Helicobacter pylori (H. pylori) molecular signature in conjunctival mucosa-associated lymphoid tissue (MALT) lymphoma

Abstract

Conjunctival mucosa-associated lymphoid tissue (MALT) lymphoma is an extranodal marginal zone B-cell lymphoma that is characterized by an exaggerated clonal expansion of B cells, which implicate a pathological proliferative response to antigen(s) including bacteria. Helicobacter pylori (H. pylori) infection is recognized as one of the causative agents of gastric MALT lymphoma; however, it has not been reported in extra gastric MALT lymphoma. We studied 5 patients (4 adults and 1 child) with salmon-colored conjunctival lesions. One patient also had a history of abnormal bone marrow biopsy a year earlier with lymphoid aggregates involving 5% of the overall bone marrow. The conjunctival lesions of the 5 patients were biopsied. Histopathological diagnoses were consistent with conjunctival MALT lymphoma. Lymphoma and normal conjunctival cells were microdissected using laser capture microscopy or manual techniques. DNA was extracted and subjected to PCR amplification using H. pylori gene-specific primers from the urease B and vac/m2 gene. Cells from chronic conjunctivitis (normal lymphocytes), conjunctival human T-cell lymphotropic virus type-1/adult T-cell leukemia/lymphoma (HTLV-1/ATL), and orbital B-cell lymphoma were also microdissected, processed and analyzed. PCR amplification and Southern blot hybridization demonstrated H. pylori DNA in the conjunctival MALT lymphoma cells of 4/5 cases. The negative case was the one with a history of abnormal bone marrow. In contrast, H. pylori gene was not detected in normal conjunctival cells from the cases of MALT lymphoma or the lymphocytes, ATL and orbital B-lymphoma cells from the controls. These data suggest that H. pylori may play a role in conjunctival MALT lymphoma.

Fig. 1

Photomicrographs showing well-demarcated MALT lymphoma infiltration in the substantia propria beneath or invading the conjunctival epithelium in Case 1 (A) and Case 3 (B); higher magnification showing cytologic features of MALT lymphoma (C) (hematoxylin & eosin, original magnification: A, × 50; B, × 100; C, × 400)

Fig. 2

Photomicrographs showing positive CD20 and kappa staining of the conjunctival MALT lymphoma of Case 1. Note positive CD4 T-cells and lack of lambda expression in the tumor (avidin-biotin-complex immuno-peroxidase with counter-staining of methyl green, original magnification, x 200, insert, x 400

Fig. 3

PCR amplification showing IgH gene rearrangements of CDR3 region with different primer sets in the 5 cases of conjunctival MALT lymphoma (lane 1-5, Case 1-5; lane 6, negative control; lane 7, positive control).

Fig. 4

PCR and Southern blot showing detection of both H. pylori urease B and vacA m2 genes in the MALT lymphoma of Case 1-4 (lane 1-4, Case 1-4; lane 5, Case 5; lane 6, negative control; lane 7, positive control).

Fig. 5

PCR showing absent H. pylori genes in the conjunctival resident cells, orbital MALT lymphoma, conjunctivitis, and conjunctival HTLV-1/ATL (lane 1, conjunctival MALT lymphoma cells of Case 1; lane 2, conjunctival non-lymphoma cells of Case 1; lane 3, conjunctival MALT lymphoma cells of Case 2; lane 4, inflammatory cells from conjunctivitis; lane 5, conjunctival HTLV-1/ATL cells; lane 6. orbital MALT lymphoma cells; lane 7, negative control; lane 8, positive control).