Clues from the Blood Film

Clues from the Blood Film

Finding	Interpretation/causes
Red cells
Red cell aggregration	Rouleaux, seen in: High polyclonal immunoglobulin (e.g. acute phase response) Monoclonal immunoglobulin (paraprotein, e.g. myeloma) High fibrinogen Agglutination, reflecting the presence of cold agglutinin, seen in: Mycoplasma infection Infectious mononucleosis Lymphoproliferative disorder Idiopathic
Fragmented red cells (schistocytes)	Microangiopathic haemolytic anaemia, seen in: Disseminated intravascular coagulation Thrombotic thrombocytopenic purpura/haemolytic uraemic syndrome Systemic infection Metastatic cancer Severe preeclampsia/eclampsia Severe hypertension with fibrinoid necrosis Autoimmune/vasculitic disorders (e.g. systemic lupus erythematosus, systemic sclerosis, antiphospholipid syndrome) Haematopoietic stem-cell or organ transplantation Prosthetic heart valve Severe burns
‘Bite cells’ (keratocytes)	Acute haemolysis induced by oxidant damage (e.g. in glucose-6-phosphate dehydrogenase deficiency)
Target cells	Iron deficiency Thalassaemia Liver disease Post-splenectomy
Nucleated red cells	Marrow replacement, due to: Carcinoma (most commonly of breast or prostate origin) Myelofibrosis Myeloma Tuberculosis
Red cell inclusions – Howell-Jolly bodies	Post-splenectomy
White cells
Blast cells	Leukaemias Lymphomas Marrow replacement (see above)
Platelets
Platelet clumps	EDTA-induced platelet clumping may cause spurious thrombocytopenia
Other findings
Abnormal cells	Lymphoma cells Plasma cells (myeloma)
Parasites	Malaria

Adapted from: Bain BJ (2005) Diagnosis from the blood smear. N Engl J Med 353, 498–507; Tefferi A, Hanson CA, Inwards DJ, et al. (2005) How to interpret and pursue an abnormal complete blood cell count in adults. Mayo Clinic Proc 80, 923–936.

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Table 100.2