GH1 and familial isolated pituitary adenoma: Based on the WHO 2017 classification (available in 17 cases), the most common subtype of GH-secreting PA was the densely granulated somatotroph adenoma (8/17), followed by sparsely granulated somatotroph adenoma (5/17) and mixed somatotroph-lactotroph adenoma (4/17) (Fig. 1).