Free-floating cyst in the anterior chamber: ultrasound biomicroscopic reports

PURPOSE: To report a free-floating dislodged pigmented cyst in the anterior chamber and to describe the ultrasound biomicroscopic (UBM) features of the lesion. METHODS: Case report. RESULTS: A 26-year-old man presented with noise in his left eye in the prone position. Slit-lamp examination revealed a small pigmented mass lesion at the 6 o'clock position in the anterior chamber, slowly moving with changing head postures. UBM revealed an unfixed dislodged pigmented cyst with a thin wall and no internal reflectivity, changing its shape from ovoid to circular. Five years later, the anterior segment does not show any modification and the cyst has not changed in size or appearance. CONCLUSIONS: Cysts of the iris pigment epithelium arise in the posterior iris layer. They may be central, midzonal, peripheral, or dislodged. Dislodged cysts may be repositioned and fixed or free-floating in the vitreous or in the anterior chamber. Surgical removal must be considered only for a rapid enlargement or significant reduction in endothelial cell count. UBM can distinguish solid from cystic lesions, giving detailed information on internal structure, reflectivity, shape, and thickness.