A 70-year-old man who lives in a group home is brought to the emergency department due to 3 months of persistent cough and anorexia. The cough occurs mainly in the early morning and is often productive. He has a history of chronic kidney disease, type 2 diabetes mellitus, and an ischemic stroke that resulted in right-sided residual paralysis. He has never smoked cigarettes. Temperature is 38.2 C (100.8 F) , blood pressure is 124/80 mm Hg, pulse is 90/min, and respirations are 16/min. BMI is 22 kg/m². Examination shows cervical lymphadenopathy and muscle wasting. Cardiopulmonary examination shows no abnormalities. Laboratory results are as follows: Chest x-ray is shown in the exhibit.

Tuberculin skin testing is negative. What is the most likely diagnosis?

Question

A 70-year-old man who lives in a group home is brought to the emergency department due to 3 months of persistent cough and anorexia. The cough occurs mainly in the early morning and is often productive. He has a history of chronic kidney disease, type 2 diabetes mellitus, and an ischemic stroke that resulted in right-sided residual paralysis. He has never smoked cigarettes. Temperature is 38.2 C (100.8 F) , blood pressure is 124/80 mm Hg, pulse is 90/min, and respirations are 16/min. BMI is 22 kg/m². Examination shows cervical lymphadenopathy and muscle wasting. Cardiopulmonary examination shows no abnormalities. Laboratory results are as follows:

Chest x-ray is shown in the exhibit.

Tuberculin skin testing is negative. What is the most likely diagnosis?

Quizplus · Accepted Answer

Explanation: Despite his negative tuberculin skin test (TST) result, several features of this elderly patient's presentation are concerning for pulmonary tuberculosis (TB). Risk of reactivation TB is significantly increased (6- to 50-fold) in chronic kidney disease (CKD) due to impairments in cell-mediated immunity (CMI), which usually serves as a protective mechanism against intracellular organisms (eg, latent Mycobacterium tuberculosis). CMI is also required to generate induration against the TST. Therefore, in patients with CKD, TST anergy (false-negative result) is common and a negative TST cannot rule out active TB infection. Younger patients with active pulmonary TB frequently have fever and cough. In contrast, older patients such as this one often have nonspecific symptoms such as weeks or months of fatigue, anorexia, muscle wasting, and weight loss. Mild, productive cough may occur, particularly in the mornings (overnight pooling of secretions). Lymphadenopathy, particularly hilar (seen on this patient's x-ray) and cervical (reflecting lymphatic spread), is common. Laboratory findings suggestive of TB in this patient include: anemia: likely anemia of chronic disease in the setting of inflammation monocytosis (late finding): monocytes differentiate into macrophages, which are important for the granulomatous antimycobacterial response hypergammaglobulinemia (eg, elevated total protein in this patient): reflecting the heterogeneous antibody response against M tuberculosis hypoalbuminemia (late finding, particularly in the elderly): possibly due to inflammatory cytokines stimulating production of acute phase reactants at the expense of albumin; in addition, although not obviously present in this patient, malnutrition often coexists with TB, compounding hypoalbuminemia. Upper lobe cavitation and hilar lymphadenopathy (as seen in this patient) are classic, although older individuals frequently have multifocal radiographic infiltrates. Due to all these differences, the diagnosis of TB in older patients can easily be missed or delayed. cavitation (Choice A) Infectious mononucleosis can cause adenopathy, fever, and systemic symptoms (eg, anorexia, fatigue), some of which can last for a prolonged time. However, it usually affects young adults and would be uncommon in this patient's age group; symptoms typically last a few weeks rather than months; and productive cough and cavitary lesions are not seen. (Choice B) Granulomatosis with polyangiitis presents with upper/lower respiratory symptoms and renal insufficiency (glomerulonephritis). Radiographic findings may include multiple nodules that may be cavitary; a single large cavitary lesion with associated hilar lymphadenopathy is uncommon. In addition, most patients have upper airway symptoms (eg, otitis media, rhinosinusitis). (Choice C) Although small cell lung cancer can cause cough and anorexia, it typically occurs exclusively in smokers and presents with a large hilar mass. Cavitary lesions are more common with squamous cell carcinoma. Educational objective: Pulmonary tuberculosis is common in older individuals with comorbidities (eg, renal failure) due to waning cell-mediated immunity. Older patients often have fatigue, weight loss, and anorexia; cavitation is seen less often on chest x-ray.

A 70-Year-Old Man Who Lives in a Group Home Is