CAVITARY LUNG LESION

 

• What defines a cavity in the context of pulmonary imaging?
• A cavity is a gas-filled space within a nodule, mass, or area of parenchymal consolidation, characterized by a clearly defined wall > 4 mm thick.
• How are acute and chronic cavities differentiated based on duration?
• Acute and subacute cavities are < 12 weeks old in terms of prior imaging or duration of symptoms. Chronic cavities are ≥ 12 weeks old, following the definition of chronic conditions lasting 12 weeks or longer.
• Which conditions can mimic cavities on chest imaging?
• Conditions that mimic cavities include cysts, emphysema, infected bullae, and cystic bronchiectasis.
• What are the distinguishing features on chest imaging that can guide clinicians to specific diagnoses?
• Peripheral nodules in varying stages of cavitation suggest conditions like septic emboli, pulmonary Langerhans cell histiocytosis, or infarction. Bronchiectasis and small airways disease typically indicate chronic infection. Halo and reversed halo signs are associated with rheumatologic diseases, infections, and malignancies. Malignant cavitary lesions may show irregular internal walls.
• How can clinicians determine if they are dealing with true cavities or their mimics?
• True cavities need differentiation from cystic disease, emphysema, infected bullae, and cystic bronchiectasis based on specific radiographic appearances outlined in diagnostic tables.
• What steps should clinicians take based on disease duration in evaluating cavitary lung disease?
• For acute or subacute cavities (< 12 weeks), initial steps include ruling out recent infection through clinical features and laboratory tests. For chronic cavities (≥ 12 weeks), further evaluation is needed for conditions like chronic infections, including tuberculosis, discussed subsequently.
• What clinical features suggest an acute bacterial infection in the context of cavitary lung disease?
• Features include fever, chills, and productive cough. Laboratory indicators may include elevated white blood cell count with left shift and elevated procalcitonin levels.
• What laboratory tests are relevant for diagnosing fungal infections associated with cavitary lung disease?
• Tests such as blood cultures, β-D-glucan levels, galactomannan levels, and measurements of specific fungal antigens in blood and urine are important for fungal infections.
• How does Mycobacterium tuberculosis manifest in the context of cavitary lung disease?
• Although it can present acutely, tuberculosis more commonly manifests chronically with cavitary lesions, necessitating distinct diagnostic and management approaches.

These questions and answers summarize key aspects of cavitary lung disease, including definitions, differential diagnoses, imaging features, and diagnostic strategies, aiming to guide clinicians in its evaluation and management.

Which organisms are most frequently implicated in causing cavitary diseases of the lung?

• Streptococcus species and Klebsiella pneumoniae are the most common causative organisms. Other less frequent isolates include Staphylococcus aureus, Pseudomonas aeruginosa, Haemophilus influenzae (type B), Acinetobacter species, Escherichia coli, and Legionella species.

What are the contributing clinical factors associated with cavitary lung diseases?

• Contributing clinical factors include alcoholism, diabetes mellitus, generalized convulsive disorders, drug abuse, older age, and dental infections.

What are the typical clinical symptoms and laboratory findings associated with cavitary lung diseases?

• Typical symptoms include high fevers, night sweats, cough with foul-smelling sputum, hemoptysis, fatigue, and weight loss. Laboratory abnormalities include leukocytosis with a left shift and elevated levels of C-reactive protein, erythrocyte sedimentation rate, and procalcitonin.

Describe the radiographic characteristics of a lung abscess.

• A lung abscess appears radiographically as a cavity with thick walls, irregular luminal margins, and outer borders. It typically demonstrates an air-fluid level and is usually unilateral and solitary. Lung abscesses predominantly occur in the posterior segments of the upper lobes and superior segments of the lower lobes.

What are the characteristic features of acute necrotizing pneumonia?

