Endocrine Abstracts

Introduction: Acromegaly is a rare pathological condition characterized by excessive growth hormone (GH) secretion, leading to elevated levels of insulin-like growth factor 1 (IGF-1). According to the 2022 World Health Organization classification, GH-secreting pituitary adenomas fall under the PIT1-lineage. Pure GH-secreting adenomas selectively release growth hormone and may exhibit dense or sparse granulation patterns. Other subtypes include mammosomatotroph adenomas, mature plurihormonal adenomas, immature plurihormonal adenomas, and acidophil stem-cell adenomas, all expressing multiple hormones. Immature PIT1-lineage tumors consist of immature cells expressing PIT1 but lack morphologic and immunohistochemical features of fully differentiated cells.

Case report: A 50-year-old male patient reported a chief complaint of escalating joint pain over the past four years. A comprehensive examination revealed distinctive features indicative of acromegaly, including an enlarged nose, prominent forehead, jaw prognathism, widened tooth gap, enlargement of hands, and increase in foot size. The patient’s tests IGF-1: 1150 ng/ml (N:76,7-203) GH:5,1 ng/ml (N:0.03-2,47) was detected. Other hormone profiles were normal. During the OGTT test, the values at 60th minute glucose:224,3 mg/dl GH:37.5 ng/ml were pathological. Pituitary MR imaging showed an adenoma with a diameter of approximately 1.8 cm in the left half of the pituitary gland extending to the cavernous sinus and inferior optic chiasm. The visual field test was normal. Transsphenoidal endoscopic pituitary surgery was performed and immunohistochemical findings on pathology were as follows; chromogranin:+, PIT-1:+, SF-1:-, GATA-3:-, Estrogen receptor:-, GH: diffuse+, Prolactin: diffuse+, TSH:-, ACTH:-, LH:-, FSH:-, NKX2.2:-, SSTR2A: Sparse cell +, Ki-67:5%, PHH3:6 mitoses/10 large magnification area, PAS:-. Histomorphologic and immunohistochemical findings were consistent with an immature PIT-1-origin adenoma. In the 3rd postoperative month; IGF-1: 326 mg/ml (N:76.7-203) GH: 0.54 ng/ml (N:0.03-2,47), 75 g OGTT test; 30. min glucose:145 mg/dl GH:0.7 ng/ml was detected. Control pituitary MRI showed no residual and recurrence.

Discussion: Immature PIT1-lineage tumors, displaying lower differentiation levels, present with a variable clinical profile, with approximately 10–20% of affected patients exhibiting GH excess. TSH overproduction is more common, hyperprolactinemia is often attributed to direct tumor secretion. Imaging consistently reveals these as large, invasive tumors, requiring multiple surgeries, radiation, and systemic therapies due to their aggressive nature. In the light of all this information, which class of acromegaly the patient is in may give us crucial clues for the clinical prognosis.