**Abstract**

Marginal zone lymphoma (LMZ) accounts for 5–15% of all NHL in Europe. This option includes splenic (0.7%), nodal (2.4%) and extranodal (MALT-Mucosa-Associated Limphoid-Tissue) LMZ −5%. Extranodal variants of MALT lymphomas can occur in any organ due to chronic antigenic stimulation. The most frequent localization associated with *Helicobacter pylori* (*Hp*) infection is the stomach - 30%. The gastrobiopsy material of 115 patients with lymphoid cell infiltrates in the gastric mucosa was studied, a complex of morphological diagnostic criteria for MALT gastric lymphoma for gastrobiopsy was developed based on a combination of histological and immunohistochemical characteristics of tumor cells, the nature of their growth. It is known that the mandatory initial therapy for local stages of *Hp*positive MALT lymphoma of the stomach is the eradication of *Hp*. 68 patients with stages I – II of gastric MALT lymphomas were observed. Anti *Hp* therapy resulted in 87.8% of complete remissions, with a median duration of 51 months. The median time to the onset of *Hp*-eradication was 3 months, and the median time to the implementation of the antitumor process was 5.5 months. With a median followup of 58 months, the median overall and relapse-free survival was not achieved: 10-year OS - 100%, 10-year RFS - 92. 3%.

**Keywords:** MALT lymphoma, stomach, gastrobiopsy, morphology, immunohistochemistry, anti-*Helicobacter pylori* therapy

### **1. Introduction**

Mucosa-associated lymphoid tissue (MALT) lymphoma is an indolent extranodal marginal zone B-cell lymphoma, originating in acquired MALT that is induced in mucosal barriers as part of a normal adaptive immune response to a chronic immunoinflammatory stimulus, most notably chronic infection by *Hp* [1].

MALT lymphomas can show a wide morphologic spectrum. MALT gastric lymphoma is characterized by mature cellular elements, the presence of lymphoid follicles and lymphoepithelial lesions (LELs) [2]. Histological diagnosis of MALT lymphoma of the stomach is rather difficult and is made basing on a combination

of morphological features because none of them is exclusively pathognomic for this lymphoma type [3, 4]. Immunohistochemical analysis is much importance in the diagnosis of MALT-lymphoma, especially in controversial cases [5–7].

In recent years, the principles of MALT lymphoma treatment have been defined. According to the recommendations of the European Society of Medical Oncologists (ESMO), at the first stage of treatment of patients with *Hp* + MALT gastric lymphoma, regardless of the stage, it is recommended to prescribe anti-*Hp* eradication therapy. However, there is an addition in the guidelines of the general cancer network. According to the addition Eradication Antibiotic Therapy is preferable for patients with stages I and II1 according to Lugano, in the absence of translocation t(11; 18), which is found in 15-40% of patients with gastric MALT lymphoma and is a predictor of refractoriness to antibiotic therapy. These patients with translocation t(11, 18) should in any case receive additional treatment. Alternatively, rituximab alone or radiation therapy can be used.

As an antibacterial anti-*Hp* therapy, a 3-component regimen is usually used: a proton pump inhibitor with clarithromycin, in combination with amoxicillin or metronidazole for 10-14 days. The effect should be confirmed morphologically 6 weeks after eradication therapy and at least 2 weeks after discontinuation of the proton pump inhibitor.

Patients with a widespread tumor process - more than stage IIe require a systematic approach in the presence of indications for therapy.
