Solitary plasmacytoma

Can be subdivided into

• isolated plasmacytoma of the bone
• extramedullary plasmacytoma (1,2)

Extramedullary plasmacytoma

• is a focal neoplasm of plasma cells that may occur outside the bone marrow
• may occur in any organ including the gastrointestinal tract, CNS, urinary bladder, thyroid, breast but the most frequent site is the upper respiratory tract, for example nasal cavity and sinuses, nasopharynx and larynx
• the plasma cells are identical to those of multiple myeloma
• negative findings on skeletal x-rays and bone marrow biopsy (2)
• intensive radiation therapy eradicates the tumour in virtually all patients
• are less likely to progress to multiple myeloma.

Isolated plasmacytoma of the bone

• solitary plasmacytoma of bone is regarded to be the earliest stage of multiple myeloma - 50 to 60% progress to multiple myeloma within 5 years, 15% remain solitary, 12% develop local recurrence, and 15% develop new distant lesions.
• the following criteria are used for the diagnosis of solitary plasmacytoma of the bone (all three are required)
  • biopsy-proven plasmacytoma of bone in a single site only. X-rays and magnetic resonance imaging and/or FDG PET imaging (if performed) must be negative outside the primary site. The primary lesion may be associated with a low serum and/or urine M-component
  • the bone marrow contains no monoclonal plasma cells
  • no other myeloma-related organ dysfunction (1)

Reference:

• (1) National Cancer Institute 2011. Plasma Cell Neoplasms (Including Multiple Myeloma) Treatment
• (2) Reed V et al. Solitary plasmacytomas: Outcome and prognostic factors after definitive radiation therapy. Cancer. 2011;doi: 10.1002/cncr.26031
• (3) Palumbo A et al. International Myeloma Working Group guidelines for the management of multiple myeloma patients ineligible for standard high-dose chemotherapy with autologous stem cell transplantation. Leukemia. 2009;23(10):1716-30.