| Abstract
| - Aim:. To report well-circumscribed orbital lymphatic-venous malformations (VLMs) with atypical clinical, imaging and pathological features in four paediatric patients. Methods:. Retrospective non-comparative case series of four patients aged 5-18 years old having a well-circumscribed orbital mass diagnosed histopathologically as orbital VLM. All patients underwent orbitotomy and total excision of the VLM. Pre- and postoperative visual acuity, proptosis and globe displacement produced by the orbital VLM, MRI findings, histopathological features, treatment, follow-up and prognosis were evaluated. Results:. No proptosis, visual acuity change or globe displacement was induced by the orbital VLM. One lesion was located superiorly, one medially and two inferonasally. On MRI, the orbital VLMs were isointense on T1-weighted images and hyperintense on T2-weighted images, demonstrated moderate contrast enhancement and had a heterogenous internal structure. Signal void areas and fluid-fluid levels were not observed on MRI. At a mean follow-up of 50 months, all patients remained free of recurrence clinically and retained preoperative visual acuities. Several histopathological features of the excised lesions supported an initial diagnosis of cavernous haemangioma, but the lesions were subsequently rediagnosed as orbital VLM when aggregates of lymphocytes and randomly arranged smooth muscle were noted. Conclusions:. Well-circumscribed orbital VLMs in children can display atypical clinical, imaging and pathological features. MRI features of this entity are not characteristic of typical orbital VLMs. It may be possible to totally excise well-circumscribed orbital VLMs as in this series of four patients. Careful histopathological evaluation indicates the correct diagnosis.
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