SAT-080 An Atypical Adenoma Presenting with Hyperandrogenism: A Rare Case Presentation on a Pituitary Germ Cell Tumor

Abstract Disclosure: D.H. Tran: None. C. Pham: None. J.D. Carmichael: None. G. Zada: None. J. Sisti: None. D. Ashouri: None. C.T. Nguyen: None. Background: Mixed germ cell tumors (GCT) are a rarely reported etiology for pituitary masses. Clinical Case: An 18-year-old-male with no medical history and normal pubertal development presented with one year of progressive bilateral vision loss and persistent headaches. MRI demonstrated 33x18x30 mm macroadenoma with optic chiasm compression. He reported gynecomastia, galactorrhea, frontal hair loss, weight gain, fatigue, and coarsening skin. He denied loss of libido, excessive thirst, polyuria, or illicit androgen use. Initial lab results demonstrated total testosterone 805 ng/dL (249-836), free testosterone 39.55 ng/dL (8.30-25.70), FSH 0.56 mIU/mL (1.4-18.1), LH <0.07 mIU/mL (<6.00), prolactin 63.77 ng/mL (2.17-17.7), AM cortisol 1.69 mcg/dL (5.27-22.45), free T4 0.53 ng/dL (0.89-1.76), and TSH 0.13 mIU/L (0.55-4.78). Physical exam revealed male pattern baldness, acne, bilateral gynecomastia, and Tanner stage V genital development without atrophic testes (estimated 15-20 cc) concerning for hyperandrogenism. Patient underwent resection of the pituitary mass. Post-operative course was complicated by arginine vasopressin deficiency (AVP-D). Pathology demonstrated a pleomorphic and cystic mixed GCT (70% teratoma, 25% seminoma, 5% choriocarcinoma), with human chorionic gonadotropin (hCG) 28.9 mIU/mL (<5), alpha fetoprotein (AFP) <1.8 ng/mL (<8.3), and alkaline phosphatase (ALP) 76U/L (46-169). Immunohistochemistry findings showed Sal-like protein 4 (SALL4) expression of the seminomatous and choriocarcinoma components and octamer 4 (OCT4) of the seminomatous components, which are highly specific markers for seminomas. The patient was discharged home on hormonal replacement and referred to oncology for further therapies. Conclusion: This case highlights a rare manifestation of mixed GCT of the pituitary with hyperandrogenism. GCTs can be divided into germinomas or non-germinomas and mostly present in males with a higher incidence in Asians. More than half present in the first decade of life with a median age of 16. Many patients experience precocious puberty and rapid vision loss with associated AVP-D. Associated markers include elevated HCG, AFP, and placental ALP in germinomas. First line treatment includes radiotherapy with adjuvant treatment including platinum-based chemotherapy regimens. This case highlights how careful physical examination and interpretation of endocrine hormones can help elucidate the source of hormonal dysfunction, and that atypical findings should prompt further evaluation and a broad differential diagnosis. Presentation: Saturday, July 12, 2025