• Acute necrotizing pneumonia is often caused by organisms such as Staphylococcus aureus, Streptococcus pneumoniae, Klebsiella pneumoniae, Haemophilus influenzae, and Pseudomonas aeruginosa. Patients present with severe illness, cough, fever, hypoxia, tachycardia, tachypnea, and can rapidly progress to respiratory failure and septic shock. Radiographically, it presents as areas of consolidation containing multiple foci of poorly defined low attenuation areas suggestive of necrosis.

How does lung gangrene manifest on chest CT scans?

• Lung gangrene is characterized by areas of central necrosis affecting more than 50% of the involved lobe. CT findings include obscuration of the pulmonary arterial supply to the affected segment or lobe, paucity of contrast material uptake in the lung parenchyma, and a propensity to occur in regions of the lung that are less gravity-dependent compared to abscesses.

What are the radiographic features of septic pulmonary emboli?

• Septic pulmonary emboli appear as well-defined, peripheral or subpleural nodules of various sizes (0.5-3.5 cm) with evidence of cavitation in up to 85% of patients. They are often associated with nodules appearing in various stages of cavitation due to repeated seeding of the lungs, typically from endocarditis.

What are the clinical and radiographic features of pulmonary nocardiosis?

• Pulmonary nocardiosis, commonly caused by Nocardia asteroides, presents with pulmonary nodules, consolidation, and cavitation on imaging. Radiographically, nodules range from 0.6 to 2.9 cm and may show a crazy-paving appearance. Pleural effusion and associated bronchiectasis can also be present.

What is the most common Cryptococcus species encountered in temperate climates, and how does it typically manifest in the lungs?

• Cryptococcus neoformans is the most common species encountered in temperate climates. It causes pulmonary involvement after inhalation of spores, primarily affecting immunocompromised individuals. Radiographically, it manifests as multiple bilateral peripheral nodules and masses, with cavitation occurring within nodules or masses, especially in immunocompromised hosts.

What are the risk factors and clinical manifestations of Coccidioidomycosis?

• Coccidioidomycosis is caused by Coccidioides fungi endemic to the southwestern United States, parts of Mexico, and Central and South America. Risk factors include AIDS, hematologic malignancies, pregnancy, diabetes, cardiopulmonary disease, smoking, and male sex. Clinical manifestations range from asymptomatic or mild influenza-like symptoms to acute bacterial pneumonia-like symptoms such as cough, fever, and chest pain. Radiographically, it presents with focal or multifocal consolidation and pulmonary nodules, with cavities seen in 2% to 8% of cases.

Describe the pulmonary manifestations and diagnostic tests for Aspergillosis.

• Aspergillus can cause various pulmonary diseases including aspergilloma, chronic necrotizing aspergillosis (CNA), and invasive pulmonary aspergillosis (IPA). IPA is common in immunocompromised patients and manifests with multiple pulmonary nodules (> 1 cm) associated with a halo sign on imaging, indicating pulmonary hemorrhage. Cavitation may follow, presenting as an air crescent sign. Diagnostic tests include galactomannan and b-D-glucan assays.

What are the clinical features and radiographic findings suggestive of Mucormycosis?

• Mucormycosis, caused by molds like Rhizopus and Mucor, typically affects severely ill patients with poorly controlled diabetes or immunocompromise. Clinical features include fever, cough, dyspnea, pleuritic chest pain, and hemoptysis. Radiographically, it overlaps with IPA, showing masses, nodules, halo signs, consolidation, and cavitation. A reversed halo sign may also be observed.

How does chronic cavities ($ 12 weeks in duration) differ in terms of differential diagnosis compared to acute or subacute cavities?

• Chronic cavities raise suspicion for chronic infections, malignancy, or autoimmune disorders. Chronic infections typically present with prolonged symptoms such as fevers, weight loss, chronic cough, hemoptysis, and fatigue. Malignancy is more likely in older patients with a smoking history or personal/family history of cancer. Autoimmune disorders are suggested by connective tissue disease history, arthralgias, myalgias, and positive serologic tests.

