Endocrine Abstracts

Introduction: Somatotropinomas are typically recognized when GH excessively secretion causes acromegaly. «Silent» somatotroph adenomas (immunohistochemical evidence of GH excess without biochemical or clinical evidence) and «clinically silent» somatotroph adenomas (immunohistochemical and biochemical evidence without clinical evidence) have occasionally been reported. The relative frequency of each presentation is unknown.

The aim is to describe the clinical course of a patient with clinically silent somatotroph adenoma.

Case presentation: In a female patient disease presented at the age of 22 years with oligomenorrhea and hyperprolactinemia – PRL 881.37 mU/l (127–637) for which she received cabergoline 0.25 mg per week with induction of normoprolactinemia and normalization of menstrual cycle. Within a year MRI revealed endo-suprasellar pituitary adenoma 16×15×13 mm, without chiasm compression. The levels of TSH, cortisol, LH, FSH, prolactin were in normal ranges. These changes were regarded as nonfunctioning pituitary adenoma and annual follow-up was recommended. Subsequent MRIs showed an enlargement (21×18×17 mm), mainly due to suprasellar component without chiasm involvement. ACTH, cortisol, PRL, LH, FSH were within reference ranges and a decrease of free T4 8.1 pmol/l (9–20) and IGF-1 elevation 816.9 ng/ml (128–315) were noted. The high fasting GH levels confirmed biochemical acromegaly as at physical examination there were no clinical signs of this disease. Transsphenoidal surgery was performed and immunohistochemical staining showed that tumor cells were strongly reactive to GH and relatively mildly reactive to PRL, with ki-67 2% confirming the presence of clinically «silent» somatotropinoma. After 3, 6, 12 months after the surgery the levels of IGF-1 remain in normal ranges. The brain MRI was repeated after 12 months thereafter with no signs of adenoma.

Conclusion: This case demonstrates the need to perform an extensive hormonal testing for all patients with presumably non-active pituitary adenoma.