SAT-070 A case series of aggressive pituitary tumors ( PitNets), When should metastatic disease be suspected?

Abstract Disclosure: S.K. Azad: None. T. Aggarwal: None. A.T. Drincic: None. Background: Classically aggressive PitNETs have been described based on radiological, clinical and pathologic criteria including: rapidly growing/or large tumor, invasiveness (cavernous sinus, bones, nasal mucosa) with high cell proliferation (Ki67>3% & P53 +), refractoriness to standard treatment and recurrence or progression. Given the rarity of aggressive Pit/NETs fundamental challenge clinicians face is consideration of searching for systemic disease.Here we describe 3 different cases of aggressive Pit/NETs and explore their clinical characteristics. Case series: 1. A 48 y/o female presented with CNIII palsy and was diagnosed with silent ACTH producing pituitary adenoma. She underwent TSS x 2 & STR x 2 (Ki67 8-12%) and was in remission of almost 2 years, until she developed clinically relevant Cushing’s disease associated with cortisol related psychosis and tripling of her biochemical markers. MRI was noted stable leading to work up for metastatic disease and was eventually diagnosed with metastasis to liver and C1 vertebrae.2. A 33 y/o F who was diagnosed with mixed GH and lactotroph secreting adenoma of 2.2 cm. Patient was in complete remission after being on cabergoline followed by subtotal resection (Ki67 8.6%) and radiation therapy. However she then developed elevated IGF-1, GH and abnormal OGTT with stable MRI prompting further evaluation. She was also diagnosed with metastatic Pit/NET to lungs and a paratracheal mass. 3. A 64 y/o M with 4 cm FPA causing Cushing’s disease s/p TSS x 3, salvage RT which was aggressive Ki67 ∼ 8%. Patient continued to have stable disease until MRI showed progression with concordant ACTH levels elevated. He underwent 3rd surgery & his Ki67 had risen to 30-40% with less ACTH staining (partial sparse granularity) and loss of expression of GH, Prolactin, TSH. Even though Ki67 was higher, no metastatic disease was demonstrated on further work up. Discussion: These cases demonstrate that discordance between biochemical and radiological evaluation should prompt early evaluation to look for systemic disease. Although our 3rd case did have radiological as well as biochemical concordance with aggressive tumor based on elevation of Ki67 (40%), no metastatic disease was found. This is in accordance to European society of Endocrinology recommendation for diagnosis of aggressive pituitary tumors who also recommend considering evaluation of metastatic disease if site specific symptoms, radiologically invasive tumor with clinically relevant rapid tumor growth or discordance between biochemical and radiological findings are noted. Presentation: Saturday, July 12, 2025