Is fine needle aspiration cytology a useful tool for the diagnosis of tuberculous lymphadenitis?

OBJECTIVE

To study the role of fine needle aspiration cytology (FNAC) in the diagnosis of tuberculous lymphadenitis and find a place for FNAC as laboratory diagnostic method in tuberculosis (TB) control programmes.

DESIGN

Prospective laboratory study.

METHOD: Duplicate smears from 127 lymph node aspiration were prepared. Both slides were air-dried. Giemsa stain for cytological examination and Ziehl-Neelsen stain for demonstration of acid fast bacillus(AFB) were used and examined by a pathologist and laboratory technologist respectively.

SETTING

Tigrai Regional Health Research and Laboratory Centre which is the only unit with microbiological and cytopathological service in the region.

SUBJECTS: Patients with one or more enlarged lymph nodes who were sent for FNAC were included.

RESULTS

The AFB positivity among the cytologically diagnosed cases of TB lymphadenitis was 56.77%. If we had used culture media for Mycobacterium spp, the positivity would have probably been higher. The positivity rate varied depending on the type of the aspirate. Caseous aspirate showed a higher positivity rate of 60.47% whereas no AFBs were detected in haemorrhagic aspirates.

CONCLUSION

This study has demonstrated the usefulness of FNAC in the diagnosis of TB lymphadenitis and the national TB and leprosy control programmes should encompass FNAC as a diagnostic means instead of biopsy which is more invasive and costly.