*5.2.3. High-grade B-cell-lymphoma*


### *5.2.4. Others*

• Gastroblastoma: benigne bi-phasic tumour in children. Epithelial component can be posi-

• Plexiform fibromyxoma: SMA, CD10 (very rare; multinodular, myxoid stroma, paucicellular, no atypia, prominent capillary network, just few mitosis, typically in wall of

The great majority of gastric malignant lymphoma in Western countries belongs to the mucosa-associated lymphoid tissue (MALT) subtype. About 70–80% of MALT-lymphomas are associated with a chronic helicobacter pylori (Hp) infection. The Hp-infection is one of the main drivers of this type of lymphoma; eradication of Hp is the first choice of treatment and induces a regression of the MALT-lymphoma in about 75% of cases. Hp-negative MALTlymphoma can be associated with some other infections (like Hepatitis C) or are related to immunosuppression (due to AIDS or post-transplant) or some autoimmune diseases. Prognosis is mainly related to stage (Ann Arbor staging). Gastric MALT lymphoma occurs frequently multifocal. It is noteworthy that some gastric MALT lymphoma can affect other

Endoscopically, (MALT)-lymphoma imitates carcinoma (including mucosa-ulceration) and is usually located in distal parts of the stomach. Sometimes non-characteristic gastritis-like or

Histologically, MALT-lymphoma shows the characteristics of other marginal zone lymphomas like dense infiltrations of small to intermediate-sized more or less monomorphic lymphoid cells with clear cytoplasm. Some tumours show a striking plasmacytoid-like differentiation. Lympho-epithelial lesions (destruction of epithelial components of the mucosa) are highly characteristic for this type of lymphoma. Scattered blasts are typical [34, 35].

Immunohistochemically, MALT-lymphomas are positive for CD20 and half each for CD43.

Hp-eradication is the first choice of treatment (independent of Hp status at the surrounding mucosa). But tumours with nuclear BCL10 expression and positive translocation t (11;18) (q21;q21)) fail to response to Hp-eradication. This subtype is associated with a low risk of

All other B- and T-cell-lymphomas and some other rare differential diagnosis can primary occur in the stomach, but are frequently an expression of a secondary infiltration (compare

tive for CD117, mesenchymal component CD10 positive

*5.2.1. Marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT)*

MALT-bearing organs like gut, salivary glands and bronchial [2, 33].

• Granularcelltumour: S100

**5.2. Malignant lymphoma**

nodular appearance dominates.

*5.2.1.1. Clinical significance*

Sections 5.2.2–5.2.4) [39].

Negative for CD10, cyclin D1, CD5, CD23.

progression into an aggressive B-cell-lymphoma [36–38].

stomach)

282 Gastric Cancer

