Conjunctival Stromal Tumor: Anterior Segment Optical Coherence Tomography, In Vivo Confocal Microscopy, and Pathological Findings

A 38-year-old woman presented with a visible conjunctival mass in the right eye. Anterior segment examination revealed a red, painless, and elevated lesion on the temporal bulbar conjunctiva in the right eye. Anterior segment swept-source optical coherence tomography (AS SS-OCT) showed a subepithelial hyperreflective mass with a hyporeflective transition zone separating the lesion from the underlying tissues. In vivo confocal microscopy (IVCM) demonstrated scattered and disorganized hyperreflective collagen fibers in the lymphoid stromal layer and dense meshwork of collagen fibers, dilated vessels, and Langerhans cells in the fibrous stromal layer. After excisional biopsy of the lesion, histopathological examination revealed that the lesion consisted of spindle cells with occasional nuclear pseudoinclusions in a background of scattered collagen fibers, with no atypia and mitosis. Spindle cells showed diffuse staining for vimentin and CD34 and no staining for S-100, EMA, and SMA. Some spindle cells stained positive for factor XIIIa. Few KIT positive mast cells and CD68 positive histiocytes were also observed. Ki-67 proliferation index was 2% to 3%. These findings were consistent with the diagnosis of conjunctival stromal tumor (COST). This case report highlights the AS SS-OCT and IVCM findings in a rare example of COST. Histopathology and immunohistochemistry findings still remain the gold standard for diagnosis.