Intrasinusoidal proerythroblast infiltration in therapy related myeloid neoplasm.

A 67-year-old patient received rituximab and bendamustine for follicular lymphoma and achieved complete response two years prior to developing moderate anaemia (94 g/L) and thrombocytopenia (44×10 9 /L). Blood film showed circulating nucleated red cells and proerythroblasts with dysplasia (A, B). Diagnostic bone marrow aspirate was a dry tap. Trephine imprints showed 42% nucleated red cells with significant dysplasia such as binucleation, nuclear irregularity and cytoplasmic vacuoles (C). Immature erythroblasts were increased but comprised ＜ 30% of nucleated cells. There was minimal maturation beyond the proerythroblast phase. Trephine core was hypercellular with abnormal megakaryocytes and erythroblasts (D). The latter showed weak membranous staining with anti-CD117 (E) and variable patterns of glycophorin A (F). Intra-sinusoidal infiltration of proerythroblasts were highlighted. There was no evidence for increased myeloblasts, granulocytic