What is the typical clinical presentation and radiographic manifestation of tuberculosis (TB)?

• Patients with pulmonary TB commonly present with chronic cough, sputum production, weight loss, fevers, night sweats, loss of appetite, and hemoptysis. Radiographically, fibrocavitary disease is seen in approximately 50% of patients with reactivation TB, primarily in the apical and posterior segments of the upper lobes or superior segments of the lower lobes. This disease is characterized by nodular densities, linear fibrous scars, volume loss, and cavitation, which may become thin-walled and smooth with treatment.

What are the characteristics of nontuberculous mycobacteria (NTM) infection, particularly Mycobacterium avium complex (MAC)?

• NTM infections, especially by MAC, are associated with profound immunosuppression (e.g., HIV, transplant) or structural lung disease (e.g., COPD, cystic fibrosis). Symptoms include chronic productive cough, hemoptysis, malaise, fatigue, and weight loss. Radiographically, NTM infections resemble reactivation TB with upper lobe fibrocavitary disease, but cavities due to MAC tend to be smaller or thin-walled and progress more slowly. Tree-in-bud opacities and bronchiectasis are common findings.

Describe chronic necrotizing aspergillosis (CNA), including its clinical and radiographic features.

• CNA is an indolent, destructive process caused by Aspergillus species in patients with underlying structural lung disease such as COPD or prior TB. Symptoms include fever, cough, sputum production, dyspnea, hemoptysis, anorexia, weight loss, and malaise. Diagnostic tests include Aspergillus IgG antibody and polymerase chain reaction. Radiographically, it presents as unilateral or bilateral cavitary lesions in the upper lobes with adjacent pleural thickening, which may progress to a bronchopleural fistula.

What is histoplasmosis, and how does it manifest radiographically?

• Histoplasmosis, caused by Histoplasma capsulatum endemic in certain regions of the United States, presents with symptoms of productive cough, malaise, fevers, night sweats, and weight loss. Radiographically, cavities are typically found in the upper lobes, often associated with fibrosis in up to 30% of cases. Punctate calcifications in spleen, liver, and mesenteric lymph nodes are suggestive of previous infection.

Discuss pulmonary blastomycosis, including its clinical and radiographic characteristics.

• Pulmonary blastomycosis, caused by Blastomyces dermatitidis endemic in specific regions of the United States and Canada, typically affects immunocompetent individuals. Symptoms include cough, fevers, night sweats, weight loss, and malaise. Radiographically, cavities are less common compared to histoplasmosis and TB, but when present, they can have thin or thick walls, be single or multiple, and are more frequently located in the upper lobes.

Based on the information provided, here are the questions and answers for Step 6: Malignancy and Step 7: Autoimmunity:

Step 6: Malignancy

• What is the incidence of cavities in primary lung cancer?
• Cavities are relatively common in primary lung cancer, with an incidence of up to 11% on plain chest radiographs and up to 22% on CT scans. The maximum wall thickness of the cavity has been studied, with a thickness >15 mm indicating malignancy in more than 90% of cases on plain radiographs. However, on CT scans, malignant cavities are more likely to have an irregular internal wall and indentation of the outer wall.
• What are the typical radiographic characteristics of primary cavitary lung cancer?
• Primary cavitary lung cancer, especially non-small cell lung cancer like squamous cell carcinoma (69%-81%), typically manifests with cavities that show an upper lobe predominance. Radiographically, these cavities may appear with thick and irregular walls or very smooth and thin, simulating a cyst. Other malignancies, such as pulmonary metastases from squamous primaries (head and neck, cervical, skin, or sarcomas), can also cavitate.

