MON-507 A rare case of high grade carcinoma presenting as unilateral adrenal metastasis with PTH related Peptide hypercalcemia and possible ectopic ACTH secretion

Abstract Disclosure: S.R. Bogi: None. J. Khan: None. V. Manucha: None. V. Wright: None. V. Garla: None. Adrenal metastases can be commonly seen in primary solid tumors like lung (42%), breast (58%), melanoma (50%) and gastrointestinal (GI) (10-16%). However, metastatic adrenal tumor as their primary presentation is uncommon. In addition, coexistence of two paraneoplastic endocrine syndromes is rare. We present a case with both these entities. 61 year old incarcerated male with HIV on genvoya, treated syphilis, diabetes mellitus type 2, left nephrectomy for donation presented as a transfer from outside hospital for adrenal mass. He reported unintentional weight loss, fever and night sweats since several weeks and had failed multiple courses of antibiotics for suspected pneumonia. Outside imaging showed necrotic appearing right lung mass and 9.3 cm right adrenal mass with right adrenal vein thrombosis. Hormonal work up for adrenal mass ruled out pheochromocytoma and primary aldosteronism. DHEAS was normal. However, ACTH was significantly elevated at 300 pg/ml, 1 mg dexamethasone suppression test with 8am cortisol of 16.75 mcg/ml and elevated 24 urine free cortisol at 172 mcg raising concern for ectopic ACTH secretion. His vitals however were stable with normal potassium levels. His calcium was elevated at 14.1 mg/dl, PTH suppressed at 7.2 pg/ml. Further lab work revealed PTH related peptide (PTHrP) significantly elevated at 163 ng/ml, low 25-OH vitamin D and normal 1,25-OH vitamin D supporting PTHrP mediated hypercalcemia. The necrotic lung mass was favored to be malignant after infectious work up ruled out abscess as the etiology. Bronchoscopy revealed no visible mass; trans-bronchial biopsy was negative for malignancy but biopsy from mediastinal lymph nodes was positive for metastatic carcinoma. Interventional radiology was unable to obtain lung biopsy. They proceeded with right adrenal mass biopsy which showed metastatic poorly differentiated high-grade carcinoma of suspected pulmonary, GI or pancreatobiliary origin on staining. ACTH staining remains in process. Further work up for primary tumor with esophagogastroduodenoscopy, colonoscopy, endoscopic ultrasound of pancreas was unrevealing. He developed recurring right pleural effusion needing catheter placement; pleural fluid cytology was also positive for metastatic high-grade carcinoma. Unfortunately, he quickly deteriorated and chose comfort measures and deceased within four weeks of presentation. Poorly differentiated high-grade carcinoma presenting as isolated adrenal metastatic tumor is rare (∼1%) and can pose significant challenge to treat. Paraneoplastic syndromes (PNS) with overall prevalence of 8%, can present at different stages of malignant neoplasms. PTHrP mediated hypercalcemia accounts for 90% of hypercalcemia in malignancy, usually presents in late stages of cancer and carries poor prognosis with mean survival of 4 to 6 months. Presence of PNS at advanced stages can be indicative of poor prognosis. Presentation: Monday, July 14, 2025