Case 789 -- A 73 year-old man with a mass at the foramen magnum

Contributed by Kieren S J Allinson, BSc Hons, MB ChB1, Angelos G Kolias, MSc, MRCS 2, Yiannis Philippou, MB, BChir2, Diederik O Bulters, BSc, MB, ChB, FRCS (SN)2, Cyril Fisher MA, BM, BCh, MD, DSc, FRCPath, Hon MRCR3, Arie Perry MD4, Andrew F Dean, BM, BCh, FRCPath 1
1Department of Neuropathology Addenbrooke's Hospital and University of Cambridge, Cambridge, UK;
2Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke's Hospital and University of Cambridge, Cambridge, UK;
3Department of Histopathology, Royal Marsden Hospital, London, U.K.;
4Department of Histopathology, University of California, San Francisco, U.S.A.


A 73 year-old male presented with a 6 month history of progressive tetraparesis, during which he had deteriorated markedly from being mobile and performing in a steel band to completely bed-bound. Medical history included ischemic heart disease and type II diabetes mellitus. Neurological examination revealed symmetrical pyramidal weakness, pathologically increased deep tendon reflexes and increased tone in all 4 limbs. Plantar response was upgoing bilaterally. Pinprick-sensation was reduced below the neck. Cranial nerve examination was normal. An MRI scan showed a well-demarcated extra-axial mass on the dorsal surface of the lower medulla/upper cervical cord extending from the level of the clivus to the body of the axis inferiorly (figures 1, 2, 3 and 4). The mass exhibited heterogeneous hyper-intensity on T2W (figure 1), low-to-intermediate signal on T1W (figure 2), and florid enhancement with Gadolinium contrast-agent (figures 3 and 4). The spinal cord exhibited high T2-signal, consistent with edema, from the level of the tumour superiorly to the body of C5 inferiorly. There was no bony erosion or sclerosis, or enhancing dural 'tail'.

Midline posterior fossa craniotomy and C1 laminectomy exposed a sub-arachnoid tumour. This underwent sub-total resection, leaving only a small nodule that was a firmly adherent to the cord. An MRI scan performed two months post-operatively demonstrated partial resolution of the T2 signal change in the cord and confirmed residual tumour less than one centimeter in size. He showed sustained clinical improvement over the next twelve months and is now able to walk and perform some dextrous activities.


Macroscopically, the mass was firm with a smooth creamy-white surface and tan-coloured interior featuring small cystic spaces. Microscopically, the tumour had a hypocellular fibrous capsule (figure 5) circumscribing numerous multi-nucleated cells (figure 6) many of which had a 'floret'-like appearance with radially-arranged peripheral nuclei and some had intranuclear pseudo-inclusions (figures 9 and 10). Intermixed was a second population of short spindle cells. Cytoplasmic vacuolation was focally evident (figure 10). The background varied from densely fibrous to myxoid (figures 7 and 8), with a prominent thin-walled vasculature (figure 11). Very rare mitotic figures were noted but no necrosis, hemosiderin, calcification, lobules or whorls, psammoma bodies or involved nerve. Immunocytochemically, the tumour expressed: bcl2, widely and strongly; CD34, patchily but strong (figure 15); CD99, scattered and weak; S100, rare small-cells considered non-neoplastic (figures 13 and 14); CD68, rare small cells and giant-cells. EMA, GFAP and Olig 2 were negative. The Ki67 labelling index was very low and confined to a minority of the enlarged nuclei (figure 12). What is the diagnosis?


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