Maldonado, Jorge E.

Abstract Small circulating megakaryocytes were identified in four patients with chronic myeloproliferative disorders, and their morphologic features by light and electron microscopy are described. The morphologic and cytogenetic studies suggest that at least some of these cells are truly mononuclear. The circulating megakaryocytes were associated with the presence of dysplastic platelets. Both findings are thought to represent involvement of the megakaryocytic-platelet line, probably as an expression of stem cell disease.

Abstract A 58-yr-old woman is described in whom light and electron microscopic studies of bone marrow revealed the typical features of type I dyserythropoietic anemia. This form of anemia may be first diagnosed late in life, and caution should be exerted to avoid its confusion with preleukemia or erythroleukemia.

Abstract A light and electron microscopic study was made of the circulating platelets from five patients with variants of the chronic myeloproliferative diseases (agnogenic myeloid metaplasia, chronic granulocytic leukemia, and "megakaryocytic leukemia"). Morphologic abnormalities were found in at least some of the platelets in all of the patients. Presence of giant forms, paucity or absence of granulation, disorganization and scarcity of the microtubules, and haphazard distribution and hypertrophy of the dense tubular and open canalicular systems constituted the main abnormalities. Additionally, there were features of platelet immaturity, including abundant rough endoplasmic reticulum and ribosomes and presence of Golgi profiles, centrioles, and nuclear remnants. The relationship, if any, of these morphologic abnormalities to the hemostatic defects in myeloproliferative diseases remains to be elucidated.

Abstract A patient with symptomatic primary cryoglobulinemia was followed for 9 yr and was found at autopsy to have generalized amyloidosis. There was a monoclonal serum protein spike of IgG kappa type that was cryoglobulin. The cryoglobulin was further characterized as IgG2 kappa Gm (n-). This case constitutes, to our knowledge, the first example of amyloidosis associated with monoclonal IgG cryoglobulinemia, with characterization of the monoclonal serum cryoglobulin, and also the first reported case of successful symptomatic treatment of cryoglobulinemia by plasmapheresis.

Abstract Bone marrow studies of multiple myeloma revealed, in some cases, a conspicuous proliferation of "lymphoid" cells, virtually indistinguishable by light microscopy from those seen in lympho-proliferative disorders. Electron microscopy demonstrated a variety of cells ranging from typical lymphocytes to cells with plasmocytoid features. Between these two types of elements there were cells with intermediate characteristics. In addition, in several cases of myeloma the presence of fixed reticuloendothelial cells and "reticular" plasma cells (or reticulum cells with plasmocytic features) was frequently noted. The presence of reticulum cells and lymphocytes and of cells apparently "intermediate" between these cellular elements and plasma cells, as judged from electron microscopic observations, is suggestive morphologic evidence of a phenomenon of cell transformation and evidence of a mixed cell proliferation in certain cases of multiple myeloma.