TOPIC: Lung Cancer TYPE: Fellow Case Reports INTRODUCTION: Pulmonary sequestration is the second most common pulmonary congenital abnormality and is rarely associated with malignancy. We present a case of a young woman with hemoptysis found to have two rare concurrent lung pathologies: a lung carcinoid tumor within a pulmonary sequestration. CASE PRESENTATION: 21 year old female presents following an episode of sudden onset hemoptysis. Patient's medical history was notable for two prior episodes of pneumonia in her teenage years. A CT chest angiogram was obtained and revealed a right upper lobe highly vascular mass-like consolidation. This was followed by bronchial artery angiography which identified a torturous bronchial arterial blood supply to the abnormal area of parenchyma with a large draining vein. Patient underwent a 90 minute right upper lobe robotic resection and the abnormal area was identified with an aberrant arterial blood supply suggestive of a pulmonary sequestration. Pathology consistent with typical carcinoid tumor. Patient was discharged home on post operative day 1 and follow up imaging has not shown recurrence. DISCUSSION: Pulmonary sequestration describes an area of abnormal lung tissue with an anomalous systemic arterial blood supply. It accounts for approximately 6% of all lung congenital abnormalities predominantly affecting males 4:1. Typically patients remain asymptomatic and this finding is incidentally noted on imaging. If superinfected this can be confused with a consolidative pneumonia. Therefore, typical presentation in adults includes history of recurrent infections and hemoptysis. These features are also shared with a primary lung malignancy. Typical carcinoid tumors are indolent neuroendocrine tumors that progress slowly and rarely metastasize. Although primary lung carcinoid tumors are rare, accounting for 1% of lung cancers, it is the most common lung malignancy in children and adolescents. The mainstay of treatment, like pulmonary sequestration, involves resection. Further staging and pathological findings determine additional therapies. This case demonstrates the considerations required in the diagnostic approach of a poorly characterized lesion when a patient presents with a life threatening condition such as hemoptysis. The initial CT imaging showed a vascular lesion, however the degree of aberrant arterial blood supply was only appreciated following bronchial angiography. Endobronchial biopsy carried an increased risk of hemorrhage and may have been inadequate to diagnose the underlying malignancy and sequestration. Therefore, a surgical approach was favored. CONCLUSIONS: This case of an uncommon primary carcinoid lung malignancy identified within a rare congenital abnormality of a pulmonary sequestration highlights the importance of carefully considering these atypical diagnoses and the multidisciplinary approach required for successful diagnosis and treatment. REFERENCE #1: Corbett HJ, Humphrey GM. Pulmonary sequestration. Paediatr Respir Rev. 2004 Mar;5(1):59-68. doi: 10.1016/j.prrv.2003.09.009. PMID: 15222956. REFERENCE #2: Chakraborty RK, Modi P, Sharma S. Pulmonary Sequestration. [Updated 2021 Mar 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK532314/ REFERENCE #3: Borczuk AC. Pulmonary Neuroendocrine Tumors. Surg Pathol Clin. 2020 Mar;13(1):35-55. doi: 10.1016/j.path.2019.10.002. Epub 2019 Nov 29. PMID: 32005434. DISCLOSURES: No relevant relationships by Robert Cerfolio, source=Admin input No relevant relationships by David Chen, source=Web Response No relevant relationships by Carina Iskandir, source=Web Response No relevant relationships by Benjamin Kwok, source=Web Response No relevant relationships by Elizabeth Morris, source=Web Response No relevant relationships by Roxana Sulica, source=Web Response