Primary mucosa-associated lymphoid tissue lymphoma of the gallbladder: report of a case harboring API2/MALT1 gene fusion..     ///    "Interphase fluorescence in situ hybridization analysis on paraffin sections, using a fusion probe for API2/MALT1, demonstrated 2 fusion signals in most nuclei, bringing the first documentation of a t(11;18)(q21;q21) in this exceptional primary disease location.. "