In Western countries, chronic lymphocytic leukaemia (CLL) is by far the most common lymphoid malignancy [1-3]. It is a disease predominantly of the middle aged and elderly with the incidence being considerably higher in men than in women. In some instances a familial tendency to develop CLL can be demonstrated  and family members may have monoclonal B-cell lymphocytosis . Diagnosis requires the presence of significant lymphocytosis, often arbitrarily defined as a lymphocyte count exceeding either 5 or 10 × 109/l. The lymphocytes are clonal B cells with a very characteristic immunophenotype. There is often a long asymptomatic phase in CLL so that incidental diagnosis is common and many patients subsequently die with the disease rather than of the disease.
Small lymphocytic lymphoma is a lymphoma in which the neoplastic cells have the same cytological and immunophenotypic features as those of chronic lymphocytic leukaemia but without there being significant lymphocytosis at diagnosis. In some patients with small lymphocytic lymphoma a leukaemic phase subsequently occurs.
In patients in whom the diagnosis of CLL is incidental there may be no symptoms and no abnormal physical findings. In other patients with more advanced disease, presentation may be with lymphadenopathy, with or without splenomegaly or hepatomegaly, or with infection, bruising or symptoms of anaemia (Figures 3.1 and 3.2). Infections that are particularly prevalent among these patients are herpes zoster (Figure 3.3) and pneumococcal pneumonia. Autoimmune complications, specifically autoimmune haemolytic anaemia, autoimmune thrombocytopenic purpura and pure red cell aplasia, may be present at diagnosis and are common during the course of the disease. Small lymphocytic lymphoma usually presents with lymphadenopathy, with or without splenomegaly or hepatomegaly.
Clinical photograph showing cervical lymphadenopathy in a patient with CLL.
Clinical photograph showing skin infiltration in a patient with CLL.
Clinical photograph showing herpes zoster in a patient with CLL.
CLL can undergo transformation to a large cell lymphoma. In addition, diffuse large B-cell lymphoma can arise in a B cell that does not belong to the neoplastic CLL population, this being found in around half of cases . Epstein-Barr virus (EBV) is an aetiological factor in some cases of large cell lymphoma arising from a cell of the CLL clone and also in some cases arising in an unrelated non-clonal B cell; this occurrence reflects the immune deficiency of CLL. All these types of transformation are encompassed by the term 'Richter's syndrome'. Richter's syndrome can arise in a lymph node or at an extra-nodal site including bone marrow. It should ...