SN7 SHORT NOTE 5M

Describe the abnormal red cell shapes and inclusions seen on a peripheral smear with their significance.

Pathology · 2nd Professional — Para-Clinical

Abnormalities of Red Cell Shape

Cell	Appearance	Associations
Spherocyte	Small, round, dense, NO central pallor	Hereditary spherocytosis; warm autoimmune haemolytic anaemia
Target cell (codocyte)	Central dense area within the pallor — a "bull’s eye"	Thalassaemia, iron deficiency, liver disease, post-splenectomy, HbC
Sickle cell (drepanocyte)	Crescent-shaped, pointed ends	Sickle cell disease
Schistocyte (fragment, helmet cell)	Irregular fragments	Microangiopathic haemolysis — DIC, TTP, HUS; prosthetic valves
Tear-drop cell (dacrocyte)	Pear-shaped	Myelofibrosis; marrow infiltration; thalassaemia
Pencil (elongated) cell	Thin and elongated	Iron deficiency
Elliptocyte	Oval	Hereditary elliptocytosis
Bite cell and blister cell	A "bite" taken from the margin	G6PD deficiency
Acanthocyte (spur cell)	Irregular spiky projections	Liver disease, abetalipoproteinaemia
Echinocyte (burr cell)	Regular short spicules	Uraemia; artefact
Rouleaux	Stacked like coins	Myeloma; raised fibrinogen; high ESR

Red Cell Inclusions

Inclusion	Composition	Stain	Associations
HOWELL–JOLLY body	Nuclear (DNA) remnant — single, round, dense	Routine (Romanowsky)	Hyposplenism or splenectomy; megaloblastic anaemia
Basophilic stippling	Aggregated ribosomal RNA — fine blue granules	Routine	Lead poisoning, thalassaemia, sideroblastic anaemia
HEINZ body	Denatured, precipitated haemoglobin	Supravital only (methyl violet) — not seen on a routine film	G6PD deficiency; unstable haemoglobins
Pappenheimer body	Iron-containing granules	Routine and Prussian blue	Sideroblastic anaemia; post-splenectomy
Cabot ring	Remnant of the mitotic spindle	Routine	Megaloblastic anaemia; lead poisoning
Ring sideroblast	Iron-laden mitochondria encircling the nucleus of an erythroblast	Prussian blue on marrow	Sideroblastic anaemia; myelodysplasia
Malarial parasite	Trophozoites, schizonts, gametocytes	Routine; Leishman or Giemsa	Malaria

CLINICAL PEARL

Heinz bodies are invisible on an ordinary film, and that is the point of the question. They must be sought with a supravital stain. Their removal by splenic macrophages leaves the "bite" cells that are visible on the routine film — so in practice one looks for bite cells and infers the Heinz bodies.

Useful Combinations

Howell–Jolly bodies + target cells + Pappenheimer bodies = hyposplenism; look for it in coeliac disease and sickle cell disease as well as after splenectomy
Basophilic stippling + microcytic anaemia + abdominal pain = lead poisoning
Schistocytes + thrombocytopenia = a microangiopathic process, demanding urgent attention
Hypersegmented neutrophils + macro-ovalocytes = megaloblastic anaemia
Rouleaux + a high ESR + bone pain = myeloma

Applied Aspects

The peripheral smear is the cheapest and most informative haematological test, and in Indian practice it detects malaria, leukaemia and nutritional anaemia at almost no cost
Automated counters flag abnormalities but cannot replace the film — they will not recognise a malarial parasite or a schistocyte
A thick and thin film for malaria should be examined in any febrile patient with anaemia in an endemic area
Correct staining and a well-made film matter; most reported "abnormalities" in poorly made films are artefacts, particularly echinocytes
Always examine the tail of the film for rouleaux, agglutination and large abnormal cells, which collect there

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