Features of solitary plasmacytoma:
(1) solitary lesion of bone or soft tissue
(2) lesion composed of plasma cells demonstrated on biopsy
(3) normal bone marrow biopsy (collected away from solitary lesion) with no evidence of clonal plasma cells
(4) normal skeletal survey
(5) normal MRI of spine and pelvis
(6) absence of end-organ damage (anemia, hypercalcemia, renal failure, additional lytic bone lesions) that can be attributed to a plasma cell proliferative disorder
An essential diagnostic step is the exclusion of any plasma cells lesions that may be occult.
Sites where a solitary plasmacytoma have been described:
(1) bone
(2) nasal cavity or sinuses
(3) nasopharynx
(4) larynx
(5) gastrointestinal tract
(6) central nervous system (CNS)
(7) urinary bladder
(8) thyroid
(9) breast
(10) testes
(11) parotid gland
(12) lymph nodes
Factors associated with progression to multiple myeloma:
(1) high microvessel density
(2) baseline serum monoclonal protein > 1 g/dL
(3) persistence of serum and/or monoclonal protein after radiation therapy for >= 1 year
