Clinical and radiological presentation of 95 orbital lymphoid tumors

Background: Although most orbital lymphoid tumors are characterized by a slow, painless onset and a mass that molds to orbital structures, different presentations may occur. Intensity on T2-weighted MRI is a possible means for differentiating lymphoid tumors (hyperintense) from pseudotumors (hypointense). In addition, it is generally assumed that 75% of orbital lymphomas are at stage I on presentation. Methods: The clinical, CT, and MRI presentation of 95 primary and secondary orbital lymphoid tumors (63 non-Hodgkin lymphomas and 32 lymphoid hyperplasias) and their histological grade and staging were reviewed. Immunohistochemistry and PCR were used to determine clonality. Results: No significant differences were found between non-Hodgkin lymphomas and lymphoid hyperplasias, except for the mean age of the patients (6.3 years older in non-Hodgkin lymphomas). In both groups the most common presentation was a mass with an indolent course; visual impairment was seen in 13%, conjunctival redness in 25%, pain in 12%, and acute orbital inflammation in 15% of the patients. In most cases, the CT showed one or more lobulated or rounded masses, molding to adjacent structures, or a wedge-shaped enlargement of the lacrimal gland. Intramuscular lymphomas were rare and always associated with extramuscular masses. On T2-weighted MRI, only 35% of lymphoid tumors were hyperintense. Only 49% of lymphomas were at stage I on presentation. Conclusion: An inflammatory presentation is not uncommon orbital lymphoid tumors. Shape, molding and multiple masses can help radiological diagnosis, whereas MRI T2 intensity is unreliable. Accurate staging can disclose systemic disease in more than 50% of cases of non-Hodgkin lymphoma.