[Non-secretory myeloma syndrome]

Non secretory myeloma is a rare and unusual form of myeloma, characterized by the absence of monoclonal component in serum and urine. This peculiarity is usually believed to be caused by the incapacity of neoplastic plasmacells to synthesize or secrete M-component, but it is probably due to several pathogenetic mechanisms which are different from case to case. The diagnosis can be delayed by the non specific clinical pattern, especially in those cases where skeletal radiological studies do not reveal lytic lesions. The authors report two recently diagnosed cases of non secretory myeloma, underlying the main clinical and laboratory findings which led to the diagnosis of this singular syndrome. The diagnostic suspicion is often based, beside the clinical pattern at the onset, on the absence of serum and urinary monoclonal component, on the increase of PCR, of beta 2 microglobulin and on low levels of serum immunoglobulins. CT scans, MRI and Tc 99 MIBI bone marrow radionuclide studies are also useful in evaluating the therapeutic response which cannot be based on quantitative variations of the M-component. The clinical suspicion is confirmed by the bone marrow aspiration and trephine biopsy, showing a typical infiltration by plasmacells at various degree of maturation.