Background : Coats’ disease is an exudative retinal detachment with vascular telangiectasis occurring mostly in male children, the age group most affected by retinoblastoma. Objectives : To compare the differential diagnoses of Coats’ disease. To establish recommendation to early disease detection. Materials and Methods : A 3-year-old female child was referred to Muhimbili National Hospital (MNH), Tanzania, in September 2011. She had presented at the peripheral hospital with gradual onset of left eye leukocoria for 1 year and pain for 2 months. B-scan showed a mass in the left eye. A clinical diagnosis of retinoblastoma was made. Left eye enucleation was performed; the patient was referred to MNH, with the enucleated specimen. Results : Brain and orbits scan revealed no residual tumour. The globe measured 2x1.8 cm, the optic nerve stump measured 3 mm. A whitish mass filled the vitreous, with complete retinal detachment. Microscopy showed retinal gliosis, detachment with sub retinal PAS positive exudates, vacuolation and cholesterol clefts. Foreign body giant cells were present; telangiectatic thin-walled blood vessels were identified. Clinico-pathological findings were of stage 4 Coats’ disease. Conclusion : Coats’ disease is an important differential diagnosis of retinoblastoma. Delay to detect Coats’ disease leads to vision loss which necessitates eye enucleation as was in this child.

Keywords : Coats’ disease, Tanzania