Orbital myxoma. Report of an unusual case

Myxomas are rare, benign tumors of mesenchymal origin, which can be found in skin, heart, subcutaneous tissue and bone. Here, we describe the case of an orbital myxoma and present its clinical and imaging characteristics, as well as the surgical approach and histopathological description that led us to the diagnosis. The case involves a forty-year-old male with a 5-month history of progressive swelling in the inner third of the left lower eyelid. Previously, the patient had undergone resection of a tumor in the same region with a histopathological diagnosis of rhabdomyosarcoma. On examination a soft, mobile, painless mass was found in the inner third of the left lower eyelid that did not change with the Valsalva maneuver. Computed tomography showed a homogeneous extraconal lesion, similar to the density of the vitreous, well-defined edges, in the anterior and inferonasal portion of the left orbit. An excisional biopsy was performed, and subsequent histopathological examination showed fusiform cells without nuclear atypia and an abundant myxoid stroma. Immunohistochemistry was positive for vimentin and S-100. This led to the diagnosis of orbital myxoma. After surgery, the patient progressed well and was asymptomatic and without tumor recurrence.