[Contemporaneous presentation of plasma cell leukemia and multiple myeloma. Description of a clinical case with a biclonal component].

A case of simultaneous evidence of plasma cell leukaemia and multiple myeloma is reported. Plasma cell leukaemia doesn't represent an evolution of multiple myeloma, but a primitive disease, because the two forms of plasma cell dyscrasia arose from two different neoplastic plasma cell populations. In fact, leukaemic plasma cell produced IgA and were PAS-positive, while myelomatous plasma cells produced IgG and were PAS-negative. From this case, some hypothesis on simultaneous development of the two types of plasma cell neoplasias are discussed.