ODP363 Growth hormone and prolactin co-secretion in acromegaly: a case study and review of the literature

Abstract

Abstract Introduction Growth hormone (GH) and prolactin co-secreting pituitary adenoma is the most common type of pleuri-hormonal adenomas. We present a case of GH and prolactin co-secreting macroadenoma with somato-mammotroph (SMT) histopathology. Case A 48-year-old female presented with complaints of chronic headaches and coarsening of facial features for >5 years. Associated symptoms included chronic fatigue, joint pain, heat intolerance, diaphoresis, and 20 lbs weight gain. She noted acral enlargement and ill-fitting dentures. She also reported snoring and witnessed apneic spells. She denied peripheral vision loss, galactorrhea, or breast tenderness. Past medical history included prediabetes, bilateral carpal tunnel surgery, and uterine ablation. On examination, her weight was 269 lbs, height 5'8", and BP 148/92 mmHg. She had acromegalic features including frontal bossing with coarse facial features, prominent jaw, and large hands with sausage-like fingers and sweaty palms. Her oropharynx was crowded with Mallampati grade 4. Laboratory data showed elevated IGF-1 level of 981 ng/mL (77- 220) and prolactin level – 189 ng/mL (4.8–23.3). The fasting GH level was 5.1 ng/mL (<7.1). Fasting blood sugar was 145 mg/ dl with an HbA1C of 6.4%. Repeat testing confirmed elevated IGF-1–803 ng/mL with a Z score of 4.5 and prolactin– 130.2 ng/mL. Prolactin levels were higher than expected for stalk effect, hence GH and prolactin co-secretion was suspected. The patient had secondary hypogonadism with normal cortisol and thyroid axes. MRI pituitary showed a 2.6×1.8×1.9 cm pituitary macroadenoma with erosion of sellar floor, extension into the right sphenoid sinus, and possible involvement of the left cavernous sinus. The patient underwent transsphenoidal hypophysectomy, which was complicated by transient diabetes insipidus. Postoperative GH levels remained elevated > 3ng/ mL (goal for remission < 1 ng/ ml). Surgical pathology showed SMT type pituitary adenoma, with tumor cells staining both for GH and prolactin. The patient will have repeat pituitary MRI and biochemical testing 2 months following surgery to assess the presence and extent of residual disease. Discussion The WHO's 2017 classification divides GH and prolactin co-secreting tumors to 1) SMT cell adenomas where monomorphous cells co-secrete both GH and prolactin; 2) mixed GH cell and prolactin cell adenomas, bimorphous tumors where 2 different cell types secrete GH and prolactin; and 3) acidophil cell tumors. SMT adenomas are morphologically similar to densely granulated adenomas. These are usually slow growing and rarely invade surrounding structures. They have low intensity on T2-weighted MR imaging. In a study of 94 acromegaly cases, SMT adenomas were the smallest in size, with minimal cavernous sinus invasion, and had a higher chance of complete tumor resection. In contrast, our patient had a relatively large and invasive SMT adenoma. Presentation: No date and time listed