O-02 Inactivation of KDM1A with the concurrent presence of MGUS in a patient with GIP-dependent Cushing's syndrome and the vanishing effect of octreotide therapy

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Abstract Introduction Glucose-dependent insulinotropic peptide (GIP)-dependent primary bilateral macronodular adrenal hyperplasia (PBMAH) is a rare cause of Cushing's syndrome. It has germline genetic predisposition and requires for personalized approaches to investigation and therapy. We aimed to present the rare case of a GIP-dependent PBMAH patient with unusually severe cortisol secretion and a KDM1A inactivation with an accompanying haematological co-morbidity related to that mutation. Clinical Case A 41-year-old woman presented with a 5-kg weight gain in last 6 months, irritability and fatique. Physical examination revealed elevated blood pressure, increased supraclavicular fat pads, and abdominal obesity. The cortisol level was 25.9 (6.7-22.6) µg/dL in the morning, 16.9 µg/dL in the late night, and 6.5 µg/dL in the morning after an overnight 1 mg of dexamethasone. Urinary free cortisol (UFC) level was also elevated to 2150 (58-403) µg/24-h. The early morning plasma ACTH level was 1.5 (7-63) pg/mL. Abdominal imaging revealed 29×23 mm adenomas on the right and 46×35 mm on the left with high fat content. Cortisol was stimulated by the administration of mixed meals (+537%) but not by TRH, GnRH, metoclopramide or upright posture. The response to mixed meals was blunted by pretreatment with subcutaneous 100 mg octreotide. Following the patient's diagnosis of GIP-dependent PBMAH, octreotide LAR therapy was initiated. Although inducing a significant acute suppression of UFC and improvement in symptoms during the first 3 months, the UFC began to rise due to the resistance in the following period (Figure 1). After 9 months of octreotide LAR treatment, left adrenalectomy was performed according to the adrenal volumetric assessment. Histopathology was reported as diffuse macronodular adrenal hyperplasia without internodular atrophy. Even though the patient had a unilateral adrenalectomy, adrenal insufficiency occurred in the postoperative period. Subsequently, the patient has been closely monitored and followed up with a physiological, divided-dose hydrocortisone replacement regimen for 7 months. A germline heterozygous variant in the KDM1A gene in the patient's blood sample and a recurrent deletion in the short p arm of chromosome 1 harboring the KDM1A locus in the adrenal sample were identified. When screened for diseases associated with the KDM1A mutation, monoclonal gammopathy of undetermined significance (MGUS) was detected in the patient with mild anemia, and genetic counseling was also provided. Conclusion The management of GIP-dependent PBMAH remains controversial, and further therapeutic options are under investigation. Due to the very limited number of case reports and the heterogeneous nature of the disease, special features of our case, which are severe cortisol excess, accompanying MGUS, the vanishing effect of octreotide, and adrenal insufficiency after unilateral adrenalectomy, might contribute to the existing literature.Figure 1.Urinary free cortisol levels following octreotide therapyUFC: Urinary free cortisol, ULN: Upper limit normal, LAR: Long acting release

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