Step 7: Autoimmunity

• Describe the pulmonary manifestations of rheumatoid arthritis (RA).
• RA is associated with various pulmonary complications, including interstitial lung disease (ILD), pleural disease, and rheumatoid nodules. Rheumatoid nodules, found in 20% of patients, appear as multiple well-defined nodules with occasional central necrosis on radiographs. High-resolution CT scans typically show a usual interstitial pneumonia pattern with subpleural, basilar-predominant reticular abnormalities, honeycombing, and traction bronchiectasis.
• What is granulomatosis with polyangiitis (GPA), and how does it manifest radiographically?
• GPA is characterized by necrotizing granulomatous inflammation and vasculitis of the upper and lower respiratory tract and kidneys. Radiographically, GPA commonly presents with multiple and bilateral lung nodules in 40% to 70% of patients, with cavitation occurring in 25% to 50% of these nodules, particularly in those >2 cm in size. Additional findings include chronic airway inflammation, bronchial wall thickening, bronchiectasis, and foci of parenchymal consolidation.

https://emcrit.org/ibcc/cavitation/

1. What is a cavitary lesion?

Q: What is a cavitary lesion?

A: A cavitary lesion is defined as a gas-filled space within a nodule, mass, or area of parenchymal consolidation in the lung. Cavitation often implies a necrotic process with lung tissue destruction and may be associated with treatable diseases like tuberculosis or malignancy.

2. What are common causes of cavitary lesions?

Q: What are common causes of cavitary lesions?

A: Cavitary lesions can be caused by:

• Infections:
  • Bacteria: Necrotizing pneumonia, septic pulmonary emboli, lung abscess.
  • Fungi: Invasive pulmonary aspergillosis, chronic cavitary pulmonary aspergillosis, mucormycosis, Cryptococcus, dimorphic fungi (e.g., Coccidiomycosis, Histoplasmosis, Blastomycosis).
  • Mycobacteria: M. tuberculosis (post-primary), non-tuberculous mycobacteria, Nocardia, Actinomycosis.
  • Rare: Rhodococcus equi, Tularemia, Tracheobronchial papillomatosis, Echinococcus.
• Malignancy: Lung cancer (especially squamous cell carcinoma), metastatic cancers (e.g., squamous cell carcinoma from head/neck, esophagus, or cervix, metastatic adenocarcinoma, melanoma), pulmonary lymphoma.
• Inflammatory Conditions: Granulomatosis with polyangiitis (GPA), rheumatoid arthritis necrobiotic nodules, rare sarcoidosis, pulmonary pyoderma gangrenosum.
• Other: Pulmonary infarction due to pulmonary embolism.

3. What radiological clues can help differentiate cavitary lesions?

Q: What radiological clues can help differentiate cavitary lesions?

A: Important radiological clues include:

• Location: Apex (suggests mycobacteria, fungus, squamous cell carcinoma), anterior upper lobe (suggests malignancy), posterior segments of upper lobes or superior segments of lower lobes (lung abscess), multifocal peripheral cavitation (septic emboli).
• Number of Lesions: Solitary lesions might suggest primary lung cancer, infection (e.g., lung abscess, tuberculosis), or fungal infection. Multiple lesions might indicate metastatic cancer, lymphoma, or infections (e.g., tuberculosis, invasive aspergillosis).
• Wall Thickness & Irregularity: Thick-walled (>15 mm) and irregular cavities suggest malignancy. Smooth or shaggy walls are more typical for lung abscesses.
• Tree-in-Bud Opacities: Suggest infectious processes, especially mycobacterial infections, or chronic cavitary pulmonary aspergillosis.
• Halo Sign: Ground-glass opacities around a cavitary lesion, often seen with infections (e.g., invasive mold infections, mycobacteria) or certain malignancies.
• Air-Crescent Sign: Crescent of air around a nodule or mass, often seen with invasive pulmonary aspergillosis, aspergilloma, or necrotizing bacterial pneumonia.
• Cheerios Sign: Central lucency in pulmonary nodules resembling Cheerios, indicative of small cavitary lesions or neoplastic growth around a patent airway.

4. What is the significance of the "halo sign" in radiology?

Q: What is the significance of the "halo sign" in radiology?

