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.