Characterization of lymphoproliferative lesions of the conjunctiva: immunohistochemical and molecular genetic studies

BACKGROUND: Conjunctival lymphoproliferative lesions have not been selected for independent analysis with newer immunohistochemical and molecular genetic techniques to highlight their unique profile. METHODS: Retrospective case series examined biopsies from 16 consecutive patients with conjunctival lymphoproliferative lesions. The histopathologic, immunohistochemical, and molecular genetic features were characterized, as well as the frequency of tumour type, prognostic implications, clinical features, and treatments offered. RESULTS: The diagnosis was lymphoma in 12 cases, atypical lymphoid hyperplasia (ALH) in 1 case, and reactive lymphoid hyperplasia (RLH) in 3 cases. The primary lymphomas consisted of 4 mucosa-associated lymphoid tissue lymphomas (MALTL), 1 follicular lymphoma (FL), 2 diffuse large B-cell lymphomas (DLBCLs), 1 lymphoplasmacytic lymphoma, and 1 T-cell lymphoma. Primary lymphomas were treated with radiation (n = 7), surgery (n = 1), and topical chemotherapy (n = 1). Complete remission was achieved in 8 of 9 primary lymphomas. Two cases of recurrence to the other conjunctiva were treated with radiation and both remained disease free. Secondary lymphomas included 2 DLBCL and 1 MALTL. Complete remission was seen in 2 patients after radiation plus chemotherapy, while the patient treated with chemotherapy alone was lost to follow-up. The 1 case of ALH presented bilaterally and achieved complete remission after topical chemotherapy treatments. The 3 RLH cases were surgically managed and 2 of the 3 recurred and were subsequently excised. Eleven lymphomas were of B-cell lineage by immunophenotyping. Molecular genetic studies of immunoglobulin heavy chain (IgH) gene rearrangement by polymerase chain reaction (PCR) showed clonal bands in 6 of 12 lymphomas, 1 of 3 RLH (polyclonal by immunophenotyping) and 1 ALH. BCL2-IgH [t(14;18)] rearrangement was seen in 8 of 12 cases (1 FL, 3 DLBCLs, 4 MALTLs) by real-time quantitative PCR. INTERPRETATION: Conjunctival lymphomas are predominantly B-cell type with a high prevalence of MALTL. An unexpected finding was the BCL2-IgH rearrangement seen in 4 of 5 MALTL cases in our series. The significance of this remains unclear.