Diagnostic incisional biopsies in clinically indeterminate choroidal tumours

Most intraocular tumours are reliably diagnosed by a careful clinical examination combined with one or more non-invasive diagnostic techniques. However, in a small percentage of tumours, typically small and clinically amelanotic, the features are insufficiently distinct for a confident clinical diagnosis and tissue is required for diagnosis. We used a 23-G vitreous cutter to access the biopsy site in 43 patients with clinically indeterminate tumours. After retinotomy, an incisional choroidal biopsy yielded a specimen of ∼1 mm(3). Obtained tissue was routinely processed for light microscopy including an immunohistochemical panel of monoclonal antibodies. Adequate tissue for diagnosis was provided in 41/43 (95%) patients. The sensitivity and specificity to detect malignant disease were 0.97 and 1.00, respectively. The positive predictive value was 1.00. Complications included progression of pre-existing retinal detachment in 5/43 (12%) patients and transient rise in intraocular pressure to >40 mm Hg in 6/43 (14%) patients; 4 of these 6 patients had a pre-existing retinal detachment. No patient with a pre-operatively attached retina had a retinal detachment. We conclude that an incisional transretinal choroidal biopsy yields abundant material and may adequately confirm or exclude malignancy in patients with clinically indeterminate tumours. The complication rate can be minimised when patients with pre-existing retinal detachment are excluded from biopsy.