Diagnóstico del linfoma de la zona marginal (linfoma MALT) gástrico temprano, en biopsias endoscópicas. Informe de un caso que ilustra la utilidad de la inmunohistoquímica y el análisis molecular

MALT lymphomas are a subtype of low grade lymphomas that represent 7-8% of all B-cell lymphomas originated in extranodal sites. Nearly 50% of the cases present as primary gastric lymphomas. They arise from the acquired MALT developed dur- r ing the course of H. pylori chronic infection. Microscopically, the presence of lymphoid follicles with follicular colonization, marginal zone (`centrocytoid¿) cells and lymphoepithelial lesions is char- r acteristic. Histopathological diagnosis may result difficult in superficial endoscopic biopsies showing atypical lymphoid infiltrates. Using Wotherspoon criteria along with molecular analyses is useful in borderline lesions. We present the case of a 62 years old female with chronic gastritis. A small endoscopic biopsy was performed and the presence of a heterogeneous lymphoid infiltrate in the lamina propia was observed. Immunohistochemical profile showed focal co expression of CD20 and CD43 and kappa light chain restriction. The diag- g nosis of an atypical lymphoid infiltrate highly suspicious of MALT lymphoma was established. PCR molecular analysis corroborated the monoclonal pattern of the lymphoid cells and the diagnosis of lymphoma. Immunohistochemical and molecular analyses in cases of lymphoid infiltrates suspicious of malignancy (Wotherspoon 3 and 4) will aid in the adequate diagnosis between chronic gastritis and MALT lymphoma, which is crucial for prognosis, treatment and patient¿s outcome.©Revista de Gastroenterología de México