An 80-year-old woman is brought to the hospital due to 3 weeks of persistent fever, pleuritic chest pain, and productive cough. The patient was seen in the office 2 weeks ago for these symptoms and was given a week-long course of levofloxacin due to suspected right lower lobe pneumonia. She has a history of type 2 diabetes mellitus and dementia and resides in a nursing home. Temperature is 38.3 C (100.9 F), blood pressure is 130/78 mm Hg, pulse is 88/min, and respirations are 18/min. Oxygen saturation is 96% on room air. Examination shows decreased breath sounds at the right lower lobe. Chest imaging reveals increased right lower lobe infiltrate, right pleural effusion, and right-sided hilar adenopathy compressing the middle lobe bronchus. What is the most likely cause of this patient's condition?
Primary pulmonary tuberculosis | |
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AFB = acid-fast bacilli; PPD = purified protein derivative. | |
This patient was seen 2 weeks ago due to acute cough, fever, pleurisy, and suspected right lower lobe community-acquired pneumonia. Despite treatment with levofloxacin (a first-line agent), she has persistent symptoms, suggesting an alternate diagnosis. Given her advanced age, diabetes mellitus, high-risk communal living situation (eg, nursing home), and radiographic findings (including compressive hilar lymphadenopathy), suspicion should be raised for primary pulmonary tuberculosis (TB).
Most patients first exposed to TB have asymptomatic primary infection because the organism is rapidly contained within granulomas and can become "latent" if the body fails to clear the bacteria; they are at risk of secondary (reactivation) TB later in life. In contrast, ~10% of adults first exposed to TB develop symptomatic primary disease ("progressive primary TB"); risk factors for primary progression include impaired immunity due to comorbid conditions (eg, diabetes mellitus, renal disease, HIV), advanced age, or immunosuppressive medications.
Manifestations typically progress over weeks and include fever, pleurisy, and cough. In contrast to reactivation TB (usually marked by cavitary infiltrates), radiography in primary TB often shows a lobar infiltrate (due to unchecked mycobacterial replication) and significant ipsilateral hilar lymphadenopathy. Compression of the right middle lobe (multiple surrounding lymph nodes, relatively longer length) and pleural effusions may also occur.
(Choices A and B) Hilar lymphadenopathy typically reflects infection (eg, TB), neoplasm (eg, lymphoma, lung cancer), or inflammation (eg, sarcoidosis). Lymphoma and sarcoidosis often lead to bilateral, rather than unilateral, lymphadenopathy; and a lobar infiltrate would be uncommon. Sarcoidosis is associated with patchy, reticular pulmonary infiltrates and classically arises in young adults.
(Choice D) Viral pneumonia typically causes acute symptoms over days and can be associated with concurrent upper respiratory manifestations (eg, rhinorrhea, sore throat); 3 weeks of progressive manifestations makes this less likely, and patchy, bilateral, interstitial infiltrates (rather than lobar infiltrates) would be more common.
Educational objective:
Primary pulmonary tuberculosis typically presents with several weeks of fever, cough, and pleurisy. Imaging usually shows a lobar infiltrate, significant hilar lymphadenopathy, and (sometimes) pleural effusion. Suspicion should be raised in those who reside in high-risk settings or have impaired immunity, particularly when treatment for common pulmonary diseases (eg, pneumonia) does not improve symptoms.