show any new deficits after surgery (Fig. I-L, postoperative MRI). The histological diagnosis is discussed below in detail.
Multiple tissue fragments measuring 8 x 8 x 1 mm in total were submitted for histological examination. Microscopic examination revealed a neoplasm composed of closely packed, relatively uniform round cells with perinuclear halos. Frequent mitoses were observed, which were accompanied by microvascular proliferation, and pseudopalisading necrosis (Fig. 2a, 2b,2 c). Scattered calcospherites were present. The nuclei and cytoplasm of the tumor cells were immunoreactive for the IDH1R132H-mutation. ATRX immunohistochemistry showed retained nuclear expression. The tumor cells were epithelial membrane antigen (EMA) negative and glial fibrillary acidic protein (GFAP) positive (Fig. 2d, 2e). The MIB1-proliferation index was high, reaching 50% (Fig. 2f). What is your diagnosis?