The patient’s folate level at the time of biopsy was 1.4 ng/mL (reference range: 7.0-31.0 ng/mL). Peripheral blood counts normalized after folate repletion. Myeloid precursors show megaloblastic changes, including giantism of bands and metamyelocytes (A, 100X). The erythroid precursors show nuclear-cytoplasmic asynchrony, as well as nuclear budding and late mitoses (A, B, 100X; C, 50X). The megakaryocytes also show nuclear abnormalities (D, 50X). The marrow hypercellularity is seen on hematoxylin-and-eosin-stained section of the core biopsy (E, 20X). Lacking from this case is the marked erythroid predominance and erythroid left-shift that can be seen in some cases of vitamin B12 or folate deficiency.