Molecular Characterization of Ocular Adenexal MALT Lymphoma
Yuki Kasama, Pan Zhang, Anjali Seth, Neena Mirani, Helen Fernandes. UMDNJ, New Jersey Medical School, Newark, NJ
Background: Extranodal marginal zone B-cell lymphoma of mucosa associated lymphoid tissue type (MALT lymphoma) is the most common type of malignant lymphoma of the ocular adenexa. Reports on the association of Chlamydia psittaci (C.psittaci) with ocular adenexal MALT lymphomas (OAML) vary geographically. Chromosomal aberrations, t(14:18) translocations and IgH clonality are often seen in OAML. We have investigated genomic alterations and immunoglobulin CDR3 sequences in a small subset of primary OAML.
Design: Nine patients with ten cases of biopsy proven ocular adenexal MALT lymphoma from over the past 10 years were selected for the study. Formalin fixed paraffin embedded tissue was used for molecular analyses. The presence of C.psittaci was determined by real time PCR with primers and FRET probes targeting the omp 1 gene. t(14:18) analysis was done by interphase FISH and IgH clonality studies were performed by capillary electrophoresis (invivoscribe). Immunoglobulin CDR3 sequences were amplified using a degenerate consensus FR3 forward primer and a reverse JH primer.
Results: All nine tissue DNA specimens were negative for C.psittaci and C trachomatis by realtime PCR. Amplification of the positive control was validated by sequencing. Cytogenetic analyses of 7 cases, showed normal karyotype in 3, deletions in 2, and multiple aberrations including trisomy 3 in 2 cases. Monoclonal populations by flow cytometry, confirmed by DNA analysis were seen in 7/9 cases. Preliminary investigations on CRD3 region did not show any sequence similarity.
Conclusions: Primary ocular adenexal MALT lymphoma shows significant molecular heterogeneity. C.psittaci was not present in the specimens investigated at our institution. CDR3 usage may be useful in determining antigenic etiology. Larger studies are necessary for determination the role of bacterial infection in the pathogenesis of the disease.
Tuesday, March 5, 2013 9:30 AM
Poster Session III # 219, Tuesday Morning