<aside> 💡 CD19+, CD20+, CD79a+, IgM+, CD5-, CD10-, CD23-, cyclin D1-, BCL2-, BCL6-, CD138+/- t(11;18)(q21;q21) → resistant to HP eradication

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• MZLs account for between 5% and 7% of all NHL and include nodal based disease, extranodal lymphoma of MALToma, and SMZL.
• Clinically, they behave indolently and have a prolonged course.
• Slight female predominance.
• The term marginal zone refers to a histologic compartment located at the periphery of lymphoid follicles immediately outside their mantle zone. The marginal zone is especially evident in the spleen, although identical areas have been observed in other lymphoid structures, including mesenteric lymph nodes and mucosa-associated lymphoid tissue (MALT).

Extranodal MALT Lymphoma (ENMZL)

• ENMZL is the most frequent of the MZL subtypes, accounting for approximately 8% of all NHL.
• Ｍedian age of presentation is around 60, with a wide range spanning from the third to the ninth decades.
• Frequently presents at a localized stage (≈40% stage I, and ≈30% stage II), and the risk for systemic dissemination is low (albeit variable depending on primary location).
• B symptoms are uncommon (≈15% of cases).
• Typically positive for IgM or, less commonly, IgA or IgG, with light chain restriction. IgD expression is usually negative or very weak. These immunoglobulins may be secreted, especially when there is significant plasmacytic differentiation (especially in association with cutaneous, thyroid, and intestinal), and can give rise to a monoclonal band in the serum protein electrophoresis.
  • ENMZL and may pose differential diagnosis problems with lymphoplasmacytic lymphoma. These plasmacytoid cells often contain periodic acid–Schiff (PAS)–positive inclusions, known as Dutcher or Russell bodies, depending on whether they are located over the nucleus or in the cytoplasm, respectively.
• The most commonly affected primary site is the mucosa of gastrointestinal tract, in particular the stomach (approximately 44% of all ENMZL cases) followed by the small intestine (≈7%).
• Ocular structures are also frequently involved (≈12%), namely, the orbit (≈40% of all ocular adnexal ENMZL), the conjunctiva (35%–40%), the lacrimal glands (10%–15%), and the eyelids (≈10%).
• Other commonly affected sites include the bronchial mucosa (≈11% of all ENMZL cases), the skin (≈9%), the salivary glands (≈6%), and the thyroid gland (≈6%).
• More rarely reported sites are Waldeyer pharyngeal lymphoid ring, breast, liver, pancreas, urogenital tract, and central nervous system.
• There are lymphoid infiltrates invading and destroying glandular structures, with eosinophilic degeneration of epithelial cells (so-called lymphoepithelioid lesions).
• Prognosis of limited stage ENMZL is excellent, as mentioned in each of the treatment subsections.
• Even for advanced disease, the expected lymphoma-specific survival at 5 years is close to 90%, with some series showing survivals similar to those of early disease.
  • A recent retrospective analysis of SEER data lists the best 5-year overall survivals for cutaneous (88%), ocular (83%) and thyroid (85%) forms, and worst for genitourinary (76%), intestinal (69%), and central nervous system (71%).

MALToma of the Stomach: Model for Lymphomagenesis