Acute panmyelosis with
myelofibrosis (APMF) is an ill-defined disorder that may either evolve as a clonal hematopoietic condition or as a sequel of toxic exposure to the bone marrow (BM). Therefore, controversy and discussion continues as to whether APMF may be considered as a hyperfibrotic (de novo)
myelodysplastic syndrome (MDS), as
acute myeloid leukemia (AML) or as a severe toxic
myelopathy with accompanying
myelofibrosis. In this context scant knowledge exists about BM findings, but especially evolution of this disorder according to sequential examinations. Clinically patients present with
pancytopenia, a very few blasts in the peripheral blood and no or little
splenomegaly. Initially BM histopathology is characterized by different degrees of
reticulin-
collagen fibrosis and wide ranges of cellularity with a prominent left-shifted and often macrocytic erythropoiesis associated with a reduction and maturation defects of the neutrophil series. Most conspicuous are abnormalities of the megakaryocytes including loose clustering, dislocation towards the endosteal border and appearance of atypical microforms with compact nuclei. Moreover, besides
myelofibrosis in a number of patients the interstitial compartment displays a remarkable inflammatory reaction with lymphoid nodules, abundant
iron-laden macrophages, perivascular plasmacytosis and increase in microvessels. Repeatedly performed BM biopsies reveal an accumulation of dispersed or clustered CD34+ and
lysozyme-expressing blasts in keeping with the insidious transformation into acute
leukemia. Prognosis is unfavorable with a median survival of less than 1 year. In conclusion, APMF has to be regarded as a condition that shows considerable overlappings with primary hyperfibrotic MDS, AML and toxic
myelopathy (secondary MDS) with accompanying
myelofibrosis and therefore can not be considered as a definite clinical entity.