RBC Inclusions: Heinz Bodies and Howell-Jolly Bodies
The college loves Heinz bodies and Howell-Jolly bodies. RBC inclusion bodies have appeared in several SAQs, and are usually associated with a question on post-splenectomy vaccination. Most often, the question is worth 10-20% of a multi-part question, and represents easy marks for the person who can remember a handful of differentials. Thus far, the college has not ask anything about siderocytes or basophilic stippling.
Representative SAQs include the following:
- Question 7.2 from the first paper of 2016 (Post-splenectomy Howell-Jolly bodies)
- Question 12.2 from the second paper of 2012 (Post-splenectomy Howell-Jolly bodies)
- Question 24.3 from the second paper of 2010 (Heinz bodies in G6PD)
- Question 18 from the second paper of 2007 (Post-splenectomy film)
Howell-Jolly bodies are bits of lefteover DNA in the erythrocytes. Normally, the spleen would view these as defective, and they would be removed. They are typically seen in patients who have had a splenectomy.
Other associations include the following conditions:
- Pernicious anaemia
- Macrocytosis of any cause
- Corticosteroid use
Heinz bodies, also known as Heinz-Ehrlich bodies are essentially little lumps of denatured haemoglobin within the red cells. They typically indicate some sort of oxidative stress. This sort of abnormality is usually seen in disorders of red cell metabolism and haemoglobinopathies. Additonally, a normal individual probably has a few RBCs with Heinz bodies, but they are rapidly cleaned up by splenic macrophages (and thus after splenectomy they begin to accumulate).
Increased oxidative stress due to toxins
- Toxic solvents, eg. aniline, benzene, naphthalene
- Chronic liver disease
- Certain congenital "Heinz body anaemias"
- Methylene blue methaemoglobinaemia
Deranged RBC metabolism
- Dapsone toxicity
- Glucose-6-phosphate dehydrogenase deficiency
- Trimethoprim-sulfamethoxazole (Bactrim)
Decreased clearance of defective RBCs
- Post splenectomy
Miscellaneous RBC inclusion bodies:
Blister cells: blebs on the surface of RBCs, suggestive of oxidative damage; seen with G6PD deficiency as well as in various oxidative stress states, eg. dapsone or primaquine toxicity. Within the same film one might expect a few Heinz bodies.
Pappenheimer bodies: hemosiderin-containing granules seen in sideroblastic anaemia
Basophilic stippling: altered ribosomes in the cytoplasm; seen with lead poisoning