Plentiful melanin pigment containing histiocyte-like cells in Coats disease: Awareness avoids diagnostic pitfall.

Coats disease is an exudative retinal vasculopathy characterised by presence of yellow-golden deposits in the retina and retinal detachment. Subretinal fluid drainage performed as a part of therapeutic management makes the fluid amenable to cytological examination. Infection by Toxoplasma may closely simulate the ocular symptoms seen in Coats disease. Awareness of the cytological findings in Coats disease helps to clinch accurate diagnosis. We herein present a case of Coats disease with many histiocyte-like cells with plentiful intracytoplasmic melanin pigment in cytology smears from subretinal fluid, where cytological diagnosis was challenging and a correct diagnosis was made with the aid of ancillary techniques.