We report a case of 65-year male patient, a known hypertensive and a chronic smoker, who presented to the Civil Hospital, Karachi with complaints of cough, hemoptysis and shortness of breath for three weeks. The chest radiograph showed left apical solitary pulmonary nodule (SPN) and aneurysmal dilatation of the descending thoracic aorta. He was further investigated with contrast enhanced computed tomography (CECT) scan of chest, which apart from demonstrating malignant pulmonary lesion, surprisingly revealed Stanford type B descending thoracic aortic dissecting aneurysm with intramural hematoma, jeopardising renal and splanchnic circulation. An asymptomatic dissecting aortic aneurysm is relatively rare. To the best of authors' knowledge, less than 15 case reports have been published in the international literature.