Facilitator Version
Cavitary Lung Lesion Module #24
Created by Patrick Rendon and Marc Montanaro March 2014
Objectives:
- Be able to state the differential diagnosis for a cavitary lung lesion and which risk factors increase the likelihood of certain diagnoses.
- Be able to state the rationale and delineate the evaluation of a cavitary lung lesion.
- Be able to list the bacteria involved and their connection to treatment of a lung abscess.
References:
1. Chung G, Goetz MB. Anaerobic Infections of the Lung. Curr Infect Dis Rep 2000; 2:238.
2. Gadkowski LB and Stout JE. Cavitary Pulmonary Disease. Clin Microbiol Rev. April 2008; 21(2): 305–333.
3.Ryu, Jay, Swensen, Stephen J, Cystic and Cavitary Lung Diseases: Focal and Diffuse. Mayo Clinic Proceedings. June 2003, Vol 78.
4. Zhuang YP, Wang HY, Zhang J, Feng Y, Zhang L. Diagnostic accuracy and safety of CT-guided fine needle aspiration biopsy in cavitary pulmonary lesions. Eur J Radiol.January 2013;82(1):182-6. doi: 10.1016/j.ejrad.2012.09.011. Epub 2012 Oct 15.
CASE
A 63 yo homeless man with alcoholic cirrhosis and history of hepatic encephalopathy presents to the ER with altered mental status. The patient is unable to provide much history due to his alteration in mental status. He is able to endorse some cough and the ER obtains a CXR which reveals a 1.7 cm RUL cavitary lung lesion.
What else do you need to know from the history?
Existence of pulmonary symptoms such ascough (more details on the cough in this situation), hemoptysis, SOB, fevers/chills/night sweats. Also, TB exposure history, travel history (may indicate exposure to endemic fungi), IV drug use (septic emboli) and other HIV risk factors. A smoking history or history of weight loss may indicate malignancy. Joint symptoms/rash or urinary changes may be indicative of vasculitis on the differential diagnosis. History of blackout episodes after drinking alcohol could be significant for aspiration pneumonia as the vast majority of lung abscesses arise from aspiration in patients with underlying periodontal disease.
What areas of the physical exam are most important?
Detailed oral exam to look for periodontal disease with caries and/or abscess. Also, poor dentition is a risk factor for a preponderance of anaerobes. The patient will need a detailed lung exam as well (yes, even though you already have a chest x ray) to get a baseline in case of future changes to his clinical status. Also, the lung exam may reveal subtle findings such as crackles that may not be readily apparent on the CXR as a developing pneumonia or atelectasis for example.
Vital signs are significant for a temperature of 38.0. The physical exam reveals poor dentition with no sign of oral abscess. Lungs are overall clear, and the remainder of the exam is benign. Laboratory studies indicate a leukocyte count of 20,000/µL (20 × 109/L), a blood urea nitrogen level of 28 mg/dL, and a normal serum creatinine.
What is your initial differential for this cavitary lung lesion? What is most common?
The most common categories in the differential diagnosis areinfection, malignancy, or rheumatologic disease with the cause being dependent on risk factors for these conditions. The most commonly etiology in an alcoholic patient with dental disease is lung abscess due to anaerobes (the most common organisms are Peptostreptococcus, Prevotella, Bacteroides (usually not B. fragilis), and Fusobacterium spp). Although the majority of lung abscesses are caused by anaerobic bacteria, aerobic bacteria such as microaerophilic streptococci (eg, S. milleri), Staphylococcus aureus, and Klebsiella pneumoniae may also cause lung abscesses. For patients with cavitary lung lesions associated with an infiltrative pneumonia, the etiology is often related to those bacteria that cause necrotizing pneumonias (e.g. gram negatives, staph aureus). Lung abscess is defined as necrosis of the pulmonary parenchyma caused by microbial infection. Some use the term "necrotizing pneumonia" to distinguish pulmonary necrosis with multiple small abscesses from a larger cavitary lesion, but this actually represents a continuum of the same process. When related to pneumonias, necrotizing infections can include: anaerobic bacteria, Staph aureus, many gram negatives (e.g. pseudomonas and klebsiella), nocardia, actinomyces. Aside from necrotizing pneumonias, other infectious causes include Mycobacterial (TB and non-tuberculous mycobacterium), Nocardia and Fungal(Aspergillus, cocci, histo, blasto, crypto, PJP, mucormycosis). Also consider septic embolic in IV drug users as an infectious cause of lung abscess (especially when diffuse and small).
For elderly patients with history of smoking and weight loss, the most likely cause is cancer. In patients with autoimmune disease, granulomatosus with polyangiitis (formerly Wegener’s granulomatosus) is most common (although rheumatologic causes are less common overall than infection and malignancy).
A rare but important cause is infarction due to non-infectious embolism.
The patient receives lactulose and you are able to obtain further history from him the next day when he is more alert. He has travelled in the areas of Arizona and New Mexico, but no other travel within the US or abroad. He has no exposures to TB that he knows of. He reports a chronic cough with green sputum for 3 months with subjective fevers. He denies hemoptysis, chills, weight loss, night sweats, joint pains, or rash. He does have a 45 pack year smoking history and is currently smoking 1 ppd. He denies IVDU.
What is your initial work-up for this patient?
In this instance, would obtain blood cx, sputum cx, sputum for AFB x 3 (due to immunocompromised status), cocci Ab titers (can consider histo urinary antigen if patient ever travelled to endemic areas such as the Ohio Mississippi River Valley).
