GH1 and growth hormone-producing pituitary gland adenoma: The tumors correspond to thirteen different adenoma subtypes (including sparsely and densely granulated variants; Table 1) of which the largest group were diagnosed as prolactin cell adenomas (n = 32; 32.7 %) followed by: ACTH-cell adenomas (n = 28; 28.6 %), GH-cell adenomas (n = 14; 14.3 %), null-cell adenomas (n = 11; 11.2 %), mixed GH/Prolactin cell adenomas (n = 6; 6.1 %), FSH/LH-cell adenomas (n = 5; 5.1 %) and TSH-cell adenomas (n = 2; 2 %) 12 of these cases (12.1 %) were relapses.