Trisomy 3 in gastric lymphomas of extranodal marginal zone B-cell (mucosa-associated lymphoid tissue) origin demonstrated by FISH in intact paraffin tissue sections

Some reports have indicated that trisomy 3 represents a characteristic chro mosomal abnormality found in lymphomas arising in mucosa-associated lymphoi d tissues (MALT)/extranodal marginal zone B-cells (MZBC). Traditional cytog enetic analysis of metaphase preparations is cumbersome and not always poss ible, especially in those situations in which the diagnosis in not suspecte d before a biopsy. Our aim is to use a relatively simple method to evaluate trisomy 3 in paraffin-embedded, formalin-fixed tissue, using fluorescence in situ hybridization (FISH) on intact tissue sections. Formalin-fixed, par affin-embedded archival tissues from 30 cases (27 lymphoma and 3 chronic ga stritis cases) were hybridized with a chromosome 3 specific alpha-satellite probe (ONCOR, Gaithersburg, MD). Three of four cases of gastric MZBC/MALT lymphoma revealed trisomy 3. Ten cases of lymphoma of possible or probable MZBC origin were examined, and four revealed trisomy 3. Five of 13 non-MZBC lymphomas revealed trisomy 3. None of the chronic gastritis cases nor norm al tonsil cases revealed trisomy 3. Our results, using a different methodol ogical approach, confirm the findings of others that trisomy 3 is an abnorm ality found in a significant proportion of lymphomas of MZBC origin. Our ap proach also makes possible interphase cytogenetic analysis (by FISH) of rou tinely processed formalin-fixed, paraffin-embedded tissues, without the nee d to disaggregate cells. It thus may facilitate genetic analysis on specime ns previously deemed unsuitable for such analysis, particularly when tissue quantity is limited. Copyright (C) 1999 by W.B. Saunders Company.