Place the patient on respiratory precautions given that TB will need to be ruled out. Review old imaging studies, ie previous CXR. Given the appearance of his teeth and the likely source of the infection, obtain a panorex and make a dental referral (inpatient vs outpatient).
Regarding imaging, expert opinion consists of (as guidelines and evidence are lacking): CT scan provides the best anatomical definition of the cavity. CT is recommended when x-rays are equivocal, cases of uncertain cause and cases that do not respond to antibiotics.Consider a chest CT in most circumstances unless the diagnosis is completely clear (alcoholic patient with obvious risk factors for aspiration, minimal to no TB risk factors, and no smoking history or weight loss/night sweats). The main purpose of obtaining a chest CT is to evaluate for other etiologies not found on CXR including associated pneumonias (and complications of pneumonias like empyema), cystic diseases, pulmonary embolism, complications of vasculitis (hemothorax). Chest CT will also further characterize the cavity to determine thickness (which increased thickness itself can be associated with higher risk of malignancy). This patient should probably have a CT given his history of smoking (to evaluate for cancer).
Review of old CXRs show this cavitary lesion was likely present for over a year and has been slowly enlarging. Given the enlargement with prior smoking history you obtain a CT Thorax. The report states:17-mm cavitary mass within the right upper lobe. This contains a focus of calcification and may be infectious or inflammatory in etiology. Consider fungal disease. Tuberculosis is not excluded. Neoplasm is not excluded. Recommend follow-up evaluation.
Sputum and blood cx, AFB x3, and cocci titers are sent and are pending.
Any additional orders/procedures? Consults?
It would be reasonable to involve pulmonary, however there is no role for bronchoscopy (unless high concern for TB or atypical presentation and want BAL to r/o TB) or drainage of the cavitary lesion. CT guided transcutaneous biopsy is also not recommended as patients usually respond to medical therapy and there is high risk of pneumothorax (IR will giggle if you ask them to biopsy a lung abscess-IR will biopsy cavitary lesions appearing as cancer).
What is your current management plan? At this point it is probably most reasonable to involve pulmonary to assist with determining the etiology of the cavitary lesion. The most likely etiology is lung abscess from anaerobes. In this instance, a biopsy is not recommended due to risk of pneumothorax and low yield of obtaining the infectious organism. The patient needs to remain inpatient to rule out the possibility of TB and will require isolation until this is complete.
You decide to treat the patient for a presumed lung abscess given the patient’s presentation with typical symptoms and risk factors (periodontal disease, alcoholism). What is your empiric treatment? What bugs do you need to cover? Do you need to drain the abscess?
Classically lung abscesses are due to anaerobic infections(as above) and are often polymicrobial. Note that sputum cultures can be misleading. Even if you cultured klebsiella, staph or strep from the sputum, treatment still needs to be directed at anaerobes.
IDSAguidelines recommend starting clindamycin 600 mg IV q 8 hours, following by 150-300 mg po QID for lung abscess. Other options are a combination of a beta-lactam/beta-lactamase inhibitor (i.e. Unaysn) or penicillin + flagyl.
Lung abscesses are the one exception to the rule that all abscesses need drainage (a review of over 2000 cases from the pre-antibiotic era in 1936 showed drainage via rigid bronchoscopy did not alter mortality). Surgery is rarely required for lung abscesses unless in the case of failure to respond to antibiotics, suspected underlying neoplasm, size >6 cm, abscess associated with obstructing bronchus, and abscesses due to resistant organisms (i.e. pseudomonas). In these cases, a lobectomy is sometimes required.
You decide to start the patient on IV clindamycin. His temperature normalizes and his cough slowly improves over the next 3 days. The AFB gram stains of the sputum and cocci studies are negative. His sputum culture grows mixed oral flora. Blood cultures are negative.
What is your plan for discharge and follow-up?
Patients usually require extended (approximately 3 months) oral antibiotic therapy (usually clindamycin). Duration is controversial. Some treat for a standard 3 weeks, others treat until radiographic improvement to clear or a small and stable residual lesion. In general, many clinicians treat for 3 months. The rationale for extended therapy is based entirely on anecdotal experience of relapse in 5 patients who were taken off therapy after 8 weeks (from a 1992 case series). Overall, 90-95% of patients respond (exception: immunosuppressed, underlying malignancy, staph or pseudomonas). Patientsshould follow-up with their PCP and Pulm or ID (no clear recommendation of frequency of follow-up needed). There is no clear recommendation for serial radiographs, but this patient should have follow-up imaging done given malignancy risk factors.
The patient is seen for follow-up in pulmonary clinic and with his PCP every 4 weeks.At 2 months his symptoms have resolved and he is taken off oral clindamycin after a repeat CXR shows resolution of the cavitary lesion and only some residual scarring.
MKSAP Questions
Infectious Disease Question 50; answer C – Empiric treatment of cavitary pnuemonia
Rheumatology Question 44; answer A – Cavitary lesions in Rheumatology
Post Module Evaluation
Please give completed evaluation to Dr. Wendy Gerstein, VAMC or Patrick Rendon, UNMH.
1) Topic of module:______
2) On a scale of 1-5, how effective was this module for learning this topic? ______
(1= not effective at all, 5 = extremely effective)
3) Were there any obvious errors, confusing data, or omissions? Please list/comment below:
______
4) Was the attending involved in the teaching of this module? Yes/no (please circle).
5) Please provide any further comments/feedback about this module, or the inpatient curriculum in general:
6) Please circle one:
Attending Resident (R2/R3)Intern/extern Medical student
Appendix:
TABLE 2 (continued)