A Comprehensive Study of Spindle Cell Oncocytoma of the Pituitary Gland: Series of 6 Cases and Meta-Analysis of 85 Cases

OBJECTIVE: To discuss optimal treatment strategy for spindle cell oncocytoma (SCO) of the pituitary gland. METHODS: Institutional cases were retrospectively reviewed. A systematic literature search and subsequent quantitative synthesis were performed for further analysis. The detailed features were summarized and the tumor control rate (TCR) was calculated. RESULTS: Eighty-five patients (6 institutional and 79 literature) were included. The annual incidence was approximately 0.01e0.03/100,000. The mean age was 56 years. Vision loss was present in 60%. Seventy-three percent showed hormonal abnormalities. On magnetic resonance imaging, tumor was avidly enhancing, and the normal gland was commonly displaced anterosuperiorly. Evidence of hypervascularity was seen in 77%. Gross total resection (GTR) was achieved in only 24% because of its hypervascular, fibrous, and adhesive nature. The mean postoperative follow-up was 3.3 years for institutional cases and 2.3 years for the integrated cohort. The TCR was significantly better after GTR (5-year TCR, 75%; P = 0.012) and marginally better after non-GTR D upfront radiotherapy (5-year TCR, 76%; P = 0.103) than after non-GTR alone (5-year TCR, 24%). The TCRs for those with low Ki67 index (<= 5%) were marginally better than those with higher Ki-67 index (5-year rate, 57% vs. 23%; P = 0.110). CONCLUSIONS: Frequent endocrine-related symptoms, hypervascular signs, and anterosuperior displacement of the gland support preoperative diagnosis of SCO. GTR seems to have better long-term tumor control, whereas the fibrous, hypervascular, and adhesive nature of SCO makes it difficult to achieve GTR. In patients with non-GTR, radiotherapy may help decrease tumor progression.

Automated summary

This study reviewed 85 cases of SCO and found that patients had an average age of 56 years, 60% had vision loss, and 73% showed hormonal abnormalities. The tumor was avidly enhancing on MRI images, and GTR had a higher tumor control rate postoperatively, while patients with low Ki67 index had better prognosis.