12568 “Unusual Presentation Of Pituitary Macroadenoma: Co-secretion Of GH And Prolactin With Prozone Phenomenon"

Abstract Disclosure: F. Lopez Maldonado: None. A. Rodriguez Gonzalez: None. A. Mayorga Leon: None. E. Leon Milan: None. Background: Plurihormonal pituitary adenomas (10-15% cases) are linked to acromegaly, especially in young patients. ∼8% are associated with MEN1. They produce growth hormone (GH), prolactin (PRL), and sometimes thyroid-stimulating hormone (TSH), causing clinical effects from GH and excess PRL. Most are large and invasive in ∼50% of cases. Case Report: A 37-year-old male with no significant medical history, exhibited monthly right temporal headaches, ipsilateral eye pain, nausea, and vomiting, that responded to analgesics and antibiotics. Two years later he presented increased headaches, fainting, and decreased vision in the right eye. Over the next four years, his headaches worsened, leading to complete vision loss in the right eye and compromised vision in the left eye. Evaluation by Internal Medicine revealed bradylalia, recent memory changes, a prominent supraorbital arch, pale optic disc with centered vessels in the right eye. Additionally, macroglossia, prognathism, and acromegaly-like changes in extremities were noted. Campimetry revealed left temporal hemianopsia. Hormonal profile: LH 0.04 mIU/mL (1.24 - 8.6 mIU/mL), FSH 0.21 mIU/mL (1.27 - 19.2 mIU/mL), TSH 4.78 mIU/mL (1.24 - 19.2 mIU/mL), Total T4 2.04 mcg/dL (4.5 - 10.9 mcg/dL), PRL 1.1 ng/mL (2.8 - 13.13 ng/mL) (at dilution 1:100) >20,000 ng/mL, Cortisol 0.903 mcg/dL (3.7 - 19.4 mcg/dL), IGF-1 1001 ng/mL (41 - 246 ng/mL), GH 12 ng/mL (0.03 - 2.47 ng/mL), Total Testosterone 0.13 ng/mL (1.6 - 8.7 ng/mL) MRI report: Invasive macroadenoma measuring 49x43x48 mm with partial inclusion of the right cavernous sinus and complete inclusion of the left cavernous sinus, bilateral carotid involvement with left predominance, involvement over the optic chiasm, pituitary stalk, floor of the sella turcica with migration towards the sphenoidal sinus. Diagnosis: Co-secreting PRL and GH pituitary macroadenoma, Secondary Hypogonadotropic Hypogonadism, Secondary Hypothyroidism, Secondary Adrenal Insufficiency. Treatment: Prednisone 5 mg PO QD, Cabergoline 0.5 mg PO QD 5/7 (MWFSS), Levothyroxine 100 mcg PO QD, Sostenon 240 mg/mL IM every 3 weeks. One week post-treatment initiation, the patient reported improvement.Follow-up labs showed normalized hormone levels. MRI revealed a 37x34x28 mm pituitary macroadenoma with bleeding and cystic changes. Surgery was deferred due to the favorable response to medical treatment. An annual MRI was performed, which showed a decrease in tumor size. By the seventh year, the tumor had reduced by 98% under the same treatment. Conclusion: Macroprolactinomas pose diagnostic challenges due to the prozone effect, requiring sample dilution for accurate diagnosis. Reflecting on the unexpected, this tumor co-secretes GH, which is uncommon; however, it responded effectively to medical treatment. Presentation: 6/3/2024