Lymphoid tumor in the orbit: malignant or benign? MRI, histomorphological and molecular genetic analysis of eight cases

Differentiation between benign and malignant lymphoid infiltrates of the conjunctiva and the orbit is difficult even on the basis of histopathological appearance. We describe eight cases with low-grade malignant lymphoma, mucosa-associated lesion tissue (MALT) lymphoma. Laboratory analysis was done using microscopy, immunophenotyping and gene rearrangement using the Southern blot technique. DNA-rearrangement analysis allows a very precise determination of the benign and malignant lymphoid infiltrates of the ocular region. Our MRI findings show that these tumors can also generally be distinguished by their signal intensity on T2-weighted images. These findings might explain the favorable prognosis for MALT lymphoma of the conjunctiva and the orbit, and the absence of any recurrence in follow-ups ranging from 6 months to 9 years.