<p>'Rouleaux formation' can often appear in normal blood samples, when parts of the blood film are too thick, or too much blood is used to prepare the blood film.</p>

<p>'Rouleaux formation' or clumping of the red blood cells is often found in cases where cold agglutinins are present. (Cold agglutinins cause haemolysis. Erythropoiesis is raised compensatorily, which can be recognised by the appearance of polychromasia.)</p>

<p>'Rouleaux formation' is not specific for multiple myeloma or lymphoma. Also polyclonal immunoglobulins can cause 'rouleaux formation' (-&gt;) in peripheral blood (May-Grünwald-Giemsa stain), as shown in this patient with chronic polyarthritis.</p>

<p>In peripheral blood of a patient with multiple myeloma (May-Grünwald-Giemsa stain) no plasma cells are detectable, because in multiple myeloma these are only rarely found in the periphery. The monoclonal immunoglobulin causes an increased erythrocyte sedimentation rate (ESR) and 'rouleaux formation' (-&gt;) of red blood cells.</p>

<p>Abnormal platelets of a patient suffering from myelodysplastic syndrome (MDS). (The upper one is reminiscent of a 'paramecium', the lower of a 'flagellate'.) In this type of disease, very strange shapes may appear in all cell lines.</p>

<p>This bone marrow histology (Giemsa stain) of a patient with ET shows abundant and atypical megakaryocytes (-&gt;) (too large, atypically segmented, ring-shaped nucleus).</p>

<p>Acanthocytes with protrusions of differing lengths and widths as seen in acute hepatic failure. (This may be caused by modifications of the membrane-bound proteins.)</p>

<p>Acanthocytes in the presence of A-β-lipoproteinaemia. In cases of dysfunctional lipid metabolism, the composition of red blood cell membranes is disturbed.</p>

<p>Accumulation of platelets on granulocytes in the presence of EDTA (= platelet satellitosis). In vitro, this effect can lead to pseudo-thrombocytopenia.</p>