To determine possible differentiating characteristics of CCND1/IGH FISH complexity between MCL and PCM, we analyzed the CCND1/IGH FISH patterns for 326 cases of MCL with CCND1/IGH (275 FFPE specimens; 51 BM specimens) and 279 cases of PCN with CCND1/IGH (56 FFPE specimens; 223 BM specimens). The gene discussed is CCND1; the disease is mantle cell lymphoma.