Purpose: To determine the efficacy of transvitreal biopsy in the diagnosis of suspected intraocular malignancy and simulating conditions.
Methods: We performed a retrospective study of the case notes from patients who underwent pars plana transvitreal biopsy from July 1986 to October 1999. We studied the relationship between lesion thickness as measured by A-scan ocular ultrasound and the incidence of a successful diagnostic biopsy. We assessed the diagnostic accuracy by comparing the biopsy result with the histological examination of any subsequently enucleation specimens and noted the incidence and severity of complications attributable to the biopsy.
Results: A total of 83 biopsies were performed for choroidal masses. There was insufficient material for cytological examination in 10 cases, and sufficient material in 73 cases (an overall diagnostic report rate was 88%). There was a strong correlation (p = 0.0004, Mann-Whitney U-test) between a diagnostic biopsy result and the thickness of the lesion on A-scan ultrasound: a biopsy was diagnostic in only 40% (4 of 10) of choroidal lesions less than 1.99 mm thick, whereas biopsies taken from lesions between 2.00 and 4.00 mm thick were diagnostic in 90% of cases (27 of 30). In thicker lesions of 4 mm or more the cell aspirate was sufficient to make a diagnosis in 98% (42 of 43). Following diagnostic biopsy 27 patients had their tumours resected, and the histology results following enucleation confirmed the cytological diagnosis of malignancy in 96% of these cases (26 of 27).
Conclusion: Transvitreal biopsy is a highly accurate diagnostic procedure with a low complication rate. It is a reliable diagnostic tool in suspicious choroidal lesions greater than 2 mm thick.