A prospective comparison of fine-needle aspiration cytopathology and histopathology in the diagnosis of orbital mass lesions.

AIM: To assess the diagnostic value of the orbital fine needle aspiration biopsy (FNAB) with an in vitro technique, eliminating the sampling error.
DESIGN: Prospective, non-randomised, interventional case series.
METHODS: Sixty-eight patients were studied prospectively in institutional clinical practices. Immediately after excision of orbital mass lesions, the removed tissue was stabilised under the hand of the surgeon and biopsied with a 23- or 25-gauge needle. The samples were processed for cytopathological examination with Cytospin. The excised specimens were then submitted for routine histological examination. The cytopathological diagnoses were compared with the final histopathological diagnoses.
RESULTS: Six out of 68 lesions were excluded and the remaining 62 cases were divided into four groups as primary malignant, primary benign, secondary malignant and inflammatory lesions, based on histopathological diagnoses. In 43 cases the cytopathological and histopathological diagnoses were the same, with a concordance rate of 69%. Among the malignant tumours, the cytopathological diagnoses correlated with the histopathological diagnoses in 14/14 and 17/27 cases of metastatic/secondary and primary orbital malignancies, respectively. Of 11 primary benign tumours, two cytopathological diagnoses correlated with histopathology. In inflammatory lesions, the cytopathological diagnoses were matched with the histopathological diagnoses in 10/10 biopsies.
CONCLUSION: Even when the sampling error is eliminated with an "in vitro FNAB" technique, the concordance rates between histopathological and cytopathological diagnoses varied considerably among different types of orbital mass lesions. FNAB diagnoses were most reliable in metastatic and secondary malignancies and inflammatory lesions, and least reliable in benign orbital neoplasms and cysts.