A: The halo sign is characterized by ground-glass opacities surrounding a cavitary lesion. It is associated with:

• Infections: Septic pulmonary emboli, invasive fungal infections (e.g., aspergillosis, mucormycosis), and certain mycobacterial infections.
• Malignancies: Melanoma, sarcomas, choriocarcinoma, and GPA (granulomatosis with polyangiitis).

5. What does the "air-crescent sign" indicate and what are its causes?

Q: What does the "air-crescent sign" indicate and what are its causes?

A: The air-crescent sign is a crescent of air surrounding a pulmonary nodule or mass and indicates:

• Infection: Invasive pulmonary aspergillosis (particularly during recovery), aspergilloma, necrotizing bacterial pneumonia, Echinococcal cysts.
• Neoplasms: Cavitating neoplasms (primary or metastatic).
• Other Causes: Intracavitary blood clot, Rasmussen aneurysm, granulomatosis with polyangiitis.

6. What is the "Cheerios sign" and what conditions can it indicate?

Q: What is the "Cheerios sign" and what conditions can it indicate?

A: The Cheerios sign is defined as pulmonary nodules with central lucency resembling Cheerios. It may indicate:

• Malignancy: Lepidic-predominant adenocarcinoma, primary lung cancer, metastatic carcinoma.
• Infections: Fungal infections, GPA (granulomatosis with polyangiitis).
• Other Conditions: Rheumatoid nodules, PLCH (pulmonary Langerhans cell histiocytosis).

https://www.the-hospitalist.org/hospitalist/article/35676/pulmonology/best-approach-to-a-cavitary-lung-lesion-update/#:~:text=A%20cavitary%20lung%20lesion%20is,of%20greater%20than%204%20mm.&text=The%20differential%20for%20these%20lesions,infectious%20and%20non%2Dinfectious%20causes.

Best Approach to a Cavitary Lung Lesion–Update

By Charles A. Pizanis, MD; Riana Wurzburger, MD, MPH; Patrick A. Rendon, MD; James T. Dean III, DO

October 2, 2023

This is an update of our 2015 article on cavitary lung lesion.1

Case

A 60-year-old man with alcohol use disorder presented to the hospital with fatigue, chest pain, and productive cough for two weeks. Additionally, he endorsed a 20-lb weight loss over the previous month which he attributed to a poor appetite. He lived in the southwestern U.S. and had no recent travel. His initial chest X-ray demonstrated a 3.4-cm left upper lobe cavitary lesion (Figure 1).

Overview

Hospitalists frequently encounter patients with cavitary lung lesions on chest imaging and are often faced with initiating their early workup and management. Having a strategy for the initial diagnostics and therapeutics as well as a plan for pre-consultation can assist in streamlining workup.2 Additionally, hospitalists are frequently involved in establishing the initial surveillance strategy for cavitary lung lesions upon discharge, and developing a mental framework for follow-up can assist in optimizing the outpatient transition of care.

A cavitary lung lesion is defined radiographically as a lucent area contained within a consolidation, mass, or nodule. It is further characterized by thick walls of greater than 4 mm.3,4 The differential for these lesions is broad and includes both infectious and non-infectious causes.

Infectious causes

Figure 1: Chest X-ray of a hospitalized patient demonstrating a left upper lobe cavitary lung lesion.

Figure 1: Chest X-ray of a hospitalized patient demonstrating a left upper lobe cavitary lung lesion.

