Isolated periocular myeloid sarcoma misdiagnosed as anterior scleritis

The authors describe the case of a right eye sub-conjunctival lesion, initially misdiagnosed and treated as anterior scleritis, in a female patient in her early twenties. The lesion showed nearly complete clinical resolution on initial treatment with oral steroids. The lesion recurred, however, after discontinuing oral steroids, and at the subsequent visit, the lesion was more widespread and elevated. Anterior-segment optical coherence tomography showed a sub-conjunctival lesion, and CT scan of the orbits showed an isodense periocular lesion moulding around the globe. Crush artefacts prevented accurate histopathological interpretation of the initial incisional biopsy. The patient developed right eye chemosis, proptosis and extraocular motility limitation. Repeat incisional biopsy revealed myeloid sarcoma based on immunohistochemistry. Bone marrow and peripheral blood smears were normal. A whole-body positron emission tomography-computed tomography scan showed hypermetabolic activity in the right periocular area alone. The patient was treated with intravenous chemotherapy, leading to complete tumour resolution.