Teaching Case

Right eye proptosis in female child.

Female patient presenting with proptosis of the right eye. The examination of the eye did not show any other abnormality in the right eye and in the controlateral side. CT and MRI of the orbits were performed after ophtalmologist consultation, which suggested the possibility of an orbital mass of unknown origin. CT was performed first, as this technique is more widely available, and can clarify the nature of an orbital mass in the majority of cases. CT of the orbits is performed usually in the axial plane (imaging in the coronal plane is possible if needed) with 3 mm slice thickness and i.v administration of iodinated contrast medium. Axial 3 mm CT sections allow clear visualization of the globe, the optic nerve and orbital muscles. The presence of retroorbital fat allows a good distinction between the normal components of the orbit and soft tissue masses, and calcifications within an orbital mass (whose presence is often crucial in the differential diagnosis) ares readily seen with CT. MRI has the advantage of providing a multiplanar approach to any part of the body, and it is often helpful to surgeons, as it was felt in this case.

Lymphangiomas are benign hamartomatous tumours usually diagnosed in early childhood involving in 20% of cases the orbit and ocular adnexa; they account for less than 2% of orbital biopsies. Lymphangiomas present clinically with a slowly progressive proptosis, displacement of the globe, ptosis, and restriction of eye movements. Spontaneous intraorbital haemorrhage may cause acute proptosis, compressive optic neuropathy, and loss of the vision. Amblyopia may develop in children with marked ptosis. In a patient series by Tunc et al., all patients who had a final visual acuity <20/40 were under 6 years old at presentation with ptosis and/or strabismus. The nature of these tumors is uncertain: some are in continuity with the venous circulation; rarely, they can be associated with an arteriovenous malformation but most do not have radiological evidence of a vascular connection. Several authors have questioned the validity of the term orbital lymphangioma and believe that all of these tumefactions are variants of venous malformations. In contrast with their benign histology, these tumours have a locally aggressive nature. The histological pattern of orbital lymphangioma is characteristic; however there are overlapping factors with other orbital vascular abnormalities. Most of the lesions had thin walled stroma; a single layer of sometimes discontinous flat epithelium, and lymphoid infiltration. Lymphoid cells aggregating in the subendothelial space are sometimes present, as well as was haemorrhagic material in cystic spaces. As some authors have noted, fibrosis is present in around half of our cases, probably as a result of repeated haemorrhages. Their radiological appearance may mimic other tumours and their histological features may overlap with orbital vascular anomalies. The main radiological features are the presence of an orbital mass in a child aged usually from 0 to 10 years, with variable proptosis without spontaneous resolution. The orbital lymphangioma has commonly a preseptal or extraconal location, withou bone erosion. It is isodense with low contrast enhancement on CT, and it shows a heterogeneous signal intensity with variable contrast enhancement on MRI. The radiological differential diagnosis is with other orbital masses seen in children: optic nerve glioma (which is seen in children below 10 years of age, but has intraconal growth and shows intense contrast enhancement in CT), rhabdomyosarcoma (which often expands intracranially and/or with bone destruction), leukamia (often bilateral, and seen in children > 10 years usually), cellulitis and pseudotumor (often correlated to clinical symptoms, such as pain, fever, etc). Lymphangiomas are hamartomatous malformations with normal cell replication cycle. Some researchers believe that venous lymphatic shunts are important in the development of these lesions since lymphatic channels grow in association with the venous plexa during the embryonic life. Other authors believe lymphangiomas are haemodynamically isolated vascular hamartomas. Management of orbital lymphangioma can be difficult and surgery remains the treatment of choice. Carbon dioxide laser is a useful adjuvant therapy in selected cases. A few patients have been treated with other modalities including irradiation or sclerosing agents. In symptomatic patients the infiltrative, diffuse nature of the lesion usually allows only a partial resection. In lymphangioma the main goal of the treatment is preservation of visual function and cosmesis.