Myeloid metaplasia in aspirates from enlarged spleens: a clue in the absence of peripheral blood findings characteristic of myelofibrosis.

OBJECTIVE: To assess the significance of finding myeloid metaplasia in splenic aspirates from patients presenting with mild to moderate firm splenomegaly, in the absence of characteristic peripheral blood findings, in diagnosing idiopathic myelofibrosis. STUDY DESIGN: Archival records pertaining to 14 patients diagnosed as having myeloid metaplasia on splenic aspirates performed between September 2000 and April 2004 were analyzed. RESULTS: The relevant findings in these 9 women and 5 men were: splenic enlargement 17-21 cm with homogeneous echotexture on ultrasonography, hemoglobin 4-10 g/dL, variable pattern of anemia, total leukocyte count 6,300-28,800/ mm3 with neutrophilia and a few late myeloid precursors on the differential count, normal platelet counts, dry bone marrow tap in 10 patients and cellular marrow aspirate with prominence of megakaryocytes dispersed in a maturing cell population of myeloid and erythroid series in 4 patients. Splenic aspirates yielded foci of trilineage hematopoiesis suggestive of myeloid metaplasia, possibly due to myelofibrosis of idiopathic type, as confirmed on trephine biopsy in all cases. CONCLUSION: Splenic aspirates may be a useful tool for detecting myeloid metaplasia suggesting myelofibrosis when peripheral blood findings are not yet characteristic of the same. The procedure was not associated with any complications.