A 37-year-old man with HIV comes to the urgent care clinic due to 2 months of cough. The cough is productive of sputum, particularly in the early morning, and is sometimes associated with streaks of blood. He drinks alcohol and uses intravenous illicit drugs. The patient was hospitalized 4 months ago due to alcohol-withdrawal seizures. CD4 count at that time was 520/mm³. Temperature is 37.7 C (99.9 F), blood pressure is 130/80 mm Hg, pulse is 75/min, and respirations are 14/min. Oxygen saturation is 98% on room air. Lung examination reveals crackles and rhonchi over the right upper lung field. No cardiac murmurs or rashes are present. Chest x-ray findings are shown in the image below: Which of the following is the most likely diagnosis for this patient?

Question

Quizplus · Accepted Answer

11ec25c8_d473_1039_bc81_e3cdf4684567_MD0003_00 This patient with HIV has a chronic cough and a cavitary upper lobe lung lesion, raising strong suspicion for reactivation tuberculosis (TB). Most healthy patients exposed to TB never develop symptoms due to the generation of granulomas that wall off the bacilli and prevent spread (latent TB). However, because maintenance of granulomas is dependent on cytokine signaling between CD4 T lymphocytes and macrophages, patients with impaired immunity are at substantially higher risk of TB reactivation than the general population. HIV is particularly associated with TB reactivation (30- to 100-fold increased risk) due to virus-mediated immune dysregulation, cytokine signaling abnormalities, and CD4 T-lymphocyte destruction. CD4 T lymphocytes and macrophages Manifestations of reactivation TB generally include weeks of progressive fever, weight loss, and cough; the cough is initially minimally productive and greatest in the morning due to pooling of secretions overnight but eventually becomes more productive, persistent, and, sometimes blood-streaked. Because Mycobacterium tuberculosis is an aerobic, slow-growing organism, it preferentially attacks the upper lobes of the lung, where there is high oxygen tensions and slow lymphatic drainage, allowing the organism to accumulate. Chest imaging typically reveals cavitary lesions with surrounding inflammation in the upper pulmonary fields. Diagnosis requires identification of the organism in sputum samples. (Choice A) Aspiration pneumonia can cause a cavitary infiltrate and is common in those with alcohol/substance use disorder. Most cases occur in the lower lobes (particularly the right lower lobe), but it can occasionally cause upper lobe lesions due to recumbent aspiration. Patients typically have several days or a couple weeks of dyspnea, cough productive of foul-smelling sputum, and fever. This patient's 2-month history of cough associated with hemoptysis and an upper lobe cavitation makes TB far more likely, particularly given his HIV status. (Choices B and D) Cryptococcal and Pneumocystis pneumonias are AIDS-defining illnesses that typically occur at CD4 counts <200/mm³. This patient had a CD4 count of 520/mm³; it is highly unlikely that his CD4 count is now low enough to have either opportunistic infection. Furthermore, neither pulmonary infection typically leads to cavitation. Cryptococcus typically causes patchy infiltrates or nodular lesions, and Pneumocystis usually causes diffuse alveolar infiltrates. (Choice E) Septic emboli can occur in patients with intravenous drug use (eg, from thrombophlebitis) and cause hemoptysis from pulmonary infarction. However, most cases are peripheral and multifocal (ie, would be unlikely to cause a single, large cavitary lesion), and patients are acutely, not chronically, ill (eg, fever, dyspnea) due to a large burden of the disease. Educational objective: Patients with HIV have a much higher risk of reactivation tuberculosis than the general population. Patients typically have subacute or chronic symptoms (eg, fever, fatigue, cough, weight loss, night sweats). Upper lobe cavitary lesions are common on chest x-ray. References: Tuberculosis and HIV: a partnership against the most vulnerable. (http://www.ncbi.nlm.nih.gov/pubmed/14556429)

A 37-Year-Old Man with HIV Comes to the Urgent Care