Pituitary adenomas account for 15.9% of central nervous system tumors and can be divided into non-functional and functional adenomas depending on hormone secretion.1 Among the latter, pituitary prolactin (PRL) adenomas are the most common, accounting for approximately 32% to 66% of pituitary adenomas.2 This is followed by growth hormone (GH) adenomas with a pooled prevalence of 5.9 [95% confidence interval (CI): 4.4-7.9] per 100,000 persons, while the incidence rate was 0.38 (95% CI: 0.32-0.44) cases per 100 000 person-years.3 Thyroid stimulating hormone (TSH) adenomas account for 0.5% to 2% of all pituitary adenomas and have an estimated prevalence of 1 to 2 cases per million in the general population.4

A study conducted histologic examinations on 242 cases of pituitary GH adenomas, and immunohistochemistry showed that 45% were monohormonal and 55% were multihormonal, producing GH-PRL (77%), GH-TSH (13%), and GH-PRL-TSH (10%).5 A meta-analysis showed that 61% of TSH adenomas were monohormonal and 39% were multihormonal, with cosecretion of GH (57.5%) and PRL (41.4%).6 Compared to monosecretory pituitary adenomas, cosecretory pituitary adenomas show greater tumor recurrence and local aggressiveness and a significantly higher incidence of various cancers and cardiovascular complications.7

So far, studies of patients with pituitary GH adenomas who cosecrete TSH or PRL have rarely been reported, their clinical characteristics have been poorly elucidated, and available data on their diagnosis and treatment are limited. Therefore, to address this knowledge gap, we retrospectively collected the clinical data from patients diagnosed with cosecreting GH and TSH pituitary adenomas [(GH+TSH)oma] and cosecreting GH and PRL pituitary adenomas [(GH+PRL)oma] of Beijing Tiantan Hospital, Capital Medical University. Beijing Tiantan Hospital is one of the largest pituitary care centers in Asia. We also compared the clinical characteristics of 22 cases of (GH+TSH)oma and 10 cases of (GH+PRL)oma with 335 cases of solo-secreting GH pituitary adenoma (GHoma) and 49 cases of solo-secreting TSH pituitary adenoma (TSHoma). The aims of the study are (1) to explore the clinical characteristics of (GH+TSH)oma and (GH+PRL)oma and analyze their differences in preoperative hormone levels, imaging features, pathologic characteristics, and biochemical remission rates after treatment compared to GHoma and TSHoma and (2) to investigate the biochemical remission characteristics of (GH+TSH)oma and (GH+PRL)oma, analyze the risk factors leading to biochemical nonremission, and explore the clinical management of cosecreting pituitary GH adenoma.