Abstract
PURPOSE: To describe an orbital myeloid sarcoma in adult presenting with a swollen mass at inferomedial canthal area and epiphora which was misdiagnosed as nasolacrimal duct obstruction. OBSERVATIONS: A 45-year-old male presented with a swollen right lower eyelid around medial canthal area for 2 months with tearing for 6 month-period earlier. Eye examination demonstrated a high tear meniscus, slightly erythematous eyelid with palpable mass closed to the lacrimal sac along the inferior orbital rim. Computed tomography scan depicted infiltrative mass at the inferomedial aspect of right orbit with bony erosion, extended to adjacent paranasal sinuses. An incisional biopsy was performed. Histopathological study revealed soft tissue which was diffusely infiltrated by monotonous medium-sized round cells resembling blasts with lymphoglandular bodies, focally positive myeloperoxidase and negative lymphoid markers. The findings were consistent with myeloid sarcoma. No systemic involvement was found. The patient underwent chemotherapy and radiation without systemic leukemic disease progression. CONCLUSIONS AND IMPORTANCE: Although orbital myeloid sarcoma is rare and difficult to diagnose, it can mimic nasolacrimal duct obstruction. We should consider this condition in our differential diagnosis.