Based on tumor immunoreactivity profile and assigned clonality, MPA should be classified into three main patterns (9): (1) GH-PRL-TSH-secreting adenomas combined with FSH-LH-secreting tumors; (2) GH-PRL-TSH producing adenomas combined with ACTH-secreting tumors; and (3) ACTH-secreting adenomas combined with FSH-LH-producing tumors, with the first two subgroups being identified as the most prevalent ones (Table 3). This evidence concerns the gene PLOD1 and adenoma.