Background: Helicobacter pylori positive gastric mucosa-associated lymphoid tissue lymphoma (MALT lymphoma) has been extensively studied but there are only limited data on the typical features of larger “wild-type” MALT lymphoma collectives, and particularly prognostic factors for non-gastric or eradication refractory patients including assessment of predictive markers for different treatment strategies need to be further investigated. Aim: The aim of this thesis was to evaluate systematically clinico-pathological and treatment-related features of MALT lymphoma patients and investigate potential prognostic markers based on a newly generated dataset of all patients treated at the Medical University Vienna, Department of Medicine I, Clinical Division of Oncology 19992015. Results: With a total of 327 patients documented and analyzed within this thesis, this is one of the largest collectives reported to date (median follow-up time 55.2 months). Results are presented in form of a cumulative thesis including four publications arising from these data: 1.) Ocular adnexal MALT lymphoma: An analysis of 60 patients with ocular adnexal lymphoma confirms the excellent prognosis of this distinct subgroup irrespective of the initial treatment approach. In contrast to recent data evaluating particularly radiotherapy as first line therapy, we suggest that also systemic or antibiotic treatment is reasonable. 2.) Gender-specific aspects: Acknowledgement of gender-related aspects should be standard in clinical research 2017. However, there are no data addressing this issue for MALT lymphoma. We present the first systematic analysis on gender-specific aspects in terms of clinico-pathological features, treatment and outcome in a large collective of MALT lymphoma patients (n = 327). 3.) Potential predictive markers: CRBN and MUM1 have both been suggested as potential predictive markers for response to IMiDs. We have assessed the association of immunohistochemical expression of CRBN/ MUM1 and response to lenalidomide in 46 MALT lymphoma patients. In contrast to prior results, there was no clear relation between CRBN/ MUM1 expression and outcome. Our data will possibly avoid over-testing of these two respective markers. Further investigations are warranted. 4.) Prognostic score for MALT lymphoma: Data documented within this thesis contributed to the development of a new prognostic tool for the disease of MALT lymphoma. Conclusion: To conclude, the data assessed within this thesis contribute to further characterization of MALT lymphoma in terms of clinico-pathological features, prognostic factors and novel treatment approaches and offer a more concise knowledge on sub-populations and long-term outcome following different therapeutic strategies. The documented collective appears to be well representative for this entity and will most potentially allow to generate further hypotheses and support planning of future projects.