Contributed by Julia Keith-Rokosh1, Gary Ferguson2 and Robert Hammond1
Departments of Pathology1 and Clinical Neurological Sciences, Division of Neurosurgery2, London Health Sciences Centre, University of Western Ontario
A 59 year old male teacher developed symptoms of pan-hypopituitarism. MRI revealed a solid homogeneously enhancing mass in the sella measuring 1.8 cm extending into the suprasellar cistern causing mild compression of the optic chiasm (Fig 1). Neurological exam was normal other than a small bitemporal visual field defect. The lesion was suspected to be a pituitary adenoma, and a transsphenoidal resection was performed. Intra-operatively, the lesion was noted to be posterior to the anterior pituitary gland. Post-operatively, a small amount of residual tumour was present which has been stable on follow-up neuroimaging. No adjuvant therapy was given.
The resected specimen consisted of a fascicular and storiform arrangement of elongated cells with abundant eosinophilic cytoplasm lacking granularity (Fig 2). The nuclei were spindled and monotonous with fine chromatin and small nucleoli (Fig 3). No mitotic figures were seen. Immunohistochemical studies for chromogranin and pituitary hormones were negative. The lesional cells expressed GFAP (Fig 4), Protein Gene PGP9.5 (focal) and S100 (weak). Electron microscopy showed lesional cells bearing abundant intermediate filaments and rare neurosecretory granules (Figs 5, 6).