[A clinical analysis of 25 cases of multiple myeloma complicated by extramedullary plasmacytomas]

To investigate the clinical features of multiple myeloma (MM) complicated by extramedullary plasmacytomas (EM).

Twenty five patients were enrolled into the study. The proportion male to female was 15:10 and the median age 55.2 years. The distribution of different isotypes was IgA ten, IgG nine and light chain lambda five. The sites of complicating plasmacytoma included muscle, bone, skin, rectum, and testicles. The most common site was muscle.

Patients with complicated extramedullary plasmacytomas at the time of diagnosis received traditional treatment, including vincristine adriamycin, dexamethasone, medphalan, prednisone, thalidomide and bortezomib. Rates of overall response (ORR) were 80%. Plasmacytomas occurring after the diagnosis of MM received cisplatin, etoposide, cyclophosphamide, prednisone, or bortezomib ORR were 66.7%, 50.0%.

These results lend support to the efficacy of bortezomib in the treatment of plasmacytoma. MM cases with unconventional disease recurrence are likely to be seen due to sub-clinical seeding of tumour cells suggestive of the presence of an EM clone of plasma cells with a high degree of chemoresistance. Available data in the literature concerning the optimal therapy for patients with EM relapse were reviewed.