MON-075 Invasive Breast Carcinoma in Individual with Genotype Negative MEN-1, Pituitary Macroadenoma with high IGF-1, and Adrenal Nodule - Implications for Management

Abstract Disclosure: B. Zaidi: None. M. Javid: None. B. Williams: None. S.L. Mokshagundam: None. Background: Invasive ductal adenocarcinoma is the most common type of breast cancer. Recent studies, through a better characterization of the functions of the menin protein, have started to demonstrate how changes in this protein may be related to breast cancer. IGF-1 system is known to modulate growth of mammary epithelial cells. But, the relation to breast cancer is complex and needs better understanding. Clinical Case: A 60 year old Caucasian female had screening mammogram in May 2024 that showed new 2.0cm mass in inferior aspect of right breast. A diagnostic mammogram showed a 1.8cm right breast mass. A right breast biopsy showed invasive ductal adenocarcinoma, G3, ER+, PR+, HER2 1+. She was noted on exam to have a right axillary lymph node. A biopsy of the lymph node revealed metastatic poorly differentiated breast carcinoma. She was started on neoadjuvant chemotherapy with Adriamycin, Cyclophosphamide, and Paclitaxel. Later Pembrolizumab was added. In August 2024 staging scans raised concern for bilateral adrenal metastases. CT Abdomen adrenal protocol showed a 3 x 2.0 cm right adrenal nodule and two left adrenal nodules both measuring up to 2.2 cm all demonstrate non-contrast attenuation <10 HU and enhancement characteristics (absolute washout > 60%) compatible with benign lipid rich adenomas. In October 2024 during routine follow-up complained of dizziness. A CT of head showed an enhancing pituitary mass. She was then seen in Endocrine Clinic. She reported that she had pituitary surgery in 1996 but had not followed up in more than 25 years. Details of surgery and pathology were unclear. Two years ago she had left inferior parathyroidectomy for primary hyperparathyroidism at a local hospital. Blood tests when seen in Endocrine Clinic showed IGF-1 level of 825 ng/mL. prolactin was 6.9 ng/mL and LH and FSH were low. Rest of pituitary functions were normal. Serum calcium was elevated at 10 mg/dL and PTH was also elevated at 137 pg/mL. Invitae genetic testing for MEN-1 was negative. Pituitary MRI showed a fairly large sellar based mass with suprasellar extension compressing the optic chiasm with mass effect on the hypothalamus with findings suggesting possible cavernous sinus involvement on the left but no invasion of the sphenoid sinus or clivus. mg/dL and PTH was also elevated at 137 pg/mL. Thyroid ultrasound exam showed a 1.0 CM hypoechoic nodule posterior to left thyroid lobe which could be a parathyroid adenoma. The overall clinical picture was consistent with genotype negative MEN-1. She underwent right mastectomy and axillary lymph node dissection in January 2025. Discussion: This case raises important questions related to the role of IGF-1 in breast cancer, potential need for intervention in improving outcomes and also the role of early screening for breast cancer in individuals with MEN-1. These will be discussed. Presentation: Monday, July 14, 2025