The organisms known to cause cavitary lung lesions are many and include bacteria, fungi, parasites, and viruses (Table 1). Principal among them for consideration, particularly from an infection-control standpoint, is Mycobacterium tuberculosis. Lung abscesses and necrotizing pneumonias, subsets of cavitary lung lesions, carry another unique spectrum of causative organisms. Anaerobic and microaerophilic streptococci (e.g., Streptococcus milleri) make up the majority of identified organisms, and polymicrobial infection is commonly encountered.5,6 Other non-tuberculous mycobacterium such as M. abscessus and M. avium also cause cavitations. Notable aerobic organisms occasionally encountered include Staphylococcus aureus and Klebsiella pneumoniae.6

Fungi and parasites, while rarer than bacterial causes, require significantly different treatment regimens. Aspergillus fumigatus in its invasive form is known to occupy preexisting lung cavities and is identifiable by the presence of a fungal ball (aspergilloma) within the lung cavity.7 Other endemic fungi (e.g., Histoplasmosis capsulatum) have been linked to cavitary lung lesion development.8

Lung cavitation in the setting of COVID-19 infection

Since the COVID-19 pandemic began, several cases of lung cavities in the setting of COVID-19 infection have been reported. In a single-center study reporting on the radiographic appearance and clinical outcomes of 689 hospitalized patients with COVID-19 pneumonia, 3.3% of patients developed lung cavitation. Cavity sizes ranged from 30 to 100 mm in diameter and were solitary or multiple. Bacterial and fungal coinfections were noted in some but not all patients. Notably, cavitations appeared on subsequent and not initial chest imaging in all patients, suggesting lesions represented a delayed complication of COVID-19 infection.9 Mechanisms of cavitation are not fully known but autopsy data have suggested a mixture of thrombotic vascular occlusion accompanied by liquefying necrosis contributing to cavity development.10 Lung cavitation in the setting of COVID-19 pneumonia appears to be a poor prognostic indicator, with death occurring in 50% of patients in the aforementioned case series.9

Non-infectious causes

Several non-infectious causes of lung cavitations exist and should be considered in the differential. These include malignant, rheumatologic, vascular, and infiltrative conditions. A principal consideration of a lung cavity is malignancy. Both primary lung cancers and metastatic cancers are known to cause cavitations, with cancers of squamous cell origin being the cell type most known to cavitate.11 Several rheumatologic conditions have also been linked to lung cavitation. Granulomatosis with polyangiitis, rheumatoid arthritis, and sarcoidosis are all known to cause cavitation. Other less common causes of lung cavitation include pulmonary embolism (usually resulting from pulmonary infarction), Langerhans cell histiocytosis, and amyloidosis.4

Patient characteristics

A focused pulmonary history is essential in guiding the workup. Conditions such as substance use disorders, seizure disorders, or swallowing deficits put patients at risk for aspiration, which is the most common cause of pulmonary abscesses. Immunosuppression, particularly neutropenia or hematologic malignancies, greatly raises the likelihood of infections from fungi and atypical bacteria. Carcinogens such as tobacco smoke or occupational exposure increase the primary lung cancer risk. Finally, circumstances such as travel to endemic regions, homelessness, incarceration, or sick contacts increase the risk of atypical infections such as Mycobacteria or coccidioidomycosis.

Imaging characteristics

While establishing a diagnosis from radiographic findings alone is unlikely, certain imaging cues can narrow the differential. Apical lung lesions are more commonly seen with tuberculosis and primary lung cancer, while the lower lobes are more often involved in necrotic pneumonias, septic emboli, or metastatic disease. Multiple cavitary lesions are more common in autoimmune disease, atypical infections, or metastatic cancer, whereas solitary lesions are more common with primary lung cancer or lung abscesses. Cavity-wall thickness has also been proposed as an effective tool, with thicknesses greater than two cm highly associated with malignancy and benign lesions frequently having thin walls of less than seven mm. Lastly, findings such as associated consolidation or tree-in-bud nodules are more likely to be infectious, while a visible mass within a cavity is almost pathognomonic for an aspergilloma.

Initial diagnostics

Prior to infectious disease or pulmonary consultation, the hospitalist clinician should obtain several tests as part of the initial workup. Additional, more advanced testing may be ordered depending on the likelihood of certain diagnoses on the differential (see Table 2 for suggested pre-consultation evaluation).

