SESSION TITLE: Medical Student/Resident Diffuse Lung Disease SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Lymphangioleiomyomatosis (LAM) is a rare multisystem disease that affects almost exclusively women in the reproductive age that can occur sporadically or in association with tuberous sclerosis (TB). LAM is characterized by invasion of the lungs and axial lymphatics by smooth muscle like cells termed LAM cells which have mutations in TSC1 or more commonly TSC2 resulting in activation of mTOR, abnormal cellular growth and migration. LAM commonly presents with dyspnea, recurrent pneumothorax and in some cases respiratory failure. Diagnosis is made by a combination of clinical features and the finding of thin walled cysts on CT scanning. In case of doubt, lung biopsy can be made for diagnosis with smooth muscle actin and HMB45 positive cells. Forty percent of patients have renal angiomyolipoma. Treatment is predominantly supportive with oxygen, bronchodilators and sometimes lung transplantation. CASE PRESENTATION: 41 y/o male patient with PMHx of epilepsy presents with abdominal pain that started 4 days ago. Pain was localized on left lower quadrant and left flank, non-radiating, pulsatile with 10/10 intensity and was associated with diarrhea and fever. Physical examination was remarkable for nasal angiofibromas, palpable mass on left lower quadrant and ash leaf spots on lower limbs. Abdominal-Pelvic CT Angiogram was remarkable for multiple bilateral renal angiomyolipomas, largest in the left kidney measuring 20 cm in size with an area of 15 cm of acute hemorrhage. Patient underwent endovascular embolization of renal arteries with no further complications. Due to findings on Abdominal-Pelvic CT Scan consistent with Tuberous Sclerosis, Chest CT Scan was ordered and remarkable for cystic changes in lungs and sclerotic bone lesions. These findings were pathognomonic of LAM and tissue biopsy was not necessary for diagnosis. DISCUSSION: Our patient represents a rare presentation of LAM in male patients; LAM is historically considered uncommon and fatal disease of women of childbearing age. The prevalence of LAM is thought to be 1 to 2.6 patients in 1,000,000 in the general female population. Our case presents a male with a rare disease diagnosed incidentally due to abdominal pain. Patient never presented with respiratory symptoms. Renal angiomyiolipoma could be an incidental finding on most patients. Our case demonstrates an atypical gender presentation with extra pulmonary symptoms that are unusual in LAM. CONCLUSIONS: The fact that this rare and uncommon disease presents in women is not exclusive to this gender. When exploring LAM as a differential diagnosis, males should be included. Reference #1: Johnson, S. R. (2006). Lymphangioleiomyomatosis. European Respiratory Journal. doi:10.1183/09031936.06.00113303 Reference #2: Rhee, J. A., Adial, A., Gumpeni, R., & Iftikhar, A. (2019). Lymphangioleiomyomatosis: A Case Report and Review of Literature. Cureus, 11(1), e3938. https://doi.org/10.7759/cureus.3938 Reference #3: Kristof AS, Moss J. Lymphangioleiomyomatosis. In: NORD Guide to Rare Disorders. Lippincott Williams & Wilkins. Philadelphia, PA. 2003:395-6. DISCLOSURES: No relevant relationships by Sandra Galarza-Vargas, source=Web Response No relevant relationships by Claudia Quiles, source=Web Response No relevant relationships by Jose Torres, source=Web Response