Table 4.

WHO Diagnostic criteria for primary myelofibrosis (requires all 3 major criteria and more than 2 minor criteria)⁽³²⁾

I. Major criteria
	a. Megakaryocyte proliferation, including small-to-large megakaryocytes, with aberrant nuclear/cytoplasmic ratio and hyperchromatic and irregularly folded nuclei and dense clustering accompanied by either reticulin and/or fcollagen ibrosis or , in the absence of reticulin fibrosis (i.e. prefibrotic), megakaryocyte changes must be accompanied by increased marrow cellularity, granulocytic proliferation.
	b. Not meeting WHO criteria for chronic myelogenous leukemia, polycythemia vera, myelodysplastic syndromes or other myeloid neoplasms
	c. Demonstration of JAK2V617F or other clonal marker or, in the absence of a clonal marker, no evidence of reactive marrow fibrosis (infection, auto immune disorder, hairy cell leukemia, lymphoid neoplasm, metastatic malignancies and toxic myelopathies)
II. Minor criteria
	a. Leukoerythroblastosis
	b. Increased serum lactate dehydrogenase
	c. Anemia
	d. Palpable splenomegaly