We studied the presence of tumour cells in PB in gastric lymphoma patients harbouring or lacking t(11;18)(q21;q21), by real-time immunoglobulin (Ig)H allele-specific oligonucleotide-polymerase chain reaction (ASO-PCR) and API2-MALT1 PCR.     ///    Monitoring gastric lymphoma in peripheral blood by quantitative IgH allele-specific oligonucleotide real-time PCR and API2-MALT1 PCR.. 