Severe exophthalmos secondary to orbital myopathy not due to Graves's disease

An 18-month-old white female child presented with severe bilateral exophthalmos. She was thought to have Grave's disease because her orbital CT scan showed massively enlarge extraocular muscles. She was subsequently found to have myelomonocytic leukaemia. This was treated with radiation, with rapid resolution of her exophthalmos and exposure keratitis.