PSAT023 Not Every Pain Is a Gain! A Rare Case of Adrenal Leiomyosarcoma.

INTRODUCTION: Adrenal leiomyosarcoma (AL) is a rare malignant tumor, representing only 0.1% to 0.2% of all retroperitoneal soft tissue sarcomas in adults (1). A young male's acute abdominal and back pain led to an unusual diagnosis of AL. CASE PRESENTATION: A 38-year-old male patient with no past medical history presented with a history of right sided abdominal pain of several months duration radiating to the back and significant weight loss. His vital signs were stable; however, he appeared mildly distressed and had tenderness on deep palpation in the right mid-upper quadrant. An abdominal sonogram showed a hypoechoic mass between the liver and the right kidney with no evidence of acute cholecystitis. A CT scan of the abdomen with IV contrast showed a lobulated mass invading the right adrenal gland, measuring 5.4×4.3×5.1 cm, with a post-contrast density measurement of 30 Hounsfield units. Laboratory tests showed plasma renin of 1.8 (upper limit of normal ULN 4.3 ng/ml/h), aldosterone of 8.6 (ULN 21 ng/dl), plasma metanephrine of <0.2 (ULN 0.50 nmol/l), and plasma normetanephrine of 0.49 (ULN 0.90 nmol/l). Additionally, his cortisol level after dexamethasone suppression was 0.9 (ULN 22.4 ug/dl). He underwent a right-sided laparoscopic adrenalectomy. The histopathological testing returned as a high-grade undifferentiated malignant neoplasm consistent with leiomyosarcoma. The IHC stains showed positive staining for SMA, CD10, and GATA3. He underwent whole-body PET/CT that showed multiple hypermetabolic abnormalities, including the right adrenalectomy bed, with a possible tumor invading the right upper renal pole. Systemic chemotherapy with doxorubicin and dacarbazine was initiated. Foundation panel testing showed NF1 loss on exons 2-3, CDKN2A/B CDKN2A rearrangement on exon 2, and TP53 loss on exons 1-4. He has received two rounds of chemotherapy, with no evidence of disease progression. DISCUSSION: Adrenal leiomyosarcoma usually originates from the smooth muscle cells of the adrenal or adjacent vascular structures. The tumor is asymptomatic until it enlarges and compresses the surrounding structures. Currently, there are about 50 reported valid cases (2) with no reports of NF-1 exon loss to our knowledge. The primary treatment is radical surgery with or without adjuvant chemotherapy and radiotherapy. Foundation panel testing showing NF-1 and TP53 exon loss may guide future targeted therapy. REFERENCES: 1-Fatema Jabarkhel, Henri Puttonen, Lina Hansson, Andreas Muth, Oskar Ragnarsson, Primary Adrenal Leiomyosarcoma: Clinical, Radiological, and Histopathological Characteristics, Journal of the Endocrine Society, Volume 4, Issue 6, June 2020. 2-Bahador Oshidari, Amir Zamani, Hooman Bahrami-Motlagh, Elena Jamali, Setareh Mahmoodi, Manoochehr Ebrahimian, Primary leiomyosarcoma of the adrenal; a case report, International Journal of Surgery Case Reports, Volume 90, 2022, 106707. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.