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

Non-Hodgkin's lymphomas represent the most common ocular adnexa neoplasm [1]. Approximately accounting 5-15% of all extranodal lymphomas localize at ocular adnexa, including the conjunctiva, the lachrymal gland, the orbital fat, the eyelid and the lachrymal sac [2]. In Western countries Marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT)-type accounts 50-78% of all ocular lymphomas, while in Japan and Korea the relative frequence is much higher [3]. It has been recorded that Ocular Adnexal MALT Lymphoma (OAML) increases by more than 6% for year. These data are only partially explained by the development of recent new lymphoma classification and improvement of diagnostic approaches [4].MALT-lymphomas represent a wide range of extranodal lymphomas that often recognize environmental factors driving to specific genes deregulation. Interestingly, environmental factors are specifically related to sites of acquired MALT development and furthermore the deregulated genes, even if involved in the NF-kB pathway, share different distribution in extranodal sites [5,6]. Among environmental factors, some bacterial infections have been found associated to MALT lymphomas of specific anatomic districts, such as H. pylori in gastric MALT lymphoma, C. Jejuni in intestinal MALT lymphoma and Borrelia Burgdoferi in cutaneous B cell lymphoma [6-10]. Recently Chlamydia psittaci (Cp) has been identified in OAML [11-25]. Chromosomal aberrations involving mainly MALT1 and bcl10 genes with consequent deregulation of their gene expression are commonly observed in MALT lymphomas, but with different distribution dependently from specific anatomic regions, being t(11;18) more frequent in gastric MALT lymphomas and t (14;18) in extragastric MALT lymphoma [26-29]. Moreover environmental and biological features show a relevant variability also related to geographic area. In fact Cp frequence in OAML has been described with difference frequence all over the world (Table 1) [11-25]