A 54-year-old woman comes to the emergency department due to persistent nonproductive cough, mild shortness of breath, and sharp, right-sided chest pain over the last week. The patient has been taking moxifloxacin prescribed by her primary care physician for the last 5 days, but her symptoms have not improved. She was diagnosed with early-stage right breast cancer 5 months ago and underwent lumpectomy and radiation therapy, which she completed 6 weeks ago. Her other medical issues include hypertension, hyperlipidemia, and gastroesophageal reflux disease. The patient has had no prior respiratory problems and is a lifelong nonsmoker. Temperature is 38.4 C (101.1 F), blood pressure is 150/90 mm Hg, pulse is 80/min, and respirations are 15/min. Examination reveals crackles over the right lower lung with dullness on percussion. The remainder of the examination is unremarkable. Laboratory studies reveal a leukocyte count of 13,000/mm³. Chest x-ray is shown below. Previous chest x-ray performed at the time of the patient's breast cancer diagnosis was unremarkable, and echocardiography revealed a normal left ventricular ejection fraction, evidence of diastolic dysfunction, and no significant valvular abnormalities. This patient would most likely respond to which of the following therapies?

Question

Quizplus · Accepted Answer

This patient's recent chest wall radiation and unilateral right-sided infiltrate without improvement on antibiotic therapy is consistent with acute radiation pneumonitis (ARP). Patients usually present with antibiotic-nonresponsive pneumonia 4-12 weeks after neck or thoracic radiation treatment. Fever, dyspnea, cough, and pleuritic chest pain are common, as is leukocytosis. Examination usually shows crackles and/or pleural rub with up to 10% of patients developing pleural effusion. Chest x-ray in ARP may show perivascular haziness, and chest CT can show patchy, ground-glass alveolar infiltrates or consolidative opacities. The affected lung tissue is usually confined to the radiation treatment port and may form a distinct boundary with adjacent normal parenchyma, a so-called straight-line effect. The condition typically progresses within 6-12 months to fibrotic radiation pneumonitis, which has a similar presentation, although fever is less common and imaging typically shows volume loss and coarse reticular/dense opacities. The diagnosis of ARP is made by a compatible clinical presentation combined with exclusion; bronchoscopy may be necessary in some patients to rule out competing diagnoses (eg, infection, malignancy). Treatment for ARP includes prednisone for 2 weeks with a gradual taper over 3-12 weeks; however, this is unlikely to benefit established fibrotic disease. (Choice A) Doxycycline is indicated for atypical bacterial pneumonia; however, moxifloxacin provides atypical coverage. Failure to improve on moxifloxacin makes atypical bacterial pneumonia unlikely. (Choice B) Furosemide would treat volume overload due to heart failure; however, bibasilar crackles would be expected and pleuritic chest pain would be unusual. (Choice D) Trimethoprim-sulfamethoxazole treats Pneumocystis pneumonia, which usually presents with diffuse, bilateral interstitial or alveolar infiltrates in patients who are immunosuppressed. The diagnosis is unlikely in this patient with no known impairment in cell-mediated immunity (eg, HIV). (Choice E) Fungal infections with endemic (eg, histoplasmosis) or opportunistic (eg, aspergillosis) organisms can mimic bacterial pneumonia. However, endemic fungi are not typically treated with voriconazole; pulmonary aspergillosis classically manifests with nodular opacities, sometimes with cavitation (chronic necrotizing aspergillosis), and affected patients are typically neutropenic (invasive aspergillosis). ARP is a more likely diagnosis in this patient who has not received chemotherapy, has a relatively nontoxic presentation, and recently underwent radiation therapy. Educational objective: Patients receiving thoracic or neck irradiation are at risk for acute radiation pneumonitis, which usually presents with antibiotic-nonresponsive pneumonia 4-12 weeks after radiation exposure. Treatment for acute disease includes prednisone for 2 weeks followed by a gradual taper over 3-12 weeks. __________ References: American Society of Clinical Oncology clinical evidence review on the ongoing care of adult cancer survivors: cardiac and pulmonary late effects (http://www.ncbi.nlm.nih.gov/pubmed/17577017) Radiation pneumonitis: a mimic of infectious pneumonitis (http://www.ncbi.nlm.nih.gov/pubmed/7481128)

A 54-Year-Old Woman Comes to the Emergency Department Due to Persistent