SAT-108 - A Young Man With Pituitary Carcinoma: A Case Report

Introduction:
Pituitary neuroendocrine tumors (PitNETs) are typically benign adenomas that can be managed with surgery, medical therapy, or radiotherapy. Pituitary carcinomas—characterized by aggressive biological behavior and defined by an integrated clinico-pathologic framework—are exceedingly rare, accounting for approximately 0.2% of pituitary tumors. Sarcomatous transformation within PitNETs is even more uncommon and portends a highly malignant course.
Clinical

Case:
A 29-year-old man with a nonfunctioning PitNET diagnosed at age 20 underwent multiple transsphenoidal resections and adjuvant radiotherapy. Initially non-secreting, the tumor later evolved into a growth hormone–secreting phenotype (IGF-1 = 1,233 ng/mL). Despite 6 prior surgeries, temozolomide, and cisplatin–etoposide chemotherapy, the tumor progressed, ultimately measuring 5.9 × 3.6 × 3.4 cm with cavernous sinus and third ventricular invasion. Histopathology revealed a pituitary carcinoma with sarcomatous transformation, Ki-67 40–50%, and p53 50%. Next-generation sequencing identified ATRX and GNAS mutations. The patient was subsequently treated with octreotide LAR 20 mg every 28 days, bevacizumab 10 mg/kg every 2 weeks, and lomustine 90 mg/m² every 6 weeks, achieving a 25–50% radiologic reduction and decline in IGF-1 from 1,233 to 870 ng/mL after 3 months of therapy.

Conclusion:
This case illustrates an extraordinarily aggressive pituitary carcinoma with sarcomatous transformation, resistant to standard therapies yet partially responsive to a bevacizumab–lomustine regimen. To our knowledge, fewer than 15 similar cases have been reported since 1980. The coexistence of ATRX and GNAS mutations, transformation from a nonfunctioning to a secreting tumor, and partial therapeutic response highlight the biological complexity of these rare entities and underscore the importance of integrated histopathologic and clinical assessment in defining pituitary carcinoma.

Abbreviations:
PitNET: Pituitary Neuroendocrine tumor , TMZ: Temozolomide , TSSR: trans-sphenoidal surgery, IGF-1: Insulin Like Growth Factor-1

References
[1] O. M. Dekkers, N. Karavitaki, and A. M. Pereira, “Te epidemiology of aggressive pituitary tumors (and its challenges),” Reviews in Endocrine & Metabolic Disorders, vol. 21, no. 2, pp. 209–212, 2020.
[2] Asa SL, Mete O, Perry A, Osamura RY. Overview of the 2022 WHO classification of pituitary tumors. Endocr Pathol. 2022;33(1):6-26. https://doi.org/10.1007/s12022-022-09703-7
[3]. Raymond P, Raverot G, Ilie MD. Outcome and prognostic factors for pituitary carcinomas: lessons from a systematic review. Endocr Relat Cancer. 2023;30(5):e220338. https://doi.org/10.1530/ERC22-0338
[4]. Villa C. , Birtolo M. et al. Grading and Staging of pituitary neuroendocrine tumors. Brain Pathology 2025. DOI:10.1111/bpa.13299

*Unless otherwise noted, all abstracts presented at ENDO must not be released to the press or the public until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.*