Practical use of the new 2017 who classification of silent pituitary adenoma; retrospective analysis in single centre

Objective: To analyze the pathological and clinical features of silent pituitary adenoma (SPA) under the new 2017 World Health Organization(WHO) Classification of Tumors of Endocrine Organ, and to provide relevant experience for the clinical diagnosis and treatment of SPA. Methods: Under the new 2017 WHO Classification of Tumors of Endocrine Organ, histopathological features of silent pituitary adenoma were evaluated between 2018 and 2019 in single centre. Results: The medical records including radiological and histopathological reports of 220 patients (55.9% female, mean age 55.25±11.12 years) were retrospectively analyzed. Patients with visual field impairment, headache, and oculomotor palsy accounted for 59.5%, 37.7%, and 4.1%, respectively.9.5% of patients have evidence of apoplexy, the average maximum diameter of the tumor is 29.0±9.8mm, and the proportion of giant adenoma is 11.81%. The most common type of tumor is 107 cases of silent gonadotroph adenoma, followed by silent corticotroph adenoma 74 cases，23 cases of null cell adenoma. Null cell adenoma is more invasive and Ki-67 index is higher (P<0.05). Three types of high-risk adenoma were identified, with 74 cases of silent corticotroph adenoma accounting for the highest proportion, followed by 4 cases of sparsely granulated somatotroph adenoma and 3 cases of PIT1-Positive Plurihormonal Adenomas. High-risk pituitary adenoma is higher than low-risk pituitary adenoma in invasive，recurrence and apoplexy (P<0.05). Invasive pituitary adenoma Ki-67 was significantly higher than non-invasive pituitary adenoma (P<0.001).The invasive of recurrent pituitary adenoma was higher than that of non-recurrent pituitary adenoma (P<0.05). Conclusion: The new version of the classification is very practical. Silent gonadotroph adenoma is the most common silent pituitary adenoma. High-risk pituitary adenoma, recurrent pituitary adenoma, and null cell adenoma have higher invasiveness and Ki-67 index.