A 20-year-old woman comes to the office for follow-up after being discharged from the hospital 2 weeks ago. The patient has been hospitalized twice in the past 3 months for right lower lobe pneumonia; treatment with antibiotics resolved her symptoms on both occasions, and she currently feels well. Family history is not significant. She has never smoked cigarettes. Temperature is 37.5 C (99.5 F), blood pressure is 120/76 mm Hg, pulse is 88/min, and respirations are 15/min. Oxygen saturation is 96% on ambient air. BMI is 24 kg/m². Oropharynx is clear, and nasal passages are normal. There is no lymphadenopathy. Localized wheezes are present in right lower lobe. There is no clubbing. Complete blood count with differential is normal. Chest radiograph reveals a persistent right lower lobe infiltrate. Which of the following is the most likely diagnosis in this patient?

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11ec25c8_d103_64d5_bc81_2703c495f5ff_MD0003_00 This patient has had 2 episodes of right lower lobe pneumonia over a short time frame. Both infections symptomatically improved with antibiotic therapy, but she continues to have wheezing and a pulmonary infiltrate in that region. Recurrent pneumonia in the same anatomic portion of the lung is usually caused by a structural lesion inside (eg, foreign body, bronchial stenosis) or around (eg, mediastinal lymphadenopathy, neoplasm) the proximal bronchus. Obstruction of the bronchus impairs clearance of fluid from the alveoli, leading to microbial aggregation and a high risk of infection. Although bronchial carcinoid tumors account for 1%-2% of total lung malignancies, they are the leading cause of lung cancer in adolescents and young adults (particularly in those who do not smoke). Tumors are typically slow-growing and round and generally form in the proximal airway; they can present with wheezing, dyspnea, cough due to bronchial obstruction or hemoptysis due to tumor bleeding from hypervascularity. Compared to gastrointestinal carcinoid tumors, bronchial carcinoid tumors produce far less serotonin/vasoactive amines and do not often cause carcinoid syndrome. Recurrent pneumonia can also be seen with systemic disorders (eg, immunodeficiency, cystic fibrosis); however, patients with systemic causes of recurrent pneumonia often have pneumonia in different anatomic regions and infections in other portions of the respiratory tract (eg, sinusitis). (Choice B) Polyarteritis nodosa typically causes gastrointestinal (eg, mesenteric ischemia), renal (eg, infarction), dermatologic (eg, livedo reticularis), and neurologic (eg, mononeuritis multiplex) manifestations. Lung involvement is extremely rare. (Choice C) Pulmonary tuberculosis can cause fever and pulmonary infiltrate; however, it requires multidrug antibiotic therapy over several months for appropriate treatment (unlike in this patient). (Choice D) Squamous cell lung cancer can cause bronchial obstruction with recurrent pneumonia. However, most cases occur in patients who smoke and arise in those with advanced age. This young patient who does not smoke cigarettes is unlikely to have squamous cell cancer. Educational objective: Bronchial carcinoid is the most common lung cancer in adolescents and young adults. It typically presents with proximal airway obstruction, leading to dyspnea, wheezing, and recurrent pneumonia in the same lobe of the lung. Carcinoid syndrome is much less common than with gastrointestinal carcinoid tumors.

A 20-Year-Old Woman Comes to the Office for Follow-Up After