The value of microbial cultures in diagnostic lymph-node biopsy

Microbial cultures were performed on 163 lymph-node biopsies from a variety of sites and in all age groups. Growth occurred in 76 (47%), 41 of which were considered contaminants. The final diagnoses were as follows: mycobacterial infection (27 biopsies), coccidioidomycosis (two cultures), nonspecific inflammatory changes (82 cultures), malignancy (51 cultures), and Whipple's disease (one culture). Microbial culture was the sole means of diagnosing nine cases of mycobacterial infection. The fluorescent stain demonstrated acid-fast bacilli in only 16 biopsies, twice the frequency with the standard Ziehl-Neelson stain. Other bacterial isolates were of uncertain significance in most instances. Routine culture for mycobacteria and fungi is recommended for all lymph nodes that show granulomatous changes.