Endocrine Abstracts

62-year-old woman was an employee of catering service. She had progressive limb weakness, easpecially proximal part since May, 2015, with diurnal change. She had difficulties in lifting arms, holding plates steady, and knee buckling while walking, which made her quit the job. Generalized myasthenia gravis (MG) was confirmed by positive acetylcholine receptor antibody (12.8 nmol/l) and marked decremental changes in repetitive stimulation test in November, 2015. Her limb weakness was much improved under pyridostigmine treatment. Chest CT scan revealed no thymoma, but thyroid nodules were incidentally found. Thyroid function test was normal. Thyroid ultrasound showed bilateral multinodular goiter, and fine needle aspiration cytology showed negative for malignant cells. Otherwise, persistent elevation of serum IgG4 (214–249 mg/dl) was incidentally noted since May, 2016. She had dry mouth and dry eyes, but denied pancreatitis or mass lesions. Laboratory evaluation showed elevated ESR (27 mm/1-hr), positive of anti-ENA antibody (Ab) and anti-SS-A (8.028 U/mL), but negative of other auto-antibodies (anti-TPO, TA, ANA, anti-SS-B/dsDNA/SM/RNP/SCL-70/CENP/Jo-1/Ribosomal-P). She started hydroxychloroquine and pilocarpine treatment for Sicca syndrome. In November, 2019, thickened lips and widened teeth space were noted, but she denied enlarged fingers or feet, enlarged tongue, snoring, or arthralgia. Blood test showed high serum IGF-1 (588 ng/ml) and hGH (8.19 ng/ml). 75g OGTT showed paradoxical response and non-suppressible of GH (nadir 9.47 ng/ml) after glucose loading, and acromegaly was confirmed. Sella MRI revealed a 1.0 cm well-defined, non-enhancing nodule at left aspect of pituitary gland. She received endoscopic transnasal transsphenoidal adenomectomy on 2020/12/30. Serum GH level on post-operative day 1 decreased to 2.2 ng/ml. She reported subjectively better feeling with less limb weakness after surgery. Follow-up laboratory test in January, 2020 showed normal thyroid and adrenal function, and slightly decreased serum IgG4 levels (200 mg/dl). MG is a chronic autoimmune neuromuscular disease. Patients with MG usually have a higher incidence of other autoimmune disorders. The association between acromegaly and MG is extremely rare. There were only two cases of GH-secreting adenoma in MG patients reported. There was no report of association between acromegaly and other autoimmune disorders, such as sicca syndrome or IgG4-related disease, except one study reported higher thyroid autoimmunity in acromegaly patients than normal population. However, the identification of anti-pituitary antibodies in patients with acromegaly and other types of pituitary adenomas in some studies may suggest a possible involvement of autoimmunity in pituitary tumorigenesis.