SAT-468 Conversion of a Non-Secreting to a Growth Hormone-Secreting Pituitary Adenoma: A Case of Rapid Development of Acromegaly

Introduction: Acromegaly is known to have a slow and insidious course. As a result, the diagnosis is made very late, and at the time of diagnosis most patients have macroadenomas. The average interval from onset of symptoms of acromegaly and diagnosis is approximately 12 years. In addition, conversion of a non-functioning to a functioning pituitary adenoma is very rare. We report a case of a documented non-secreting pituitary macroadenoma turning into a growth hormone secreting one resulting in symptomatic acromegaly in less than 4 years. Clinical Case: A 28 year old African American female presented for evaluation of headaches in 2014. Her past medical history is significant for headaches and childhood epilepsy since age 9. During her workup she was found to have a 1.2 cm pituitary macroadenoma on MRI. Her review of systems showed no evidence of vision changes, galactorrhea, hand enlargement, weakness, changes in body weight or skin pigmentation. Her exam was unremarkable, in particular she did not have any acromegaloid or cushingoid features. Her pituitary hormone work-up was unremarkable, showing no evidence of hormone excess or deficiency. Her IGF-1 was found to be 251 ng/dL (Normal: 78-270). She was evaluated by neurosurgery at that time, who recommended conservative approach with serial follow-up imaging. About 3 years and 8 months later, she was admitted to the hospital for her worsening symptoms of headaches, which were noted approximately 3 times weekly. On further questioning, examination and comparison with old pictures, she was noted to have coarsening of her facial features as well as increase in her ring size. Laboratory tests showed elevated IGF-1 levels on 2 separate occasions at 570 and 551 ng/dL. On repeat imaging, the pituitary macroadenoma was noted to be increased in size to 1.8 cm with increasing suprasellar extension and abutting the anterior aspect of the optic chiasm. She underwent endoscopic excision of pituitary adenoma and reconstruction of sellar floor. The pathology came back positive for human growth hormone staining. IGF-1 level decreased to 244 ng/mL in less than 4 months after surgery. Conclusion: Conversion of non-secreting pituitary adenoma to a growth hormone secreting one can happen over a relatively short time span, resulting in symptomatic acromegaly. We had a unique opportunity to observe this since the patient had previous imaging and biochemical work-up which we could use for comparison. This is contrary to the classic description of acromegaly where the clinical picture develops very slowly over many years or even decades.