The smear findings Step 1 expects you to name on sight — each drawn as a schematic, with its mechanism and its diseases.
FOCUS ON
Link shape to mechanism and the disease follows. Lost membrane gives a sphere. Relative excess membrane gives a target. Shear gives fragments. A squeezed marrow gives teardrops. Spleen-removed inclusions give bite cells. No spleen leaves inclusions behind (Howell-Jolly). Drawings are schematic, not photographs.
SHAPE
NAME
WHY IT FORMS
THINK OF
Spherocyte
no central pallor
Membrane lost (inherited defect or antibody nibbling) → smallest surface for its volume.
Hereditary spherocytosis, warm AIHA, burns
Schistocyte
helmet cell, fragments
RBCs sheared by fibrin strands or turbulent flow.
TTP, HUS, DIC, HELLP, mechanical valves
Target cell
codocyte
Too much membrane relative to hemoglobin (↓ Hb or ↑ membrane cholesterol).
Thalassemia, HbC, liver disease, asplenia
Sickle cell
drepanocyte
Deoxygenated HbS polymerizes into rigid rods.
Sickle cell disease
Teardrop cell
dacrocyte
Cells squeezed out of a fibrotic or infiltrated marrow.
Myelofibrosis, myelophthisis
Bite cell
degmacyte
Splenic macrophages remove Heinz bodies, taking a "bite."
G6PD deficiency
Heinz bodies
supravital stain
Oxidized, denatured hemoglobin clumps on the membrane.
G6PD deficiency, unstable hemoglobins
Echinocyte
burr cell — even spikes
Membrane changes from low ATP, uremia, or drying artifact.
Pyruvate kinase deficiency, uremia, artifact
Acanthocyte
spur cell — irregular spikes
Abnormal membrane lipids.
Liver disease, abetalipoproteinemia
Elliptocyte
ovalocyte
Spectrin defect in horizontal membrane links.
Hereditary elliptocytosis; some in iron deficiency
Hypersegmented neutrophil
≥ 5 lobes · with macro-ovalocytes
Nuclear maturation lags in impaired DNA synthesis.
B12 or folate deficiency, methotrexate
Basophilic stippling
ribosomal RNA dots
RNA not broken down (lead blocks rRNA degradation).
Lead poisoning, thalassemia, sideroblastic anemia
Howell-Jolly body
nuclear remnant
Normally pitted out by the spleen; stays when the spleen is absent or not working.
Splenectomy, sickle cell autosplenectomy
Ringed sideroblast
marrow, Prussian blue
Iron trapped in mitochondria circling the nucleus.
Sideroblastic anemia (alcohol, lead, B6, MDS)
Rouleaux
coin stacks
High plasma protein (Ig, fibrinogen) cancels the cells' negative charge.
COMMON CONFUSIONEchinocytes have many short, even spikes; acanthocytes have a few irregular, long spikes. Liver disease can show either.
THE TRAPHowell-Jolly bodies in an adult with sickle cell disease mean autosplenectomy. Treat it as functional asplenia: vaccines and fever precautions.
YOUR APPROACHName the shape → recall the mechanism → choose the disease that fits the rest of the stem.