Pituitary xanthogranulomas: clinical features, radiological appearances and post-operative outcomes

Abstract

Background: Xanthogranulomas are inflammatory masses most commonly found at peripheral sites such as the skin. Sellar and parasellar xanthogranulomas are rare and present a diagnostic challenge as they are difficult to differentiate from other sellar lesions such as craniopharyngiomas and Rathke's cleft cysts pre-operatively. Their radiological imaging features are yet to be clearly defined, and clinical outcomes after surgery are also uncertain. This study reviews clinical presentation, radiological appearances, and clinical outcomes in a cohort of patients with pituitary xanthogranulomas.

Methods: A prospectively maintained pituitary surgery database was screened for histologically confirmed pituitary xanthogranulomas between May 2011-December 2016. Retrospective case note assessments were then performed by three independent reviewers. Patient demographics, clinical presentations, imaging, and clinical outcomes were analysed.

Results: During the study period 295 endoscopic endonasal pituitary surgeries were performed. Six patients had confirmed pituitary xanthogranulomas (2%). Patients most commonly presented with visual field deficits and/or endocrine dysfunction. Common imaging features included: a cystic consistency, hyperintensity on T1-weighted MR images, and contrast enhancement either peripherally (n = 3) or homogenously (n = 3). The most common pre-operative endocrine deficits were hyperprolactinaemia and hypoadrenalism (at least one of which was identified in 4/6 patients; 66%). Thirty-three percent (2/6) of patients presented with diabetes insipidus. The most common post-operative endocrinological deficits were adrenocortical dysfunction (66%) and gonadotropin deficiency (66%). Visual assessments normalised in all six patients post-operatively. Gross total resection was achieved in all patients, and at median follow up of 33.5 months there were no cases of tumour recurrence.

Conclusions: The prevalence of pituitary xanthogranulomas in our series is higher than that suggested in the literature. Surgery restored normal vision to all cases, however four patients (67%) required long-term hormonal replacement post-operatively. Imaging features such peripheral rim enhancement, a suprasellar tumour epicentre, and the absence of both calcification or cavernous sinus invasion were identified as potential indicators that together should alert clinicians to the possibility of pituitary xanthogranuloma when assessing patients with cystic sellar and parasellar tumours.

Keywords: Cystic; Pituitary; Sellar; Xanthogranuloma.

Fig. 1

The method utilised to evaluate suprasellar tumour growth, adapted from Petrakakis et al. The four quadrants used to define tumour expansion are outlined; the quadrant housing the tumour epicentre, and growth within each quadrant, can be assessed individually. Quadrant 1 represents the suprasellar preinfundibular region, quadrant 2 the suprasellar retroinfundibular region, quadrant 3 the clival sellar region, and quadrant 4 the nasal sellar region. Adapted from: Petrakakis et al. [3] The sellar and suprasellar region: A “hideaway” of rare lesions. Clinical aspects, imaging findings, surgical outcome and comparative analysis. Clinical Neurology and Neurosurgery. 149:154–165

Fig. 2

Case 5—Exemplar MR imaging findings in pituitary xanthogranuloma. There is a cystic lesion demonstrating peripheral rim contrast enhancement, and a tumour epicentre identifiable in quadrant 1. a T1 weighted sagittal (post-contrast); mixed intensity lesion with predominantly high T1W signal centrally, and peripheral rim enhancement. b T1 weighted coronal (pre-contrast); mixed intensity lesion with predominantly high T1W signal centrally. c T1 weighted coronal (post-contrast); mixed intensity lesion with predominantly high T1W signal centrally. The peripheral rim enhancement is easily appreciated in this image. d T2 weighted coronal; mixed intensities within the lesion, suggestive of the presence of both solid and cystic components

Fig. 3

a Representative T1W MR image of case (1) the T1W hyperintense sellar lesion is noted. b Representative T1W MR image of case (2) the lesion exhibits T1W hyperintensity, with a degree of heterogeneous signal centrally. c Representative T1W MR image of case (3) this lesion exhibits T1W iso- to- hypointensity, with prominent peripheral contrast enhancement. d Representative T1W MR image of case (4) this lesion exhibits T1W hypointensity, with prominent peripheral contrast enhancement. e Representative T1W MR image of case (5) this lesion exhibits T1W hyperintensity, with subtle contrast enhancement and central heterogeneous signal. f Representative T1W MR images of case (6) the sellar lesion demonstrates heterogeneous signal centrally, with a peripheral rim of contrast enhancement. The satellite lesion adjacent to the sella on the left-hand side exhibits similar signal characteristics