Silent Pituitary Adenoma in Nasal Cavity

Abstract

Introduction: Silent corticotroph adenomas (SCA) represent 3-6% of all pituitary adenomas. SCA are confirmed on post-surgical histological tumour staining and can either have no prior clinical or biochemical evidence of excess ACTH or alternatively only biochemical (not clinical) evidence of Cushing’s disease. SCA are potentially large and aggressive tumours with a greater tendency to post-surgical recurrence. We present a case of a giant SCA which pre-operatively didn’t exhibit any clinical signs of cortisol excess but showed signs of early recurrence on follow up imaging. Case: A 40-year-old man presented with frontal and maxillary sinus pain and nasal stuffiness. Nasal endoscopy revealed a mass in the nasal cavity and sphenoid sinus. Subsequent CT scan of his sinuses and MRI Pituitary reported a 4 x 3.5 x 2.5 cm sellar mass extending through the floor of sella into the sphenoid sinus and nasal cavity. Despite no clinical features of any pituitary hormone excess (including Cushing’s) or deficiency, his biochemical parameters were consistent with hypercortisolaemia. Post-low dose dexamethasone (2 mg over 48 hours) suppression cortisol was inadequate: 106 nmol/L (<50nmol/L). His corresponding serum dexamethasone level was 8.6 nmol/L (>3nmol/L), ACTH 46 ng/L (0-46 ng/L) and 24-hour urinary free cortisol levels were 502 and 260 nmol/24 hours (<165 nmol/24 hours)) on 2 separate occasions. The remainder of his pituitary profile was normal. He therefore underwent expanded endonasal endoscopic resection of tumour without significant complication. His post-operative cortisol was <50nmol/L (other pituitary hormone measurements normal) so hydrocortisone replacement therapy was commenced. A 3-month post-operative MRI pituitary scan revealed near total resection of the tumour with peripheral enhancement within the tumour resection site representing post-surgical changes. Histopathology showed sparsely granulated, diffuse cytokeratin immunostaining and immunopositivity for ACTH and T-pit consistent with a corticotroph PitNet of the sparsely granulated variety with low Ki 67 index. His six month post-operative scan showed recurrent sellar mass of 2.2 x 0.9 x 1.4 cm. Again there was an absence of clinical features of Cushing’s syndrome. After multidisciplinary discussion clinical, biochemical and radiological surveillance was continued with a view to further transsphenoidal surgery and/or radiotherapy depending on the progress of the tumour. Conclusion: Our patient solely had biochemical (not clinical) evidence of Cushing’s disease despite a large pituitary tumour in keeping with an SCA, which are aggressive, have high recurrence rate and shorter time to recurrence after surgery. Close and frequent post-operative clinical, biochemical and radiological surveillance is critical to detect and manage early recurrence that may require multimodal therapy.