Ultrastructure of myeloma cells producing parathyroid hormone-related peptide

We examined the ultrastructure of myeloma cells producing parathyroid hormone-related peptide. The nucleus was mature and the cytoplasm was well-developed, being classified into the mature type with slight nucleo-cytoplasmic asynchrony. Although various nuclear and cytoplasmic abnormalities commonly observed in myeloma cells were recognized, a multilamellar body-like structure which has not been reported previously in myeloma cells was characteristically observed. Numerous nuclear and cytoplasmic abnormalities observed in the myeloma cells of this case were considered to have resulted from increased and aberrant proliferation of myeloma cells. We reported previously that the immature nucleus and various nuclear and cytoplasmic abnormalities are related to poor prognosis. Thus, the ultrastructural findings of myeloma cells in this case is not inconsistent with the short survival time.