Viral - a modest and temporary (< 2 months) rise in lymphocytes
If the patient is unwell, request a blood film and consider testing for EBV, CMV, HIV.
Nb. The EBV screen (Monospot or Paul Bunnell) gives both false positive and false negative results and requesting serology for IgG and IgM antibody is preferable and specific.
Some bacterial (eg pertussis) and protozoal (eg toxoplasmosis) infections also cause a lymphocytosis.
Smoking is a common cause of low level and persistent lymphocytosis.
Less common causes of lymphocytosis include auto-immune disease, medication and stress (extreme exercise, cardiac or trauma)
Lymphocytes may rise most commonly with chronic lymphocytic leukaemia (CLL) and similar low grade lymphoproliferative disorders (LPD).
A variety of lymphomas may also ‘spill’ into the peripheral blood.
Acute lymphoblastic leukaemia (ALL) is rare and the patient would likely be unwell with other blood abnormalities. The blood film would show blast cells. Refer ALL immediately via medical admissions for inpatient care.
Asymptomatic CLL does not benefit from early treatment. Lymphocytosis without symptoms can reasonably be monitored in the community with a second FBC after 2 months and then annually.
When to refer CLL:
- If the lymphocyte count is rising rapidly (> 10 x 109 / l and doubling within a 3 month period)
- the patient is systemically unwell (involuntary weight loss, night sweats)
- significant and persistent lymphadenopathy
- other components of the blood count are abnormal (anaemia, thrombocytopenia)
Examine for lymphadenopathy and splenomegaly
Seek reactive causes
Refer to routine Haematology if lymphocytosis &:
Significant and persistent (> 2 weeks) lymphadenopathy in the absence of a secondary cause
Anaemia or thrombocytopenia
Lymphocytes > 10 x 109 / l and double within a 3 month period
(2ww may be appropriate if significantly unwell)
Useful patient resources:
Dr Richard Noble, Consultant Haematologist, RCHT
Dr Bridgitte Wesson, GP & Kernow RMS Haematology guideline lead
Review date: 13/07/2020
Next Review due 13/07/2021