Objective: To evaluate the usefulness of transthoracic needle biopsy (TNB) for the diagnosis of bronchial carcinoma underlying lung abscess (LA), and to determine the bacteriology of lung abscess secondary to neoplasm (LASN).
Patients and method: One hundred thirteen consecutive patients diagnosed of LA were enrolled. Radiologically guided TNB was performed on all patients using 20-22 G needles. Microbiological and cytological samples were processed. Fiberoptic bronchoscopy (FB) was performed if there were risk factors for lung cancer. TNB-diagnosed cases were compared with the remaining cases of LA.
Results: Neoplasia was found in 21 LA patients. TNB samples provided diagnostic information in 15 cases, there were 2 false negatives, and no cytology sample was processed in 4 cases. Diagnosis was based on FB in 17 cases. All neoplasias were diagnosed with one technique or the other. TNB culture was positive in 90% (19/21) of the LASN patients, H. influenzae being the most frequently isolated bacterium. The number of cultures that presented a single microbe was significantly greater (p < 0.02) among LASN patients (14/19 versus 33/79). These patients also had significantly more aerobic bacteria (19/19 versus 45/79; p < 0.001) and fewer anaerobies (4/19 versus 52/79; p < 0.001) than did the primary LA patients.
Conclusions: 1) TNB is highly useful for arriving at a bacteriologic diagnosis of LASN and in associated cancer. 2) TNB complements FB for the diagnosis of neoplasia underlying LA and helps to reduce the number of unnecessary thoracotomies. 3) A great variety of germs, particularly aerobic bacteria, are implicated in LASN.