Acute myeloid leukaemia presenting as gaze palsy

The most frequent initial ocular manifestation of acute myeloid leukaemia (AML) is retinal involvement. Here, we report an unusual case of AML associated with a pontine chloroma presenting with gaze palsy as the initial symptom. A 77-year-old Caucasian man presented to the Eye Casualty complaining of a one-day history of blurred vision. On examination, his face was turned to the left, both eyes were fixed in dextroversion and the patient demonstrated left gaze palsy associated with left motor neurone VII palsy. Baseline blood investigations revealed leucocytosis with 60% circulating myeloblasts. A bone marrow biopsy confirmed the diagnosis of myelomonocytic leukaemia. A CT scan showed a well-circumscribed lesion in the dorsal pons, most likely representing a chloroma. Chloromas or myeloblastomas related to AML are localised extramedullary tumours composed of leukaemic myeloid cells. Chloromas may be present at the time of the initial diagnosis of leukaemia or may precede the diagnosis by 1 month to 2 years; however, their occurrence in the central nervous system is rare, comprising 1-6% of all chloromas. This case illustrates the many different ways that AML can manifest itself in the eyes, and ophthalmologists should be aware of the great variety of presenting symptoms in undiagnosed AML.