IgH Gene Rearrangement Analysis in Ocular Lymphoma

Abstract

Abstract: : Purpose: Primary intraocular lymphoma (PIOL) is a rare malignancy. The diagnosis, mainly based on morphological analysis of vitreous material obtained through pars–plana vitrectomy (PPV), is made difficult by the low cellularity and the friability of lymphocytes within the vitreous sample. Immunoglobulin heavy chain gene rearrangement analysis (IGHR) has been used as an adjunct to cytopathology and flow cytometry in systemic lymphoma but experience in PIOL is limited to a few case reports. Our purpose is to determine the sensitivity and specificity of IGHR in the diagnosis of intraocular lymphoma. Methods: We reviewed the clinical records of patients who underwent PPV for suspicion of PIOL at the Immunology and Uveitis Service of the Massachusetts Eye and Ear Infirmary from 2000 to 2002. Less than 0.5 ml of vitreous fluid or the vitreous wash samples were obtained for IGHR analysis. Cells were separated by centrifugation. The cell pellet was resuspended in 100 µl of the supernatant and boiled for 10 minutes. The lysate was used for polymerase chain reaction (PCR). Amplification was performed by semi–nested PCR using consensus primers for the V– and J–region of the IgH gene. PCR products were separated on a 10 % polyacrylamide gel. The gel was stained in ethidium bromide and photographed on an ultraviolet light screen. Clonal rearrangement was defined as the occurrence of identical bands in PCR assays of at least two aliquot of the same specimen. Results: 60 vitreous specimens were received and analyzed with IGHR analysis; 37 specimens were negative for malignancy and 23 specimens were positive for IOL. Using the patients’ clinical course as the "gold standard" for the diagnosis of lymphoma versus an inflammatory process, specificity of vitreous fluid cytopathology, flow cytometry and IGHR was 94.3 %, 65.7 % and 100 %, respectively. Sensitivity was 59.1 %, 19.0 % and 44.4 % respectively. The combination of all diagnostic tests increased diagnostic sensitivity to 76 %. Conclusions: There is no ideal single diagnostic test for the distinction of intraocular lymphoma from inflammatory conditions affecting the eye. IGHR, supplementing cytopathology and flow cytometry, is a useful tool to distinguish ocular neoplastic disease from reactive proliferations of lymphocytes. Since clonal rearrangement of IgH is only a marker of clonality and not of malignancy, correlation of PCR data with clinical presentation as well as morphological and immunohistochemical data is indispensable.

Keywords: oncology • uveitis–clinical/animal model • vitreous