A 33-year-old male who is 4 weeks after gunshot wounds to his chest and abdomen has the following report on his blood film:
- Moderate anisocytosis.
- Moderate polychromasia.
- Occasional Howell-Jolly bodies.
- Increased rouleaux formation.
a) What is meant by the term 'polychromasia' and what is its significance? (10% marks)
b) What are Howell-Jolly bodies, and what is their significance? (15% marks)
c) List two other features you might expect to see on the blood picture of a patient with Howell-Jolly bodies. (10% marks)
- Variation in RBC colour due to immature forms. Consistent with bone marrow stimulation.
- Residual nuclear remnants in red cells that have not been removed the spleen.
- Usually indicates hypofunctional or absent spleen – presumably secondary to the trauma. (Occasionally seen in haemolysis or megaloblastic anaemia)
- Any two of:
- Heinz bodies
- target cells
- Pappenheimer bodies
Polychromasia is another one of those morphological RBC abnormalities which the college love so much. It is an abnormally large raneg of colour variation among the (usually, red) erythrotcytes. It indicates the presence of an increased number of morphologically immature RBCs which have RNA inside them (and which therefore stain grey-blue with the giemsa stain). The stolen image below has helpful arrows pointing at them.
These cells are significant, because they represent either increased bone marrow stress or a failure of normal regulatory mechanisms responsible for "quality control" of erythrocytes.
Possible causes of polychromasia include:
- Response to red cell loss by normal marrow:
- Recovery of normal marrow function
- Iron infusion
- Vitamin B12 replacement
- Erythropoietin injection
- Recovery following chemotherapy
- Failure of bone marrow to sustain normal function
- Malignant marrow infiltration
- Failure of RBC quality control
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
In this patient, splenectomy is the most likely common unifying diagnosis. There is a history of trauma to a vaguely spleeny area, and he has rouleaux (which suggest he may have post-splenectomy thrombocytosis). This question therefore resembles Question 18 from the second paper of 2007, which asked for the features of a post-splenectomy blood film.
The typical post-splenectomy blood film abnormalities are as follows:
- Howel-Jolly bodies
- Target cells
- Pappenheimer bodies
- Platelet aggregates
Davidson, E. "The significance of blue polychromasia." Journal of clinical pathology 12.4 (1959): 322.
Ponder, Eric. "On sedimentation and rouleaux formation-I." Experimental Physiology 15.3 (1925): 235-252.
Walker, H. Kenneth, et al. "Peripheral blood smear." (1990). in Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition.