The approach to nonresolving pneumonia

Bronchoalveolar carcinoma (adenocarcinoma) mimicking recurrent bacterial community-acquired pneumonia (CAP)

Depending on the community-acquired pneumonia (CAP) pathogen, host factors, and immune status, CAPs resolve on chest x-rays at different rates. CAPs that resolve more slowly than expected, or not at all, are termed "slowly or non-resolving CAPs." In contrast, recurrent CAPs may be due to host defense defects (eg, multiple myelomas) or post-obstructive bronchogenic carcinomas. There are a variety of noninfectious disorders that may mimic CAPs on chest x-ray: alveolar hemorrhage, pulmonary drug reactions, radiation pneumonitis, Wegener's granulomatosis, bronchiolitis obliterans organizing pneumonia, bronchogenic carcinomas, and lymphomas. Noninfectious mimics of recurrent CAPs include congestive heart failure, pulmonary emboli, infarctions, sarcoidosis, and systemic lupus erythematosus pneumonitis. We present the case of a middle-aged man who presented with recurrent right middle lobe and right lower lobe CAPs. Diagnostic bronchoscopy showed no bronchial obstruction, but open lung biopsy showed bronchoalveolar carcinoma (well-differentiated adenocarcinoma). Bronchoalveolar carcinomas presenting as post-obstructive or recurrent CAPs are rare because the spread is along tissue planes and not endobronchially. The case described demonstrates a rare cause of bronchogenic carcinoma mimicking recurrent CAP.

CT-guided biopsy of nonresolving focal air space consolidation

OBJECTIVES

To evaluate the diagnostic accuracy of percutaneous computed tomography (CT)-guided coaxial core needle biopsy in patients with nonresolving pulmonary focal air space consolidations and negative fiberoptic bronchoscopy results.

METHODS

From 1997 to 2005, 23 patients (11 woman, 12 men; age range, 45 to 81 y; mean age, 66 y) presenting with nonresolving pneumonia persisting more than 8 weeks (mean, 22 wk; range, 8 to 40 wk) with negative fiberscopic results, underwent coaxial percutaneous biopsy using an automated core needle (18-gauge) under CT guidance. Histologic and bacteriologic evaluations were obtained. The final diagnosis was confirmed by surgical pathology, culture results, or clinical follow-up.

RESULTS

Specimens adequate for histopathologic evaluations were obtained in 20 (87%) cases. Final diagnoses were lung cancer (n=15) and benign diseases (infectious pneumonia, 3; lipoid pneumonia, 1; Erdheim Chester disease: 1; and nonspecific chronic pneumonia, 3). Diagnostic yield of core needle biopsy was 78% (18 of 23). The sensitivity and specificity for malignancy were 87% and 100%, respectively. Immediate pneumothorax was present in 11 patients of cases, but only 2 patients required pleural drainage.

DISCUSSION

CT-guided lung biopsy using a core needle biopsy provides a high degree of diagnostic accuracy and allows specific characterization of nonresolving pulmonary focal air space consolidation.

Non-infectious and unusual infectious mimics of community-acquired pneumonia

Noninfectious or unusual infectious diseases may present with clinical, radiological and laboratorial characteristics of community-acquired pneumonia (CAP). Usually their presence is only suspected after treatment failure, leading to inappropriate interventions, unnecessary costs and risks related to the untreated potentially life-threatening disease. The present study aimed to assess the noninfectious or unusual infectious diseases that may be misdiagnosed as CAP that progresses with treatment failure. Sixteen hospitalized patients with presumptive diagnosis of CAP and treatment failure were described. The most prevalent symptoms were fever and cough. Radiological pattern of air-space disease was observed in 10 (62%) patients. The diagnosis was established by autopsy (12%) or invasive procedures (88%), as follows: open lung biopsy (nine), flexible fiberoptic bronchoscopy (two), transthoracic fine needle aspiration (two) and bone marrow aspiration (one). Eight patients had noninfectious diseases: pulmonary embolism, cryptogenic organizing pneumonia, Wegener's granulomatosis, hypersensitivity pneumonitis, bronchocentric granulomatosis, neoplastic disease and acute leukemia. The unusual infectious diseases were: tuberculosis, cryptococcosis, actinomycosis, histoplasmosis and paracoccidioidomycosis. Patients with noninfectious or unusual infectious diseases may present with symptoms and radiological findings that mimic CAP. These diseases should always be suspected in patients who do not respond to initial empirical antimicrobial treatment, especially young patients or those without comorbidity.

Community-acquired pneumonia: causes of treatment failure in patients enrolled in clinical trials

In order to determine the causes of treatment failure in community-acquired pneumonia (CAP) clinical trials, a MEDLINE search for all CAP studies published between 1990 and 1997 was performed. Prospective, randomized studies comparing the efficacy of two or more antibiotics in CAP were selected. Treatment failure was defined as persistent fever, deterioration of patient's condition, or a change in the prescribed antibiotic regimen. In 16% of the cases included in the clinical trials, the treatment of CAP is unsuccessful. A significant number of identified failure cases were owing to antibiotic side-effects. Resistant pathogens are an unusual cause of failure whatever the antibiotic used.

Nonresolving or slowly resolving pneumonia

Given the variability in rate of radiographic resolution, it remains controversial to decide when to initiate an invasive diagnostic work-up for nonresolving or slowly resolving pulmonary infiltrates. In immunocompetent patients who present with classical features of CAP (i.e., fever, chills, productive cough, new pulmonary infiltrate), clinical response to therapy is the most important determinant for further diagnostic studies. Within the first few days, persistence or even progression of infiltrates on chest radiographs is not unusual. Defervescence, diminished symptoms, and resolution of leukocytosis strongly support a response to antibiotic therapy, even when chest radiographic abnormalities persist. In this context, observation alone is reasonable, and invasive procedures can be deferred. Serial radiographs and clinical examinations dictate subsequent evaluation. In contrast, when clinical improvement has not occurred and chest radiographs are unchanged or worse, a more aggressive approach is warranted. In this setting, we advise fiberoptic bronchoscopy with BAL and appropriate cultures for bacteria, legionella, fungi, and mycobacteria. When endobronchial anatomy is normal and there is no purulence to suggest infection, TBBs should be done to exclude noninfectious causes (discussed earlier) or infections attributable to mycobacteria or fungi. An aggressive approach is also warranted in patients who are clinically stable or improving when the rate of radiographic resolution is delayed. As discussed earlier, what constitutes excessive delay is controversial, and depends upon the acuity of illness, specific pathogen, extent of involvement (i.e., lobar versus multilobar), comorbidities, and diverse host factors. Stable infiltrates even 2 to 4 weeks after institution of antibiotic therapy does not mandate intervention provided patients are improving clinically. Invasive techniques can also be deferred when unequivocal, albeit incomplete, radiographic resolution can be demonstrated. Lack of at least partial radiographic resolution by 6 weeks, even in asymptomatic patients, however, deserves consideration of alternative causes (e.g., endobronchial obstructing lesions, or noninfectious causes). Fiberoptic bronchoscopy with BAL and TBBs has minimal morbidity and is the preferred initial invasive procedure for detecting endobronchial lesions or substantiating noninfectious causes. The yield of bronchoscopy depends on demographics, radiographic features, and pre-test likelihood. In the absence of specific risk factors, the incidence of obstructing lesions (e.g., bronchogenic carcinomas, bronchial adenomas, obstructive foreign body) is low. Bronchogenic carcinoma is rare in nonsmoking, young (< 50 years) patients but is a legitimate consideration in older patients with a history of tobacco abuse. Non-neoplastic causes (e.g., pulmonary vasculitis, hypersensitivity pneumonia, etc.) should be considered when specific features are present (e.g., hematuria, appropriate epidemiologic exposures). Ancillary serologic tests or biopsies of extrapulmonary sites are invaluable in some cases. In rare instances, surgical (open or VATS) biopsy is necessary to diagnose refractory or non-resolving "pneumonias."