Bronchoscopy or biopsy?

While often the etiology of a cavitary lesion can be determined through a focused history and non-invasive workup, certain entities require a more invasive workup with bronchoscopy or percutaneous biopsy. If malignancy is of primary concern, consultation with a pulmonologist should occur to help determine the feasibility of a bronchoscopic biopsy or if interventional radiology is required. Certain patients such as those with hematologic malignancies or immunosuppression are at higher risk for atypical infections and may benefit from earlier bronchoscopy to guide antimicrobial therapy.

What to do at hospital discharge

The frequency of surveillance imaging for cavitary lung lesions will vary based on the etiology. In the case of malignancy, it is determined by cell type, initial staging, and treatment plan. A common question for hospitalists, however, is what the appropriate follow-up and monitoring should be, specifically for lung abscesses. Patients should typically receive an empiric trial of antibiotics before more invasive measures are attempted, as approximately 90% will improve with antibiotic therapy alone.12,13 Resolution on imaging may take several weeks or months and serial chest imaging should be obtained to monitor progress through the course of treatment.1,6 A strategy for imaging can include a repeat  CT four to six weeks into treatment with subsequent imaging depending on clinical and radiographic status.

Should a lung abscess fail to improve with conservative therapy in the expected timeframe (or if the patient demonstrates clinical deterioration), pulmonology consultation is warranted for further diagnostic workup, typically with bronchoscopy to obtain further culture data and look for obstruction.13 Failure to improve despite an adequate trial with appropriate antibiotics may necessitate percutaneous drainage, endobronchial drainage, or, rarely, surgical resection. Depending on abscess location and local expertise, pulmonology, interventional radiology, and/or thoracic surgery consultations may be necessary to guide the next steps in management.1

Back to the case

After initial diagnostics, the patient was started on empiric antibiotics and discharged home with outpatient imaging follow-up. Subsequent chest imaging demonstrated resolution of cavitation and the cause was attributed to aspiration.

Bottom line

Hospitalists are central to driving the care for hospitalized patients with cavitary lung lesions found on imaging. 

Quizz

A 66-year-old man with a history of smoking and cirrhosis who is experiencing homelessness presents to the emergency department with a productive cough and fever for one month. He has traveled around Arizona and New Mexico but has never left the country. His complete blood count is notable for a white blood cell count of 13,000. His chest X-ray reveals a 1.7-cm right upper lobe cavitary lung lesion. Which of the following is the best next step in management?

A. Chest CT with contrast

B. Image-guided biopsy of the lesion

C. Initiation of piperacillin-tazobactam

D. Obtain antinuclear antibody (ANA) testing

E. Sputum smear for acid-fast bacilli

Correct option: Choice A. Chest CT with contrast is the best next step in management; it will allow for the characterization of the cavitary lesion, including whether other masses or lung pathology are present within the lungs.

Choice B. An image-guided biopsy is typically obtained in cases of suspected neoplasm. Although this may be a reasonable diagnostic test later in the workup, it’s not the best next step. If infectious, a biopsy could cause seeding of infection in other areas of the lung and would not significantly change management.

Choice C. Initiation of piperacillin-tazobactam may be prudent if the cavitary lung lesion is suspicious for bacterial infection, which is highly likely in this case. But a more appropriate antibiotic choice would be ampicillin-sulbactam given the low likelihood of a pseudomonal infection inducing the cavitary lung lesion.

Choice D. Ordering an ANA test may be reasonable in this instance although there is nothing specifically worrisome in the stem for an autoimmune etiology. If the patient had a malar rash (or other signs of lupus), this would increase the likelihood of an autoimmune cause. This patient likely has an infection.

Choice E. Sputum smear for acid-fast bacilli is a reasonable choice as it is important to rule out tuberculosis, especially given the history of experiencing homelessness. A chest CT, however, would be a more appropriate next step before an acid-fast bacilli smear is obtained.