Chlamydia psittaci in ocular adnexa MALT lymphoma: a possible role in lymphomagenesis and a different geographical distribution

Abstract

Ocular adnexa MALT-lymphomas represent approximatively 5-15% of all extranodal lymphomas. Almost 75% of OAMLs are localized in orbital fat, while 25% of cases involves conjunctive. MALT-lymphomas often recognize specific environmental factors responsible of lymphoma development and progression. In particular as Helicobacter pylori in gastric MALT lymphomas, other bacterial infections have been recognized related to MALT lymphomas in specific site. Recently Chlamydia psittaci has been identified in Ocular Adnexa MALT lymphomas, with variable frequence dependently from geographic areas. Thus bacterial infection is responsible of clonal selection on induced MALT with subsequent lymphoma development. Moreover Chlamydia psittaci could promote chromosomal aberration either through genetic instability as a consequence of induced proliferation and probably through DNA oxidative damage. The most common translocation described in MALT lymphomas affects NF-kB pathway with a substantial antiapoptotic effect. Several therapeutic approaches are now available, but the use of antibiotic-therapy in specific cases, although with conflicting results, could improve the treatment of ocular adnexa MALT lymphomas. In this review we analyse the most relevant features of Ocular adnexa MALT lymphomas, underlining specific biological characteristics mainly related to the potential role of Chlamydia psittaci in lymphomagenesis.

Figure 1

(a) OAML infiltration of the lacrimal gland, showing squamous metaplasia (H&E) (10×); (b) prevalence of plasmocytoid cells in OAML (H&E) (40×); (c) prevalence of centrocytic cells around a residual germinal center in OAML (H&E) (40×); (d) prevalence of monocytoid cells in OAML (H&E) (40×).

Figure 2

CD20 and Bcl10 immunohistochemical expression; (a) Diffuse CD20 staining (60×); (2) High cytoplasmic Bcl10 expression (40×); (3) High nuclear Bcl10 expression (40×); (d) Negativity for Bcl10 (40×).

Figure 3

Schematic representation of lymphomagenesis potentially induced by Chlamydia psittaci (Cp) in acquired MALT with follicular germinal center (A) with consequent clonal selection, characterized by clonal expansion of marginal zone lymphoid cells invading (B) and then replacing germinal center (C).

Figure 4

Schematic representation of OAML biological progression from Cp-clonal selection (A) to lymphoma with chromosomal aberration (B) and finally to histological progression to Diffuse Large B cell Lymphomas (C). Antibiotic therapy could be efficacy only in the phase of CP antigen dependent growth.

Figure 5

FISH; (a) T (11;18) (100×). Yellow fusion signals (arrow) of API2 (green) and MALT1 (red) translocation; (b) T (14;18) (100×). Yellow fusion signals (arrow) of IGH (green) and MALT1 (red); (c) T (1;14). (60×) Dual color break Apart rearrangement BCL10 probe. Following the translocation, there is a split signal.