Value of radiologically guided fine needle aspiration cytology (FNAC) in the diagnosis of spinal tuberculosis: a study of 29 cases

FNAC is a simple diagnostic tool for the initial evaluation of various deep seated pathological lesions. This study describes the applicability and pr actical aspects of the technique in establishing the diagnosis of spinal tu berculosis (TB) with the aid of radiographic guidance. The study was conduc ted in a major teaching hospital in Kuwait between the years 1985 and 1994. Twenty-nine patients (M:F = 18:11 and age range 8-72 years) with clinicall y and/or radiologically suspected spinal TB were seen in the Department of Cytology, Mubarak Al Kabeer Hospital. The patients were re-examined by eith er computed tomography (CT) scanning (n = 19) or fluoroscopy (n = 10) to lo calize the lesion for FNAC. FNAC smears were routinely stained with Papanic olaou and Diff Quik stains and one smear of each case was stained with Zieh l-Neelsen (Z-N) stain for acid-fast bacilli (AFB). Aspirated purulent mater ial or syringe washings of dry aspirates were also submitted for microbiolo gical cultures including AFB. Radiological and cytological findings were re corded in each case. Radiological findings included: bony rarefaction and d estruction (93.1%), narrowed disc space (89.7%), soft tissue calcification (65.5%) and para-vertebral abscess formation (51.7%). Cytological findings included: epithelioid cell granulomas (89.7%), granular necrotic background (82.8%) and lymphocytic infiltration (75.9%). Smears were positive for AFB in 51.7% of cases. A positive AFB culture was obtained in 82.8% of cases, including all cases with positive AFB on smear by Z-N stain. Radiologically guided FNAC with AFB culture is a simple, reliable and practical approach to diagnosing spinal TB lesions. With a high diagnostic yield, it allows im mediate initiation of specific treatment, helps to avoid invasive diagnosti c procedures, and decreases hospitalization time.