Polycythemia rubra vera versus secondary polycythemias. A clinicopathological evaluation of distinctive features in 199 patients

To determine parameters of distinctive value in polycythemia rubra vera (PV ) versus secondary polycythemias (SP), a clinicopathological study was perf ormed on 199 patients. These presented with a borderline to marked elevatio n of the hemoglobin level (> 18 g/dl in men and > 16 g/dl in women). Evalua tions of clinical features and bone marrow histopathology were carried out independently. According to the results derived from laboratory data and re presentative pretreatment trephine biopsies, three groups of -patients emer ged: group I presenting with the concordant clinical and morphological find ings of early to manifest PV (136 patients), group II consisting of 55 pati ents with the congruent signs and symptoms of SP mostly caused by various c hronic bronchopulmonal disorders, and finally eight patients (group III) wi th divergent findings. Between group I and II patients (PV versus SP), a nu mber of clinical parameters proved to be significantly different. With the exception, of the red cell mass, platelet count, leukocyte alkaline phospha tase, LDH, spleen size, and the erythropoietin level had a significantly di scriminating impact. Morphological features of distinctive value consisted of a set of specific lesions. Contrasting SP with an only borderline to sli ght increase in cellularity associated with a moderate enlargement of the e rythroblastic islets, PV was always characterized by a significant increase in hematopoiesis, revealing a trilinear proliferation (panmyelosis). Megak aryopoiesis was strikingly different in PV as compared to SP by displaying clustering and a pleomorphous appearance, i.e., very small and giant megaka ryocytes with staghorn-like nuclei were neighboring each other. Moreover, c onspicuous alterations of the interstitial compartment were recognizable in SP. These consisted of deposits of cell debris in histiocytic reticular ce lls, iron-laden macrophages, and a plasmacytosis, implying an inflammatory reaction. These changes were only very rarely observed in PV, as opposed to a minimal to slight increase in reticulin fibers in about 12% of patients. In conclusion, a more elaborate evaluation of bone marrow features resulte d in a set of diagnostic criteria with discriminating capacity that should be considered in prospective clinical trials.