Gamma knife radiosurgery for pituitary spindle cell oncocytomas

Spindle cell oncocytomas (SCOs) are benign lesions of the posterior portion of the pituitary gland that typically come to neurosurgical attention due to compression of the sellar or parasellar structures, and headaches. Initial treatment options for SCOs include surgical resection, particularly via the transsphenoidal approach. However, given that initial resection tends to be insufficient and subsequent revision surgery carries high complication risk, adjuvant treatment modalities may appear to offer promising solutions for controlling tumor progression. This report focuses on a potential new therapeutic option for SCOs, gamma knife radiosurgery (GKRS).

The authors identified all patients at one center who had a pituitary lesion treated with GKRS between 2005 and 2016. Five patients with histopathologically confirmed SCO who underwent GKRS were retrospectively identified and included in the present study RESULTS: The mean patient age was 52 years (range, 41-61 years). The most common presenting symptom was visual disturbance. All five patients had a history of transsphenoidal surgical resection prior to GKRS therapy. The mean tumor volume was 2.25 cm³ (range 0.7-5.38 cm³). The median tumor margin dose was 12 Gy (range, 12-14 Gy), and the median maximal dose was 24 Gy (range, 24-35 Gy). The median isodose was 50 (range, 40-50). No tumor volume progression was observed during radiological follow-up after GKRS (mean, 52 months; range, 36-84 months). At last follow-up, no neurological, endocrinological, or visual complications had been observed.

Given their highly vascular and adherent nature, SCOs can be challenging tumors to treat, in particular when they recur. In our five cases, GKRS provided excellent tumor volume control for approximately 4.3 years on average. These results suggest that GKRS is a safe and effective treatment modality for histopathologically confirmed residual SCO.