Endocrine Abstracts

Background: Mammosomatotroph cell adenoma is rare, accounting for fewer than 2% of all pituitary adenomas and about 8% of tumors associated with acromegaly. A variety of adenomas may present with clinical signs and symptoms of GH hypersecretion including pure GH cell adenomas, mixed GH and prolactin cell adenomas, and monomorphous adenomas with primitive cells able to secrete GH and prolactin including the acidophilic stem cell adenoma and the mammosomatotroph cell adenoma. Here we present a patient with pituitary macroadenoma discovered three years ago with elevated Insulin Growth Factor-1 (IGF-1) but no clinical features of acromegaly.

Clinical presentation: A 35-year-old Caucasian nulliparous woman, known case of pituitary macroadenoma with a recent onset of hypertension presented to the clinic for routine check-up. Her initial presentation was of irregular menstruation, labs revealed high PRL and MRI confirmed pituitary macroadenoma in the year 2019. MRI′s at the time of diagnosis and further follow-ups were compared, despite the use of cabergoline the tumor size did not reduce; Hence she was evaluated for NFPA. Endocrinological workup for our patient revealed Ft4 1.10(1-2 ng/dl), prolactin 18(6 - 29.9 ng/ml), cortisol 10.3(3.7-19.4 mg/dl), OGTT values were 114/144, Hba1c 5.5, serum IGF-1 levels of 721(63.4-223.0 ng/ml), Growth hormone suppression test revealed 1 h GH of 12 ng/ml. Over the three years pituitary MRI′s were done each year and size in first, second and third MRI are 1.2X1.3X1.2 cm,1.2X1.3X 1.1 cm and 1.2X1.1X0.95 cm respectively. There was no reduction in tumor size over the past 3 years. Her serum IGF-1 levels were 3 times the normal upper limit. GH suppression test confirmed somatotroph adenoma with no symptoms of acromegaly. With these results, cabergoline was stopped, patient was advised for pituitary surgery.

Conclusion: In conclusion, the clinical spectrum of acromegaly varies from florid to subtle/no features and the diagnosis may be missed in some patients who are presumed to have clinically nonfunctioning pituitary tumors or no pituitary disorder. IGF-1 and GH should be checked in all patients of pituitary macroadenomas irrespective of initial symptoms as clinical features may take time to evolve. This recognition expands the therapeutic options to include pharmacological treatment and also provides a tumor marker to monitor the efficacy of treatment.