A 25-year-old man comes to the emergency department due to several episodes of hemoptysis over the past 2 hours. The patient has no chronic medical conditions and takes no medication. He has never smoked cigarettes. Vital signs are normal. BMI is 27 kg/m². Lung examination is normal. CT scan of the chest with contrast reveals a 3.2-cm, avidly enhancing homogenous mass, as seen in the exhibits, with an endobronchial component at the left hilum. What is the most likely diagnosis in this patient?

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11ec25c8_d941_d5c1_bc81_d378cbd07678_MD0003_00 This young patient's hemoptysis and radiographic findings (eg, mass size >3 cm, significant contrast enhancement) are concerning for malignancy. Although common forms of lung cancer (eg, squamous cell carcinoma, adenocarcinoma) do not typically occur in young nonsmokers, these individuals occasionally develop lung cancer due to bronchial carcinoid (Choice C). Bronchial carcinoid is a neuroendocrine malignancy derived from Kulchitsky (ie, enterochromaffin) cells in the bronchial epithelium. It typically forms in the proximal airway and presents with bronchial obstruction (eg, wheezing, dyspnea, recurrent pneumonia in the distal lung) or tumor bleeding (eg, hemoptysis). CT scan with contrast usually reveals avid contrast enhancement due to the highly vascular nature of the tumor and an endobronchial component due to extension of the lesion into the bronchial lumen. The mass can be homogenous in appearance or have calcified areas. Bronchoscopy with biopsy is usually performed to confirm the diagnosis. contrast enhancement (Choices A and C) Small cell and squamous cell lung cancers can also present as contrast-enhancing primary masses involving the central airways, frequently causing hemoptysis due to endobronchial invasion. However, they almost always occur in active or heavy former smokers. Small cell carcinoma most often presents radiographically as a bulky hilar and mediastinal mass; squamous cell carcinoma often presents with central cavitation (ie, heterogeneous density) due to tumor necrosis. (Choice D) Pulmonary tuberculosis (TB) can cause hemoptysis. Active TB infection can very occasionally present with a solid, contrast-enhancing mass known as a tuberculoma. However, patients generally have established risk factors (eg, cellular immunodeficiency, contact exposure), other constitutional symptoms (eg, malaise, fever, night sweats, weight loss) and cough, and cavitary pulmonary infiltrates in the upper lobes. Educational objective: Bronchial carcinoid tumors are the most common lung malignancy in young nonsmokers. They typically arise in the proximal airway and cause airway obstruction (eg, dyspnea, wheezing, postobstructive pneumonia) or hemoptysis. CT scan with contrast usually reveals an avidly enhancing (ie, hypervascular) mass with an endobronchial component.

A 25-Year-Old Man Comes to the Emergency Department Due to Several