An unusual case of a pituitary fossa aspergilloma in an immunocompetent patient mimicking infiltrative tumour
A 90-year-old female presented with 3 months of generalized headaches, anorexia and nausea. She was alert, afebrile, and haemodynamically stable, and neurological examination was unremarkable. Her past medical history included a localized bowel cancer resection and skin melanoma excision several years prior, as well as hypertension. She did not have diabetes mellitus, HIV infection or any previous chemotherapy or immunomodulatory therapies for melanoma. There was no history of craniofacial trauma. Her regular medications included ramipril. Routine investigations including full blood count, serum electrolytes and C-reactive protein were normal. A pituitary hormone screen was normal apart from mildly elevated serum prolactin at 714 mU/ml (normal <536 mU/ml). Routine chest X-ray was also unremarkable.\nA computed tomography (CT) brain demonstrated dehiscence of the floor of the sella and mucoperiosteal thickening in the sphenoid sinus with some curvilinear calcification (Fig. A). Magnetic resonance imaging (MRI) brain revealed a contrast-enhancing mass within the superior aspect of the sphenoid sinus communicating with the pituitary fossa through the defect of the floor of the sella, measuring 12 mm in maximal craniocaudal dimension. The pituitary gland appeared to be heterogeneous in signal intensity on both pre-contrast T1- and T2-weighted sequences and demonstrated heterogeneous enhancement post-Gadolinium contrast administration (Figs and ). The imaging findings suggested a pituitary neoplasm with a downward growth pattern. However, the mucoperiosteal thickening in the sphenoid sinuses and the presence of calcification on CT raised the possibility of a mycetoma.\nThe patient's headache worsened despite management with simple analgesia. A repeat MRI performed 3 weeks after presentation demonstrated that the lesion had expanded in size and appeared to be breaching the diaphragma sella, with extension to the inferior surface of the optic chiasm (Fig. ).\nThe patient underwent stereotactic-guided endoscopic transnasal transsphenoidal surgery. The sphenoidal sinus mucosa was exenterated via an endoscopic endonasal incision, and abnormal irregular friable yellow tissue was removed from clival and sella portions of the posterior wall of the sphenoidal sinus. Invasive fungal hyphae were demonstrated on histopathological frozen section. There was no evidence of dural extension and the remaining abscess material was removed without breaching dura. Post-operatively, amphotericin-B was initiated. Fungal cultures of the biopsy specimens later identified the growth of Aspergillus fumigatus, and she was initiated on 400 mg/day oral voriconazole. The patient's headaches resolved almost completely after the operation. Her post-operative course was complicated by visual and tactile hallucinations and hyponatremia (Na+ 123 mmol/l). Serum and urine osmolalities were 261 mmol/kg (normal 280–303 mmol/kg) and 439 mmol/kg, respectively, and the urinary sodium was 41 mmol/l. The patient remained euvolaemic and there was no post-operative polyuria. The patient's cortisol level was 665 nmol/l (normal 155–600 nmol/l) and thyroid-stimulating hormone level was 1.1 mU/l (normal 0.1–3.8 mU/l). The hyponatraemia and hallucinations were believed to be the result of a syndrome of inappropriate anti-diuretic hormone syndrome (SIADH), a complication of surgery of the sellar region and possibly also a side-effect of the voriconazole, which was temporarily withheld. She was given risperidone, which resolved her hallucinations. Three months after surgery, the patient had no neurological complaints. Repeat MRI at this stage showed persisting mucoperiosteal thickening with post-surgical changes in the sphenoid sinus, but no evidence of a mycetoma.