Analysis of chromosome 12p deletion in plasma cell dyscrasias.

The prognostic relevance of 12p deletion is controversial in multiple myeloma (MM) and the status of 12p deletion is unknown in other plasma cell disorders. We investigated 12p deletion in 88 patients with MM, 19 patients with monoclonal gammopathy of undetermined significance (MGUS), and 17 patients with plasma cell leukemia (PCL). Cytoplasmic immunoglobulin light chain immunofluorescence with simultaneous FISH analysis (cIg-FISH) detected hemizygous 12p deletion in 8% of MM and 24% of PCL, respectively, but in none of the MGUS cases (p=0.0366). 12p deletions were found in 5 of 7 (71%) MM patients at diagnosis with stage III disease (Durie-Salmon), 2 of 7 (28%) with stage I or II. Of 11 cases with 12p deletions, 6 (55%) had coexistence of p53 deletions, including 3 of 7 (42%) MM, and 3 of 4 (75%) PCL cases. There were no significant differences in progression free or overall survivals in MM patients with or without 12p deletions. Our results do not support the use of 12p deletion as a prognostic marker in MM, rather, it tends to occur in advanced disease, may represent a secondary change associated with the disease progression.