Effect of splenectomy on teardrop-shaped erythrocytes in agnogenic myeloid metaplasia

Teardrop-shaped erythrocytes (TD) are frequently observed in the peripheral blood of patients with agnogenic myeloid metaplasia (AMM). These deformed cells may result from the myelofibrosis or the extramedullary hematopoiesis in the spleen. To determine the influence of the spleen on TD formation, we reviewed the presplenectomy (pre-S) and postsplenectomy (post-S) peripheral blood smears from 13 patients with AMM. The splenectomy was performed for a variety of reasons, including symptomatic hypersplenism or splenomegaly. The average number of TDs per 1,000 RBCs in the pre-S smears was 42 (range, 15 to 112 TDs), compared with 11 TDs in the post-S smears (range, 6 to 20 TDs)(P = less than .001). Only one of the 13 patients failed to exhibit this decrease in TDs post-S. There was no definite correlation between the number of TDs and the weight of the spleen removed at surgery, the interval since surgery, or age and sex of the patient. Based on this fourfold decrease in the number of TDs post-S, we conclude that the spleen in AMM play an important role in TD formation.